unit 8 guided notes

Guided Notes for Unit 8: Electricity and Magnetism

Lesson 1: Electric Charge Objectives

Describe how charged objects experience forces of attraction or repulsion.

Explain that objects become electrically charged when they gain or lose electrons.

Describe the area where one or more charged particles exert a force on another charge as an electric field.

KEY TERMS/QUESTIONS MAIN IDEAS & DEFINITIONS

How Do Electric Charges Interact?

Question: Where do electric charges come from? Question: What happens when charges “meet?”

Atomic Particles Have Electric

Charges

Question: a) How many protons are in this

Chorine atom? b) How many electrons? c) Is it an ion or a neutral atom? d) What is the atom’s total

charge?

Answer: Electric charges come from specific parts of an _______.

Every atom has a ___________

It contains ________________ charged protons

The __________ is surrounded by ______________ charged

electrons

Answer: Opposite charges _______________ each other

o This “force of attraction” is the same one that keeps

negatively charged ________________ attracted to, and

orbiting the _______________ nucleus of an atom.

Like charges _____________ each other.

Atoms consist of CHARGED particles

Each electron has a charge of:_____

Each proton has a charge of: _____

You can ADD these together (or subtract if need be)

Atoms are NEUTRAL (no charge) when __________ equal

____________

Atoms with unequal numbers of charged particles are called ______

o Ions are positive when there are more _________ than

electrons

o Ions are negative when there are more _________ than

protons

Answer:

a)

b)

c)

d)


Large Objects Have Electric Charges

Question: Can objects besides atoms have electric charges? Question: Provide an example

Question: Is the force of electric charge greater than gravity? Explain. Question: If you rubbed two balloons with wool cloth and held them close together, what would happen? Electric Fields

Key Word: Electric Field

Electric Force

Question: How can you change the electric force between two charged objects? Question:

a) What happens when the charge increases?

b) What happens when the distance increases?

Answer: Yes. Everyday objects can also have electric charges.

This occurs when the atoms of the object ________ or _______

electrons.

Example: Balloon rubbed with wool.

_________ move from atoms in the ________ to atoms in the

_________

The balloon takes on a _____________ charge.

Close to the wall, the electrons in the balloon ___________ the

electrons in the wall, leaving the __________ on the wall’s

surface.

The wall surface is now _______________ charged.

Because they are oppositely charged, the balloon is

_____________ ____ to the wall.

Answer:

Answer: DEFINITION: the _________ throughout a _________due to one or

more ________________ __________ particles or surfaces

The __________ of a particles’ electric __________ on other

objects depends on the objects’ ______________ from the

charge.

The field is ___________ at a point ____________ to the charge

than it is at a point _______ away.

So, the effect of two charges on one another _______________ as the charges move ____________ apart.

Answer: The electric force between two charges (or charged objects) depends on two things:

1. Amount of ________________ on each object and 2. The ____________________ between the objects/charges

Answer:

a) As charge increases, electric force ____________ b) As distance increases, electric force ______________


Question: Why do two balloons similarly charged need to be close together to repeal each other?

Where Do the Electrons Go?

Question: When you comb your hair on a dry day, why do some of your hair strands appear to float apart? Question: Why do clothes stick together in the dryer?

Electroscope

Key Word: Electroscope

Question: How can you tell if an object is electrically charged?

What Happens to Electric Charges?

Key Word: Electric Current

REMINDER:

Answer: Electrons are free to move.

Some objects take on electrons easily Some give up electrons easily

Answer:

Answer:

DEFINITION: an instrument for detecting _________ electricity

Answer: When you touch a charged object to the electroscope, the

____________ will move into (or out of) the scope and give the

“leaves” of the electroscope the same charge.

Since the leaves have like charges, they will _________

____________ Electric charges can either _______ ___ on the surface of an object,

or they can ________

When charges build up, we call this ____________ electricity

When charges move, we call this _____________ ________

Example(s):

DEFINITION: the ___________ of electrons through a wire (or other

material)

Please complete the lesson review for lesson 1 in your student pages.


Lesson 2: Electric Currents Objectives

Define electric current and electricity as a flow of charged particles (such as the flow of electrons in a

wire).

Explain how electric resistance affects current.

Identify materials as conductors or insulators of the flow of electricity.


Conductors Carry Currents

Key Word: Conductor

Question: Why do metals make good conductors?

Insulators Stop Currents

Key Word: Insulator

Question: How is an insulator like a dam?

Question: Are all non-metals good insulators?

Resistance and Electrical Currents

Question: Is there such a thing as a “perfect” insulator – something that can stop ANY current, no matter how large?

Key Word: Resistance

Question: When electrons encounter resistance and slow down, WHERE does their energy go? Question: Can resistance be dangerous?

DEFINITION: Any material through which electricity _____ ______.

Example(s):

Answer:

DEFINITION: A substance that ________ conduct electricity very well.

Example(s):

Answer: Answer: Answer: Yes/No (Circle One) Explain:

Even excellent conductors will _______ ________ electric current

Even excellent insulators will allow __________ to flow if they

become “overwhelmed”

DEFINITION: the quality of a substance that __________ the flow of

electrons through it

ALL materials ___________the flow of electrons to some degree

(conductors less than insulators) As electrons encounter resistance, they ________ _______

Answer: The energy is converted to ____________ Examples of household devices that use resistance:

Answer: Yes/No (Circle One)

Explain:


What Makes Electricity Flow?

