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COLEGIO VILLA RICA
JR HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:________________ Group:______________
LAB PRACTICE # 12
Earths Magnetic Field
Previous investigation:
1. What are three properties of magnets? ______________________________________________________________________________________________________________________________________________________________________________________________________
2. What are two ways a magnet can be made? ____________________________________________________________________________________________________________________________________
Experiment 1: Can You Use a Needle to Make a Compass?
Skills Focus: Observing
Materials: large needle, strong bar magnet, dish, water, dishwashing soap, cork or foam ball
Procedure:
1. Magnetize a large needle by rubbing it several times in the same direction with one end of a strong bar magnet. Push the needle through a ball of foam or tape it to a small piece of cork.
2.
3. Place a drop of dishwashing soap in a bowl of water. Then float the foam or cork in the water. Adjust the needle until it floats horizontally.
4. Allow the needle to stop moving. Note the direction it points.
5. Use a local map to determine the direction in which it points.
Tips
Handle the needle carefully. Rub the needle in only one direction. Magnetized objects in the room may attract the needle. Use a compass to verify that the needle points north.
Questions:
1. In what direction did the needle point? __________________________________________________________________
2. If you repeat the activity, will it still point in the same direction? __________________________________________________________________
3. What does this tell you about Earth? __________________________________________________________________
Experiment 2: Spinning in Circles
Skills Focus: Drawing conclusions
Materials: bar magnet, sheet of paper, compass
Procedure:
Which way will a compass point?
1. Place a bar magnet in the center of a sheet of paper.
2. Place a compass about 2cm beyond the north pole of the magnet. Draw a small arrow showing the direction of the compass needle.
3. Repeat Step2, placing the compass at 20 to 30 different positions around the magnet.
4. Remove the magnet and observe the pattern of arrows you drew.
Tips
Use a bar magnet that is much larger than the compass to give the most accurate results.
Drawing Conclusions:
1. What does your pattern of arrows represent? ________________________________________________________________________
2. Do compasses respond only to Earths magnetic field? _______________________________________________________________________
COLEGIO VILLA RICA
JR HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:___________________
LAB PRACTICE # 13
DENSITY OF SOLIDS
PREVIOUS INVESTIGATION
1. What formula do you use to obtain the volume of a cube?
2. Define density? _______________________________________________________________________________
3. What formula is used to determine the density of a substance?
4. Which unit does the S.I use to measure density? ______________________________________
5. What temperature is used to measure the density of solid substances? ____________________
INTRODUCTION
Mass is a fundamental magnitude defined as the measurement of the amount of matter in a body. Its also considered as the measurement of the inertia, which is the tendency of a body to resist changes in movement.
Volume is a derived magnitude, which is obtained by multiplying length x length x length. It is defined as the measurement of a regions extension in space or the extension occupied by a body.
When a body has a regular geometrical shape the volume is obtained using a formula, but when its an irregular solid body, liquid or gas, the volume is obtained using other methods such as displacement of water.
Density is a magnitude measuring the mass of a substance contained in a unit of volume. The densities of substances are already established, as seen in the density chart on the next page.
Density at a 20 0C temperature:
Substance
g/cm3
kg/m3
wood
0.4 - 0.6
400 600
cement
0.83 1.95
830 1950
marble
2.5 2.8
2 500 2 800
silver
10.50
10 500
gold
19.30
19 300
mercury
13.6
13 600
OBJECTIVE:
Determine the mass, volume and density of regular and irregular shaped solid bodies.
MATERIAL:
balance
30 cm ruler
100 ml graduated cylinder
Wooden cube
Glass marble
Iron screw
SUBSTANCES:
50 ml of water
PROCEDURE:
1.- Using a balance, determine the mass of the wooden cube.
2.- Using the ruler, measure the sides of the cube and determine its volume.
3.- Write down your observations in the chart and determine the density.
Mass (g)
Volume ( cm3)
Density ( g/cm3 )
4.- Determine the volume of the marble, the screw and the coin using the balance.
5.- Determine the volume of these solid bodies using the displacement of water method.
6.- Pour 50 ml of water in the graduated cylinder, this is the initial volume.
7.- Place the marble in the cylinder and write down what the final volume is.
8.- Subtract the initial volume from the final volume in order to obtain the marbles volume.
9.- Repeat this procedure for the screw and coin.
10.- After youve registered all the data in the chart, calculate the density.
Object
Bodys mass (g)
Waters final volume( cm3)
Bodys volume (cm3)
Density (g/cm3)
Glass marble
Iron screw
QUESTIONS.
Compare the results you obtained with the following density chart and see if they match.
Material
Density
Lab result
Do they match?
wood
0.4 - 0.7 g/cm3
glass
2.6 g/cm3
iron
7.8 g/cm3
1. Do all the results match? ____________________________________________________
2. If one doesnt, why do you think this happened? ______________________________________
3. Which of the objects you used floats in the water? _____________________________________
4. Explain why: _________________________________________________________________
5. Why does ice float in water? __________________________________________________
6. What type of unit is density measured with? ______________________________________
7. What magnitudes/ units does density use? __________________________________________
COLEGIO VILLA RICA
JUNIOR HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:_____________ Group:_______________
LAB PRACTICE # 14
Build Your Own Thermometer
Previous investigation:
1. How does a thermometer work? _________________________________________________________________
2. Are all thermometers the same? __________________________________________________________________
3. How are extreme temperatures (high and low ones) measured? __________________________________________________________________
General information: Thermometers, like the ones we will be building in this lab practice, were built not so long ago by people like Daniel Fahrenheit, Anders Celsius and many others. They all took as a reference different phenomena and created their own scales, and in order to understand the equivalencies between them, calculations must be made based on formulae. Nowadays, people dont use such conversions to standardize measurements. The International System has determined that the Kelvin scale should be employed without the word degrees.
Design Skills: evaluating the design, measuring, making models
Materials
bowl of hot water
bowl of ice water
water of unknown temperature
tap water
500-mL beaker
food coloring
plastic dropper
metric ruler
cooking oil
clear glass bottle, 2025 cm tall
clear plastic straw, 1820 cm tall
modeling clay
fine-point marker
Procedure:
1. You can use simple materials to build a model of an alcohol thermometer. First, mix food coloring into a beaker of tap water. Then fill a glass bottle with the colored water.
2. Place a straw in the bottle. Use modeling clay to position the straw so that it extends at least 10 cm above the bottle mouth. Do not let the straw touch the bottom. The clay should completely seal off the bottle mouth. Make sure there is no air in the bottle.
3. Using a dropper, add colored water into the straw to a level 5 cm above the bottle. Place a drop of cooking oil in the straw to prevent evaporation.
4. Place your thermometer into a bowl of hot water. When the colored water reaches its highest level, place a mark on the straw.
5. Place your thermometer in the bowl of ice water. Place a mark on the straw when the water reaches its lowest level.
6. Create a scale for your model thermometer. Divide the distance between the two marks into 5-mm intervals. Starting with the lowest point, label the intervals on the straw 0, 1, 2, 3, and so on.
7. Measure the temperature of two unknown samples with your thermometer. Record both temperatures.
Analyze and Conclude
1. Evaluating the Design Do you think your model accurately represents an alcohol thermometer? How is it like a real thermometer? How is it different?
2. Inferring How can you use the concepts of matter and the kinetic energy of particles to explain the way your model works?
3. Measuring Approximately what Celsius temperatures do you think your model measures? Explain your estimate. (Hint: Referto Figure 3 in your textbook.)
4. Making Models Examine the structure and materials used in your model. Propose a change that would improve the model. Explain your choice.
COLEGIO VILLA RICA
JR HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:___________
LAB PRACTICE # 15
Heat Transfer
Previous investigation: Why are the containers used to cook foods usually made of metals? Why does the temperature on a clear night descend more quickly than when there are clouds? In winter, where should the heater be placed in the room, near the floor or near the ceiling?
Explain.
Objective: To appreciate the heat transfer by convection and the establishment of the heat balance.
General information: In fluids (liquids and gases), heat is transmitted mainly by convection, which is a transmission by means of currents. For example, the air in contact with a hot surface increases its temperature and rises. The space that it leaves is occupied by cold air, which increases its temperature and rises. When it rises, the air cools off, and consequently it descends. This process repeats and gives rise to that which is known as convection currents. The air rises because, while warming up, it expands, that is to say, increases its volume, so its density diminishes and thus, it becomes lighter
Experiment 1
Material:
An Erlenmeyer flask of 125 ml
1 universal ring stand
1 wire gauze
1 Bunsen burner
1 Metallic sphere
Beaker of 1000 ml
1 thermometer
1 tong
1 metal ring
30 cm of thread
Sawdust
Procedure:
1. - Fill three quarters parts of the flask with water and heat it for 10 minutes. Place into its interior the sawdust and add a few drops of ink. Add some cold water to the beaker, to a level of about 2 cm from the edge. Measure the temperature of the water that is in the flask and in the beaker. Register the values.
2. - Take the flask with the tongs and place it inside the beaker. Observe the rising currents of the hot water and later the descending when it cools.
3. - After 5 min. measure the temperature of the water in the two containers and register the values.
Temperature of the flask with hot water
Temperature of the cold water in the beaker
Temperature of both containers after 5 min.
Experiment 2Objective: Observing the enlargement of the solids with the metal ring .Procedure: 1. -Observe if the sphere passes through the ring. 2. Heat the ring. 3. Observe again if the metal sphere passes through the ring.
Questions:
1. How does heat affect solids?
2. Why does hot air rise and cold air descend?
3. When was thermal equilibrium established in the first experiment?
4. What happens after heating the sphere?
5. What is expansion?
6. How is expansion produced?
COLEGIO VILLA RICA
JR HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 16
Air and atmospheric pressure
Previous investigation: What is the device called that measures atmospheric pressure?
Draw Torricellis Evangelist experiment.
Objective: To observe the volume of fluids and to verify that air occupies a certain space. To observe the effects of atmospheric pressure. To verify if the pressure of a liquid depends on the height of the column
General information: The Earth is surrounded by a layer of atmosphere called air, various hundreds of kilometers in thickness. This layer of air, like any substance that is found on the surface of the Earth, has weight and exercises a pressure over all bodies. The greater the altitude in a place, the less dense and thinner the thickness of the atmosphere there and, therefore, the atmospheric pressure will be lower.
Experiment 1
Material:
1 funnel
clay or adhesive tape
1 soft drink bottle.
Procedure:
-Place the funnel on the mouth of the bottle.
-With the clay or the adhesive tape seal perfectly the union of the funnel and the bottle, taking care so that no opening remains.
-Fill the funnel with water. Once you have joined the two pieces together, you will see that the funnel itself fills but the water does not pass to the bottle.
What happens? _____________________________________________________________________
Why wont water from the funnel drain into the bottle? _________________________________
Experiment 2
Material:
A glass
A handkerchief or wipee
A bucket filled with water
Procedure:
- Place the handkerchief in the interior of the glass and leave it touching the bottom.
- With care and trying to keep the glass vertical introduce it completely in the bucket with water and in the same position withdraw it from the bucket. Observes the state of the handkerchief
Was the handkerchief wet? _______________
What caused this? _______________________________________________________
Experiment 3
Material:
A glass
A piece of cardboard bigger than the diameter of the glass
Procedure:
-Fill the glass with water until it spills
-Place the cardboard on the top edge of the glass. Now turn it upside down.
-Turn the glass sideways.
*What happened? ________________________________________________________________
*Why did this occur? _____________________________________________________________
Experiment 4
Material:
A recipient with water
A plastic bottle with a bottle cap
Procedure:
- Heat a certain quantity of water in a container.
- Submerge an empty plastic bottle without the bottle cap in the water and leave it there for a while (3 minutes)
- Replace the bottle cap completely, remove it from the hot water, and place it under cold water.
What happened to the bottle when it came into contact with cold water? _________________________________
Why? _________________________________________________________________________________
What happens to the air inside the bottle when it becomes hot? ____________________________________
Experiment 5
Material:
A can or bottle with holes at different heights.
Procedure:
-Fill the can with water up to the tip.
-Observe as the water flows through all the different holes.
-Now cover the upper part of the can with the palm of your hand.
Are the spurts equal in length? ______________________________________________________
Explain the reason why the hole that is farther down has greater length.
_______________________________________________________________________________
What happens with the atmospheric pressure when you cover the can?
_______________________________________________________________________________
What happens when you uncover it?
_______________________________________________________________________________
Experiment 6
Material:
2 cups joined together
Colored water
Procedure:
What do you expect will happen to a liquid poured into this device?
_______________________________________________________________________________
What happened to the height of the liquid when equilibrium was established?
_______________________________________________________________________________
On what does the pressure in the columns of liquid depend? _______________________________________________________________________________
Mention 2 practical applications for this mechanism:
______________________________________________________________________________________________________________________________________________________________
Experiment 7: Can You Blow Up a Balloon in a Bottle?Materials: 2-L plastic bottle, small balloon, strawProcedure:
1. Insert a balloon into the neck of an empty bottle. Try to blow up the balloon.
2. Now insert a straw into the bottle, next to the balloon. Keep one end of the straw sticking out of the bottle. Try again to blow up the balloon.
Developing Hypotheses:
1. Did using the straw make a difference? _________
2. If it did, develop a hypothesis to explain why. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
COLEGIO VILLA RICA
HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:___________________
LAB PRACTICE # 17
Density and Buoyancy
Previous Investigation:
1. Substances take up different amounts of space according to their differing densities. Make a list of the different states in which you can find water from least dense to most dense. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
2. How does water behave differently from most substances? ______________________________________________________________________________________________________________________________________________________________________________________________________
3. What other substances can you find that do not follow the general rules of density? ______________________________________________________________________________________________________________________________________________________________________________________________________
Introduction:
Density is a measure of a substance's mass relative to the amount of space it takes up. Dense substances, like iron and other metals, are massive -- they weigh a lot but take up very little space. Gases, in contrast, take up a great deal of space and weigh very little.
For many substances, including most solids, density varies only slightly with changes in temperature. The density of gases, and to a lesser extent that of liquids, changes as ambient temperatures rise and fall. The molecules of these substances generally become more active and more spread out -- less dense -- as temperatures rise. Conversely, they become more tightly packed as temperatures decrease. Water follows these general rules, but with two exceptions that are important to life on Earth. First, water is less dense as a solid than as a liquid. This is because of the way water molecules arrange themselves when they form ice crystals. The crystalline structure of ice holds molecules at greater distances from one another than when they are in a liquid form. This phenomenon explains why ice is less dense and floats on water. If this weren't the case, lakes, ponds, and oceans, even in temperate parts of the world, would likely freeze permanently.
Second, water is most dense at about 4 degrees C. As it warms up from 0 degrees and begins to near the 4-degree mark, it becomes increasingly dense. Then, like most other substances, it becomes less and less dense as temperatures continue to rise. In spring and fall, temperature changes cause the densest water at the surface of a lake or pond to fall to the bottom, where it replaces warmer or cooler water. This causes nutrients that have settled at the bottom and oxygen concentrated near the surface to become more evenly distributed throughout a lake or pond, thus making them more available to the aquatic organisms that need them.
Experiment 1: Mixing Hot and Cold Water
Objective: To observe the behavior of water at different densities.
Procedure:
1. Take a bottle and fill it with cold water.
2. Take a second bottle and fill it with very warm water and food coloring.
3. Cover the mouth of the bottle containing cold water with an index card.
4. Slowly, flip the bottle upside down, holding the card in place over the bottle.
5. Set it on top of the bottle with the colored warm water.
6. Carefully remove the index card and make sure the bottles are aligned.
7. Observe results.
8. Next, take two bottles of cold water, one with food coloring and one without color.
9. Repeat steps #2-7.
10. Observe results.
Discussion Questions
1. Why did the warm water float on top of the cold water? ____________________________________________________________________________
2. What would happen if you reversed the bottles, placing the one with warm water on top? ____________________________________________________________________________
3. What do you think would happen after an hour? After four hours? How would the temperatures compare then? ____________________________________________________________________________ ____________________________________________________________________________
4. Why did you repeat the experiment using two bottles of cold water instead of one cold and one warm bottle? ____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
Experiment 2: Layering Liquids
Materials
corn syrup, food coloring, glycerin, rubbing alcohol, tall, clear container, vegetable oil, water
Objective
To observe objects and their densities in relation to other objects.
Procedure:
1. Pour a layer of corn syrup into the tall container.
2. Then add a layer of glycerin.
3. When the glycerin has settled, add liquids in this ordercolored water, vegetable oil, and colored rubbing alcohol.
4. Pour gently to avoid mixing.
Questions:
1. Why do the different liquids float on top of each other? ____________________________________________________________________________________________________________________________________
2. Which liquids used in this demonstration have a density greater than water? ____________________________________________________________________________________________________________________________________
Experiment 3: Density Demonstration: Coke vs. Diet Coke
Objectives:
to list similarities of given objects
to brainstorm and find a solution as to why Diet Coke floats and Coke sinks
to define the term density
to see how much sugar we consume drinking one can of soda
Materials:
12 ounce coke can
12 ounce diet coke can
water
fish tank
sugar
NutraSweet
triple beam balance
Procedure:
1. Pass the cans of coke around the room. Look at each can and make careful observations about what you see.
2. Name as many similarities as you can about the 2 cans of coke. Make a list in your lab manual.
3. List the differences about the 2 cans. Add to your list.
4. Place the regular coke into a small tank of water.
5. Place the diet coke into the water.
6. Record your observations in your lab manual.
7. Using a triple beam balance, weigh out 39g of sugar in one beaker and 188mg. NutraSweet (aspartame) in another beaker.
8. Weigh the Coke and Diet Coke to determine mass of each can.
9. Using water displacement, find the volume of each can. Use the formula D=M/V and see if you can determine their densities.
Mass of can (g)
Volume of can (cm3)
Density of can D=M/V (g/cm3)
Coke
Diet Coke
Note: The Density of water is 1g/cm3
Questions:
1. What explanations can you come with as to why one can floated when the other one did not? Give at least two possibilities. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
2. Is Diet Coke's density less than 1? _______________________________________
3. Is regular Coke's density greater than 1?___________________________________
COLEGIO VILLA RICA
HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:___________________
LAB PRACTICE # 18
PASCAL PRINCIPLE and ARCHIMEDES PRINCIPAL
previous investigation:
Research Pascals principle.
___________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
How does a hydraulic system function?
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
What are some uses of hydraulic systems? ____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
introduction:
Imagine you are living an adventure movie. You are a team of secret agents investigating enemy headquarters. You are excellent divers and as a secret agent you must be ready for anything. You have tanks with unlimited oxygen supplies. Nevertheless, within the headquarters you are victims of a trap. You enter a hermetically sealed room whose walls begin to close in on you and you run the risk of being crushed to death. You desperately search for an exit and realize that there is a water pipe that runs across the ceiling. Immediately, you cause the room to flood completely. Now with your oxygen tanks in place you look around and realize with relief that the walls can no longer advance. But, are you completely safe? Could there be some effect on you as the walls push each time with more force?
Objective:
To apply Pascals Principle
Material:
A 20ml syringe
A small balloon
A lighter
Water
Procedure:
1.- Using a piece of balloon make an inflated bubble which can be introduced, inflated into the syringe.
2.- Remove the plunger of the syringe and place the balloon inside. With your finger cover the opening of the syringe, and fill it with water.
3.- Replace the plunger and remove any air that is trapped inside the syringe.
4.- Seal the small opening of the syringe by melting the plastic with the lighter. Be careful to avoid getting burned. Make sure the opening is perfectly sealed.
Questions:
1. What shape did the balloon take on when it was placed in the liquid? Why?
____________________________________________________________________________
____________________________________________________________________________
2. What happens to the balloon when you push the plunger into the syringe? Does the volume of water change? Explain what you observe based on Pascals principle.
____________________________________________________________________________
____________________________________________________________________________
3. What is the relation between the pressure and volume of the air in the balloon?
____________________________________________________________________________
4. What effect does the increase in force applied to the plunger on the balloon and on the internal walls of the syringe? Over which of the two is there more force applied
____________________________________________________________________________
____________________________________________________________________________
5. What is the relation between the force that supports the surface of the balloon and the pressure caused by the plunger?
____________________________________________________________________________
____________________________________________________________________________
6. In the story of the secret agents, why did the walls of the room stop moving in on them?
____________________________________________________________________________
____________________________________________________________________________
7. Do you think the agents would have had reason to be nervous if they had remained trapped much longer between the walls?
____________________________________________________________________________
Experiment 2: Archimedes Principle Materials
clear plastic container, modeling clay, paper towels, water
.
Procedure
1. Fill the clear container three-quarters full of water.
2. Predict whether the ball will sink or float.
3. Drop the ball into the water.
4. Then, remove the ball of clay, dry it, and shape it into a boat.
5. Predict whether the boat will sink or float
Questions
1. Which displaced a greater volume of waterthe clay ball or the clay boat? __________________________________________________________________
2. How did changing the shape of the clay change the buoyant force acting on the clay? ____________________________________________________________________________________________________________________________________
COLEGIO VILLA RICA
JR.HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:_________
LAB PRACTICE # 19
Points of fusion and vaporization
Previous investigation:
1. Who made the first thermometer?
2. What basics did this scientist use to make his thermometer?
3. Describe the first thermometer ever made.
4. What substances do thermometers have for high temperatures?
General information: Its common to think that when water warms up, its temperature increases until it boils, and when it cools off, its temperature diminishes, and finally becomes ice. In order to analyze the change of state of a substance, its advisable to make measurements of the temperature in short periods, while the change is made, and to represent the data graphically to have a clear idea of the evolution of the observed phenomenon.
In this practice, we will analyze the cooling of a substance that does not require of any cooling system to solidify itself. We will also see the utility of graphical representation of an experimental data set to describe a phenomenon. In order to obtain a good representation, its convenient to have an idea of the intervals of temperature and time.
Material:
Metal ring stand
Wire gauze
Iron ring
Utility clamps
250 ml beaker
Bunsen lighter
1 thermometer
1 stopwatch
1 syringe without a needle
Butter or margarine
Procedure:
Part I:
1. Place the ice in the beaker and fill it with water up to 50 or 100 ml.
2. In the table, write down the units used to measure each one of the variables.
3. Register the temperature of water before initiating the heating procedure.
4. Place the beaker on the wire gauze and fix the thermometer with the utility clamp.
5. Light the Bunsen burner and initiate the heating of water. Measure its temperature every 2 minutes and register its value on the table.
6. Next to the table, write down the temperature in which the ice completely melts (fusion point) and the temperature in which the water begins to boil (vaporization point).
Part II:
7. Place butter or margarine in a beaker.
8. Register the temperature of the butter or margarine before initiating the heating procedure.
9. Repeat stages 4-6 above, replacing butter or margarine for ice or water.
TEMPERATURE DURING FUSION AND BOILING POINTS
Time Temperature Temperature
Minutes Celsius Water Celsius Butter
0
2
4
6
8
10
12
14
Part III:
10. Remove the beaker with water from the fire and with a syringe (needle free), fill it up with water and cover the tip with your thumb. Pull the piston back causing a decrease in pressure on the water.
11. What happens to the water when the pressure is diminished? _______________________________
12. Draw a graph with the data in the space below.
Questions:
1. At what temperature did a) the ice melt (fusion)? ______ C b) the butter melt? _______C
2. At what temperature did a) the water boil (vaporization)? _____C b) the butter melt? _____C
3. Convert the above temperatures to degrees Fahrenheit using = (1 . 8 x --- C) + 32
-Point of fusion water ________________ FPoint of vaporization water _______________ F
Point of fusion butter ________________ FPoint of vaporization butter _______________ F
*Observe your graph and answer:
-What happened to the temperature during the final minutes during fusion and vaporization? ____________________________________________________________
____________________________________________________________
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 20
Electric conductivity
Previous investigation: What is electric conductivity? Which materials have great electric conductivity? In cars, in what part is energy taking place?
Objective: to analyze the electric conductivity of different substances and materials
General information: In the 21st century, billions of people rely on electrical energy in one form or another. Today, even in some of the most remote regions, electricity powers lights, radios, televisions, and many other devices that help people to be more productive, comfortable, and informed.
In some places, electricity is generated by hydroelectric dams or coal-fired power plants. In others it comes from self-contained units called "dry cells, also known as batteries. Regardless of its source, the resulting electric current is the same -- it is the flow of electrons through a substance.
In order for electric current to flow, three conditions must be met. One is presence of a substance that allows electrons to move, or flow, easily through it. Such substances, called conductors, are made up of atoms that hold their electrons loosely, allowing them to flow freely to other nearby atoms.
The second requirement is the presence of a power source. Whatever its form, a source of electric current creates what is called a voltage difference, which pushes electrons through the circuit. The chemical reactions inside batteries produce voltage differences between one end of the cell and the other that result in electric current.
Lastly, electric current requires a closed circuit, a length of conducting material connected at each end to a power source that also passes through the "load," the object that makes use of the current. A closed circuit allows a direct, uninterrupted flow of electrons out from the power source and back again in a complete circular connection with no beginning or end.
Material:
2 lemons
3 copper wires
2 large paper clips
2 pennies
a digital clock
scissors
knife
Procedure:
1. First, attach one of the paperclips to a wire.
2. Then attach a penny to a second wire.
3. Attach another penny to one end of the third wire, and a paperclip to the other end.
4. Squeeze and roll two lemons to loosen the pulp inside
5. Make two small cuts in the skins of both lemons an inch or so apart.
6. Put the paper clip that is attached to the wire and the penny into one of the cuts until you get to the juicy part of the lemon.
7. Stick the penny into a hole in the other lemon.
8. Put the other paper clip into the second hole of the lemon with the penny.
9. Then put the last penny into the last open hole.
10. Connect the free ends of the wires to the terminals of the digital clock.
11. Watch how the lemons make enough electricity to turn the clock on. If you've hooked everything up and the clock isn't running, try switching the wires.
12. Here's how this lemon battery works. There's a chemical reaction between the steel in the paper clip and the lemon juice. There's also a chemical reaction between the copper in the penny and the lemon juice. These two chemical reactions push electrons through the wires.
13. Because the two metals are different, the electrons get pushed harder in one direction than the other. If the metals were the same, the push would be equal and no electrons would flow. The electrons flow in one direction around in a circle and then come back to the lemon battery. While they flow through the clock, they make it work. This flow is called electric current.
14. Cut your lemon in half so that the penny is in one half and the paper clip in the other half. The clock should go out, since you've just disconnected the circuit.
15. Now hold one half of the fruit in one hand and your lab assistant's hand in the other. Have your lab assistant hold the other half of the fruit in his or her free hand. Does the clock light up again? It should, since you and your lab assistant are now part of a complete circuit.
16. Make a prediction about how many people the current will flow through and still power the clock.
17. Keep adding lab assistants to the circuit until the clock no longer runs. How do your results compare with your predictions? Is there anything you can do to increase the conductivity (the flow of current) in your circuit of lab assistants?
Questions:
1. What happens to the digital clock when the lemon is cut in half? Why? _____________________________________________________________________________
2. What is a closed circuit? _____________________________________________________________________________
3. What are conductors? _____________________________________________________________________________
4. Do you think human bodies are good conductors? _____________________________________________________________________________
5. Why does the reading on the voltmeter drop as more students join hands? _____________________________________________________________________________
6. How many more kids do you think could be added before the digital clock stops working? ____________________________________________________________________________
COLEGIO VILLA RICAJR. HIGH SCHOOL PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 21
Parallel and series circuits
Previous investigation: What is the importance of electricity. How many forms of electricity are you aware of?
Objective: to observe parallel and series circuits.
General information: An electric circuit is an assembly of conductors and appliances or resistors (loads) in which circulates an electric current. So that the electricity flows through a circuit, electric potential or voltage is required. The intensity with which the current flows through the conductors and resistors is called intensity of current, and its unit is the ampere (A). The resistance that electrical appliances produce in the circuit is measured in ohms ()
Material:
Conductive wire No. 12
1 board of wood 25 x 15 cm
3 1.5 V lights
Lamps or sockets for the lights
A screwdriver
Plug
Electrical tape
Procedure:
1. - Fix 3 lamp sockets to the board in its center leaving a space of 5-10 cm
2. - A team will connect in series the 3 lights on a board using the conductive wire, the plug and the switch as indicated in the illustration. Check that the switch is off and that all the conductive parts are well insulated with the tape, before connecting the apparatus to the current of 110 Volts.
3. - Another team will connect in parallel the 3 bulbs on another board using the same materials as is observed in the illustration.
Answer:
-Close the circuits and observe the luminous intensity of the light In which circuit is it more intense?
Observe what happens when a light in the circuits is disconnected.
*Series: _________________________________________
*Parallel: _______________________________________
-Employing the symbols, draw the diagram that represents each circuit.
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE #22Constructing a Dimmer Switch
Skills Focus: predicting, observing
Previous Investigation
1. What is a variable resistor? __________________________________________________________________
2. How does a dimmer switch work? __________________________________________________________________
Materials
Dcell
masking tape
flashlight bulb in a socket
thick lead from a mechanical pencil
uninsulated copper wire, the same length as the pencil lead
rubber tubing, the same length as the pencil lead
1 wire 1015 cm long
2 wires 2030 cm long
2 alligator clips
Objective
To determine what materials can be used to make a dimmer switch.
Procedure
1. To make a device that can dim a light bulb, construct the circuit shown in the photo on this page. To begin, attach wires to the ends of the D-cell.
2. Connect the other end of one of the wires to the bulb in a socket. Attach a wire with an alligator clip to the other side of the socket.
3. Attach an alligator clip to the other wire.
4. The pencil lead will serve as a resistor that can be varieda variable resistor. Attach one alligator clip firmly to the tip of the pencil lead. Be sure the clip makes good contact with the lead. (Note: Pencil lead is actually graphite, a form of the element carbon.)
5. Predict how the brightness of the bulb will change as you slide the other alligator clip back and forth along the lead. Test your prediction.
6. What will happen to the brightness of the bulb if you replace the lead with a piece of uninsulated copper wire? Adapt your pencil-lead investigation to test the copper wire.
7. Predict what will happen to the brightness of the bulb if you replace the pencil lead with a piece of rubber tubing. Adapt your pencil-lead investigation to test the rubber tubing.
Analyze and ConcludeWrite your answers in the spaces provided or on a separate sheet of paper.
1. Controlling VariablesWhat variable did you manipulate by sliding the alligator clip along the pencil lead in Step 5?
2. ObservingWhat happened to the brightness of the bulb when you slid the alligator clip along the pencil lead?
3. PredictingExplain your reasoning in making predictions about the brightness of the bulb in Steps 6 and 7. Were your predictions supported by your observations?
4. Interpreting DataDo you think that pencil lead has more or less resistance than copper? Do you think it has more or less resistance than rubber? Use your observations to explain your answers.
5. Drawing ConclusionsWhich material tested in this lab would make the best dimmer switch? Explain you answer.
6. CommunicatingSuppose you want to sell your dimmer switch to the owner of a theater. Write a product information sheet that describes your device and explains how it works. (Use a separate sheet of paper to answer.)
More to Explore
The volume controls on some car radios and television sets contain resistors that can be varied, called rheostats. The sliding volume controls on a sound mixing board are rheostats as well. Homes and theaters may use rheostats to adjust lighting. Where else in your house would rheostats be useful? (Hint: Look for applications where you want to adjust a device gradually rather than just on or off.)
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 23
Steadiness Tester
Previous Investigation: 1. What three conditions are required for an electric current to flow? ______________________________________________________________________________________________________________________________________________________________________________________________________
Objective: To design a game which teaches the basic conditions of circuits.
General Information: The steadiness tester you will make today fulfills all of the requirements of an electric circuit -- so long as the person being tested is less than steady. This last requirement, in fact, is the one that allows the device to function as a steadiness tester. In other words, the steadiness tester operates only when you accidentally touch the inside of the wire loop to the tester. This action closes the circuit, causing electricity to flow and the alarm to sound.
Material:
wire coat hanger
sandpaper
aluminum foil
2 D batteries
tape
12" x 12" piece of cardboard
red and black electrical wire
buzzer
Procedure:
1. Remove the cardboard from a wire coat hanger. Untwist it.
2. Use sandpaper to remove the coating on the hanger. This may take a while to do. Sanding the coat hanger makes it easier for electricity to pass from the coat hanger to anything metal that touches it.
3. Make three flat strips and a long loop out of aluminum foil.
4. Connect the two D batteries with one of the strips of foil. Be sure to connect the plus (positive) side of one battery to the minus (negative) side of the other so that electricity can flow between them.
5. Tape the other two strips of foil to the other sides of the batteries.
6. Tape one end of the hanger onto a piece of cardboard. The rest of the hanger should be sticking up from the cardboard.
7. Attach the aluminum foil that leads to the positive side of the battery to the hanger, making sure that the two metals are touching. Tape the black wire of the buzzer to the aluminum foil that leads to the negative side of the battery.
8. Tape the red wire and the aluminum foil loop together.
9. Now everything is connected! See if you can move the loop of aluminum foil all the way along the coat hanger without buzzing. If you're not steady when you put the loop around the hanger, you will complete the circuit (the path that the electricity flows along) and the buzzer will buzz. The electricity can flow because all the materials in the circuit (conductors) are made of metal.
10. How steady are you? If it's too easy or too hard you can redesign the path of the coat hanger or change the size of the aluminum foil loop.
Questions:
1. What is a conductor? __________________________________________________________________
2. Make a drawing of the steadiness tester game. Label the parts of the electric circuit that are conductors. Why must there be conductors to make the game work?
3. What other materials could be used to make a steadiness tester? Would a steadiness tester work if it were made out of plastic? __________________________________________________________________
4. Can you think of another game that uses an electric circuit? Describe the circuit and how it is completed or interrupted as part of the game. ______________________________________________________________________________________________________________________________________________________________________________________________________
5. Can you invent your own game that uses an electric circuit? ______________________________________________________________________________________________________________________________________________________________________________________________________
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 24
Construction of an electromagnet
Previous investigation: Explain why a compass needle points to the North. Explain how you can find out the north pole of a magnet.
Objective: To observe magnetization by electric current. To verify that an electric current produces a magnetic field..
General information: Many routine appliances, like bells, motors or loudspeakers convert electricity into magnetism. The physicist Hans Christian Oersted carried out an experiment in 1820 that modified the concepts of electricity and magnetism that had been held up until then. Oersted observed that an intense electric current, allowed to circulate through a wire, changed the direction of the needle on a nearby compass. He understood that the deviation of the needle was an effect of the magnetism produced by the current, thus discovering electro- magnetism.
Material:
10 m of insulated copper wire #18.
One cardboard tube from a toilet paper roll.
One 5 cm bar magnet
One multimeter
Procedure:
1.- Wrap the copper wire around the cardboard tube as many times as possible. Try to make two or more layers. The ends of the wire should remain exposed without insulation. This tube wrapped in wire is called the induction coil.
2.- Adjust the multimeter to measure the direct current in milliamps and connect it to the free ends of the induction coils wire.
3.- Pass the magnet quickly through the inside of the cardboard tube so that the poles of the magnet remain inside the coil. Observe the reading of the multimeter.
4.- Maintain the magnet at rest inside the coil. Register the reading of the multimeter.
5.- Remove quickly the magnet from the bobbins interior. Observe the reading of the multimeter. Move the magnet closer to and then farther away from the coil, varying how quickly it is moved. Each time register the reading of the multimeter.
questions:
1. What was the reading of the multimeter when the magnet was placed inside the induction coil?
____________________________________________________________________________
2. What was the reading you obtained when you left the magnet resting inside the coil?
____________________________________________________________________________
3. What difference was there between the previous readings and those the multimeter registered when you moved the magnet close and then farther away over and over again? What did you observe when you varied how quickly you made these movements?
____________________________________________________________________________
____________________________________________________________________________
4. When you moved the magnet in and out of the induction coil a current was generated that could, for example, light a small light bulb. In other words, it obtained energy. According to the principle of conservation of energy, energy is neither created nor destroyed but only transformed. From where do you think the coil obtained this energy?
____________________________________________________________________________
5. What kind of energy was obtained by the coil?
____________________________________________________________________________
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 25
Light and its Effects
Previous investigation: What is the electromagnetic spectrum and where is visible light located in the spectrum?
Objective: To observe dispersion and the effects on light while combining colors.
General information: We know that light behaves as a wave that bends due to changes in speed. Light is diffused in all directions in space and each one of these directions is called a ray. This is very common to see when we are in the interior of a dark room and between the door and the wall there is a small opening. We are able to observe that the light passing through this opening is bent and so diffuses. Experience also shows us that the propagation of the light in a same medium is straight and uniform but when light passes into a different medium the behavior of the light ray changes as well. It can speed up or change direction, for example.
Material:
20cm paper towel roll
3 mirrors each the length of the roll and a width smaller than the diameter
Sheet of cardboard or foamy
Transparent material (glass, Lucite, plastic, etc)
Colorful beads, glass, gems, marbles, etc.
Glue
Scissors
Flashlight
Experiment 1
Procedure:1. - Shine the beam of light from the flashlight onto one of the faces of the prism until the light be scattered in a colored band (spectrum) in which the colors of the rainbow appear. *Illustrate:
Circle the correct answer.
1. White light is the combination of: A. Blue and green C. All colorsB. Yellow and BlackD. No color
2. Due to the fact that objects of a specific color only reflect the light of its same color, we can say that a white object reflects: A. Only white lightC. Light of any colorB. No colorD. Green, red, and blue light
Experiment 2
Construction of a Kaleidoscope
Procedure:
1. Obtain a paper towel tube cut eight inches (20 centimeters) long
2. Cut three pieces of mirror almost as long as your tube. The width of each mirror strip should be the same---and must measure LESS than the tube's diameter.
3. Here is the correct pattern of overlap for mirror strips.
4. Make a long, equilateral triangular tunnel of the mirror strips---mirror surface facing the INSIDE of the tunnel. Secure the mirror tunnel by wrapping tape around the outside.
5. Slip the mirror tunnel inside your tube.
6. Close the viewing end. Cover one end of your tube with a disc of cardboard or foamy with a viewing hole cut in the center. Secure this with glue.
7. Now make your object chamber. Cut two disks of transparent material (glass, Lucite, Lexan, etc) to match the diameter of your tube.
8. Next, cut a one-inch strip of lightweight cardboard a little longer than the circumference of your tube and curl it around, gluing the ends, to make a circle that matches the diameter of your tube.
9. Let the glue set up. Now glue this to one of the transparent circles to make a little cup. Let that glue set up.
10. Fill and close the object chamber. Find some colorful beads, bits of colored glass, costume jewelry "gems", marbles or whatever. These should be small, brightly colored and transparent.
11. Put them in the cup (object chamber) but don't overfill. There should be room for the objects to tumble around and form changing patterns. Glue the other transparent disk on top to close the chamber.
12. When the glue has dried, attach the object chamber to the end of your tube.
Light travels in a straight line through empty space, but when it bumps into an object, it changes direction. Some shiny surfaces, like the plastic report cover or a mirror, send or reflect light back to you. (Think of a ball bouncing off a wall.) The sides of the plastic tube inside the kaleidoscope reflect the beads, sequins, and confetti. The reflections bounce back and forth from side to side creating multiple images. When you turn the kaleidoscope, the pieces move, and you see a different design.
Adapted from: http://kids.nationalgeographic.com/Activities/FunScience/Be-dazzled, http://www.kaleidoscopesusa.com/makeAscope.htm
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 26
The Phenomena of Light: Looking at Images
Previous investigation: What is light? How does it propagate? Does light need something in which to propagate? What phenomena does light present?
Objective:
How does the distance between an object and a convex lens affect the image formed?
Skills Focus:
controlling variables, interpreting data
Materials:
tape
convex lens
cardboard stand
blank sheet of paper
light bulb and socket
clay, for holding the lens
battery and wires
meter stick
Procedure:
1. Tape the paper onto the cardboard stand.
2. Place a lit bulb more than 2 m from the paper. Use the lens to focus light from the bulb onto the paper. Measure the distance from the lens to the paper. This is the approximate focal length of the lens you are using.
3. Record your data in the data table.
4. Now place the bulb more than twice the focal length away from the lens. Adjust the cardboard until the image is focused. Record the size of the image on the paper and note the orientation of the image. Record the distance from the bulb to the lens and from the lens to the cardboard.
5. Now, move the bulb so that it is just over one focal length away from the lens. Record the position and size of the image.
Light
Data Table
Analyze and Conclude
1. Controlling Variables Make a list of the variables in this experiment. Which variables did you keep constant? Which was the manipulated variable? Which were the responding variables? An example is shown below to help you complete the chart.
Variable
Constant?
Manipulated?
Responding?
Focal length
x
2. Observing What happened to the position of the image as the bulb moved toward the lens? _______________________________________________________________________________
3. Interpreting Data Was the image formed by the convex lens always enlarged? If not, under what conditions was the image reduced? _______________________________________________________________________________
4. Predicting What would happen if you look through the lens at the bulb when it is closer to the lens than the focal point? Explain your prediction. _______________________________________________________________________________
5. Communicating Write a paragraph explaining how the distance between an object and a convex lens affects the image formed. Use ray diagrams to help you summarize your results. _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
55
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 27
How Do Colors Mix?
Skills Focus: Observing
Previous Investigation:
1. What color would you get if you combine blue and yellow paint? _______________________
2. What color would you get if you combined blue and yellow light? _______________________
General Information: A wide range of colors can be produced using just a few basic colors of light.
Three colors that can combine to make any other color are called primary colors. Two primary colors combine in equal amounts to produce a secondary color. The primary colors of light are red, green, and blue. The secondary colors of light are yellow (red + green ), cyan (green + blue), and
magenta (red + blue). When all three primary colors of light are combined in equal amounts, they produce white light. If the three primary colors of light are combined in different amounts, they can produce other colors.
Complementary colors are a primary color and a secondary color that can combine to form white light. Blue and yellow are examples of complementary colors.
Materials:
white cardboard, metric ruler, scissors, markers (red, green, and blue), 1m of string
Procedure
1. Cut a disk with a diameter of 10cm out of white cardboard. Divide the disk into three equal-sized segments. Color one segment red, the next green, and the third blue.
2. Carefully punch two holes, 2cm apart, on opposite sides of the center of the disk.
3. Thread a 1-m long string through the holes. Tie the ends of the string together to make a loop that passes through both holes.
4. With equal lengths of string on each side of the disk, tape the string in place. Turn the disk to wind up the string. Predict what color(s) you will see if the disk spins fast.
5. Spin the disk by pulling the loops to unwind the string.
Questions:
1. What color do you see as the wheel spins fast? ________________________________________________________________________
2. Was your prediction correct? _______________
3. Three colors that can combine to make any other color are called ________________________________________________________________________
4. When two primary colors combine in equal amounts, they produce a ________________________________________________________________________
5. Any two colors that combine to form white light are called ________________________________________________________________________
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 28
Construction of a Telescope
PREVIOUS INVESTIGATION:
How many types of telescopes have you heard of?
____________________________________________________________________________
____________________________________________________________________________
How many types of telescopes are there?
____________________________________________________________________________
____________________________________________________________________________
introduction:
The telescope is an instrument used to make distant objects appear closer. Its origins date back to the 16th century in the Dutch city of Middelburg where the children of a lens manufacturer named Hans Lippersshey (1570-1619) would play with the lens their father made. On one occasion they had the idea to look at a weather vane on top of a bell tower through the lens, placing one in front of the other. When they realized that the weather vane looked as though it were closer they shared their discovery with their father. To facilitate the observation of faraway objects, at first Lippershey attached them to a board and placed them at the ends of two organ tubes that slid one inside the other. With that, he created the first optic telescope. There still is some uncertainty, however, about who actually was the first to invent the telescope, as there have been stories of a "magical" telescopic device dating as early as the sixteenth century. Lippershey is, at least, generally considered the first person to describe a telescope in writing.
Objetive:
To construct a telescope and explore some of its characteristics.
Material:
Two 1.5 liter empty plastic bottles
A magnifying glass approximately the same diameter as the base of the bottle.A smaller magnifying glass, approximately the diameter of the bottles opening or a photographic camera that no longer works.
Scissors
Adhesive tape
Metric measuring tape
Calipers
Procedure:
1.- On a clear day go outside, place each lens in a horizontal position and bring it closer and move it farther away from the ground until you can concentrate the suns rays passing through the lens in one point. Once you have accomplished this, measure the distance between the shiny dot and the center of each lens and record this longitude, which is the focal distance of the lens. See drawing below.
2.- Use the caliper to measure the diameters of the lenses and record your answer.
3.- Fit the small lens into the mouth of the bottle and hold it in place with the adhesive tape. Use the scissors to cut the base of the bottle.
4.- Cut the second bottle at its base and also near its top where the bottle begins to narrow in such a way as to obtain a cylinder. Next, cut the length of the cylinder.
5.- Attach the large lens at one end of the cylinder and insert the other end into the first bottle.
6.- Now remove the cylinder from the bottle and tape it back together where you first made the cut down its length, being sure to slightly overlap the edges so the cylinder is rigid.
7.- Once again insert the cylinder into the bottle in such a way as it can slide in and out. Your telescope is ready! Be sure that the distance between the lenses is less than the sum of the focal distances.
8.- Go outside and observe distant objects with your telescope. Slide the cylinder in and out to focus on an object. Do not use your telescope to directly look at the sun.
questions:
1. Make several observations of objects and estimate how close they are to your telescope. One way to do this is to observe an object with the telescope and then get closer to it until you can see in plain sight the same details that you saw with the telescope. The distances to the object from the place where you observed it with the telescope and from the point where it looked the same in plain sight can be used to give a closeness reading.
____________________________________________________________________________
____________________________________________________________________________
2. One of the most important characteristics of telescopes is the magnification of the observed object. In a telescope, the objective lens is the one directed at the observed object and the ocular lens is the one that is closer to the observers eye. The magnification of a telescope is the calculation of the focal distance of the objective lens and the focal distance of the ocular lens. Calculate the magnification of your telescope and compare your result with the estimate that you made in the previous question.
____________________________________________________________________________
____________________________________________________________________________
3. The aperture of a telescope determines its ability to capture light which allows the observation of objects with more detail and is related to the diameter of the objective lens. This characteristic is measured with a focal calculation which is the calculation between the focal distance of the objective lens and its diameter. What is the focal calculation of your telescope?
____________________________________________________________________________
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 29
Changing Colors
Skills Focus: observing, inferring, predicting
Objective:
Stage lighting in theaters uses color filters to control the colors of light on stage. In this lab, you will study the effect of color filters on white light.
Materials:
shoe box
scissors
flashlight
removable tape
red object (such as a ripe tomato)
yellow object (such as a ripe lemon)
blue object (such as blue construction paper)
red, green, and blue cellophane, enough to cover the top of the shoe box
Problem
How do color filters affect the appearance of objects in white light?
Procedure
1. Carefully cut a large rectangular hole in the lid of the shoe box.
2. Carefully cut a small, round hole in the center of one of the ends of the shoe box.
3. Tape the red cellophane under the lid of the shoe box, covering the hole in the lid.
4. Place the objects in the box and put the lid on.
5. In a darkened room, shine the flashlight into the shoe box through the side hole. Note the apparent color of each object in the box.
6. Repeat Steps 35 using the other colors of cellophane.
Analyze and Conclude
1. ObservingWhat did you see when you looked through the red cellophane? Explain why each object appeared as it did. ________________________________________________________________________________________________________________________________________________
2. ObservingWhat did you see when you looked through the blue cellophane? Explain. ________________________________________________________________________________________________________________________________________________
3. InferringWhat color of light(s) does each piece of cellophane allow through? ________________________________________________________________________
4. PredictingPredict what you would see under each piece of cellophane if you put a white object in the box. Test your prediction. ________________________________________________________________________________________________________________________________________________
5. PredictingWhat do you think would happen if you viewed a red object through yellow cellophane? Draw a diagram to support your prediction. Then test your prediction. ________________________________________________________________________________________________________________________________________________________________________________________________________________________
6. CommunicatingSummarize your conclusions by drawing diagrams to show how each color filter affects white light. Write captions to explain your diagrams.
COLEGIO VILLA RICA
JR. HIGH SCHOOL
PHYSICS LABORATORY
Name:_________________________________ Date:__________________ Group:__________
LAB PRACTICE # 30
Construction of a periscope
Previous investigation: State the law of reflection. If the surface where a ray of light enters is curved, does it still follow the law?
Objective: To explain the law of reflection by constructing a periscope.
General information: When a ball bounces against a wall , its path changes; this same thing occurs with light rays when they collide with a surface and are not absorbed.
Reflection is the change of direction that light rays experience when they collide with a surface.
When light strikes a surface, the rays of light are reflected or they bounce. The surfaces that best reflect light are smooth and polished. The smooth surfaces that provide the clearest reflections are mirrors. These are made of a flat sheet of glass and a thin layer of shiny material such as silver, aluminum, tin or mercury..
Material:
1 empty carton of milk
2 plain mirrors
Scissors
Tape
Procedure:
-Cut along three edges of the face of a cardboard milk container and open it. Carefully cut two small square windows as shown.. Stick with adhesive tape the two mirrors inside the container. They should be parallel and centered with regard to the windows. Apply some adhesive tape for the lower window.
Questions:
1. Why is it possible for you to observe what happens in the front window by looking through the rear window? _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
2. What type of image do you see? _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
3. If you wanted to bring the image closer, what type of lens would you use? _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Bibliography
Hctor H. Romo, Vctor V. Delgado, J.Bls I. Terrazas, Aurora Licona . Fsica 3 . Editorial CASTILLO. Mxico 2000
Alejandro Corts Jurez, Yoshino Kamichika Kohashi. Fsica Creativa 3. Editorial FERNANDEZ editores. Mxico 2001.
Vctor Manuel Lozano Carranza, Roberto Sayavedra Soto. Prcticas de Fsica 3. Editorial SANTILLANA. Mxico 2000
Francisco de la Torre, Alicia Flores Escobar. El Mundo de la Fsica 2. Editorial PROGRESO. Mxico 2003.
Paul G. Hewitt, David Riveros, Evelina Chiu. Las Reglas de la Naturaleza. Editorial PRENTICE HALL. Mxico 2005.