Question: What are some ways we can make electricity flow by creating this electrical “potential”?

Can Electrons Be Used Up?

Keeping Electrons on Track

REMINDER:

Because electrons repel one another and are attracted to objects

with a positive charge, they will flow from negative to _________

So, in order to create current, you must first find a way to create

this DIFFERENCE in ___________

This is called an electrical “potential” (which we also known as

“voltage”)

Answer/Examples:

Answer: Yes/No Explain: Electrons never disappear, but they can reach a _______ ____

and stop ___________ (we say they are no longer “free” to move)

As you now know, electricity flows in a _________ and can be used to

do ________, such as lighting a light bulb.

Take a look around you. Name at least 5 things around you that are

powered by electric currents: 1. 2. 3. 4. 5.



Lesson 3: Electric Circuits Objectives

Interpret and compare diagrams of open and closed electric circuits, including series and parallel circuits.

Analyze and label the parts of an electric circuit.

Explain how electric current flows in series and parallel circuits and describe the advantages and disad-

vantages of each type of circuit.

Describe an electric circuit as a complete closed path for an electric current.

Explain how electric resistance affects current.


Circuits: Keeping the Flow

Question: How are electrons flowing in a current like the chimpanzees in a line?

Key Word: Electric Circuit

Circuits: Not Just a Bunch of Wires

Question: How do you get electrons to begin flowing in the first place? Question: Which way do the electrons flow?

Answer: CIRCUITS:

An electrical current can only exist if electrons are ________.

The current needs a medium, or _____________, through which to

flow.

Because the conductor always has some ________________

electrons continue to flow only if a constant ___________ is

pushing on them.

If the conductor ends at the same place it begins, the force of

___________________ will continue to keep the electrons moving.

DEFINITION: a continuous, looped ___________ ____________

around which electricity flows

Answer: you need a source of ___________ that will _______ into the

loop and cause the current to flow.

A common source of electrons is a _____________

Batteries store two different chemicals:

One tends to ________ electrons

The other tends to ________ them

This creates an ____________ field, with one pole being more

______________ and the other being more _____________

When a conductor (like a wire is connected to the two poles), the

electrons naturally begin to flow

Answer: Electrons ALWAYS flow from ___________ to __________


Resistors: Resisting The Flow

Question: When resistance increases, what happens to current flow? Question: How can you tell if you’ve successfully created a simple circuit (is current flowing)?

Switches Stop The Flow

Series vs. Parallel Circuits

Question:

1. When might you want to use a parallel circuit, rather than a series circuit?

2. When might a series circuit be better than a parallel circuit?

REMINDER

Answer: Just like a clogged pipe that won’t let much water through, a

material with high resistance won’t let much _________ flow either.

As resistance increases, current flow __________

As resistance decreases, current flow __________

Answer: An easy way to test your work is to include a __________ of

the right kind in the circuit. You will know electricity is flowing because

the resistance in the circuit will cause energy to be converted into

_______ or _______

Example:

An electric charge needs a _________ circuit to flow.

Switches can be used to control the flow of electrons by _________

and __________ the circuit

When a circuit is open, electrons ___________ flow.

Answer: Series Circuit vs. Parallel Circuit: 1. SERIES:

o Uses _______ continuous wire

from the battery through the light

bulbs.

o GOOD: All current flows through

EVERY device – full power is

delivered

o BAD: If any ONE bulb burns out,

however, then the circuit is _________ and ALL bulbs/devices will

go out.

2. PARALLEL:

o Has _______ sets of wires,

creating multiple paths through

which current can flow.

o GOOD: If one bulb burns out,

will the circuit be broken?

Yes/No (Circle one)

o BAD: The current DIVIDES (like water flowing past islands), so

each device has less overall power.



Lesson 6: Magnetism Objectives

Identify materials that are magnetic.

Explain a diagram that shows the lines of force in a magnetic field.

Compare a magnetic field with an electrical field

KEY TERMS/QUESTIONS MAIN IDEAS & DEFINITIONS Fill in the blanks: Magnetic fields Key Word: magnetic poles

Question: What happens to the poles when you cut a magnet in half? Key Word: dipolar

Fill in the blanks: Magnetic poles

Magnets exert a force of _______________________, which means they

push other magnets away. Magnets also exert a force of

________________, which means they attract other magnets and certain

types of metals.

DEFINITION:

The two ends of a magnet, where the _________________

________________ is especially strong. Bar magnets have _______

magnetic poles.

Answer:

DEFINITION:

an object with two sides that have ___________________________

characteristics

Notes:

Unlike poles _____________________________one another, and

like poles _______________________ one another.

Lesson 4: Your Choice (Just mark this complete in the OLS) Lesson 5: LAB: Series and Parallel Circuits (Student Pages 361-364) Objectives

Explain how electric current flows in series and parallel circuits and describe the ad-

vantages and disadvantages of each type of circuit.

Create parallel and series electric circuits.

Interpret and compare diagrams of open and closed electric circuits, including series and

parallel circuits.

Analyze and label the parts of an electric circuit.


Key Word: domains

Key Word: Permanent magnets

Key Word: Temporary magnets

Question: How do you make a nail magnetic? Key Word: magnetic field

Question: How does a compass work? Reminder:

DEFINITION:

a small region in which _______________________________ atoms that

have magnetic fields _______________________________ with their

magnetic fields oriented in the ____________________________ direc-

tion

DEFINITION: Permanent magnets are made in a

_________________________ with all their ____________________

material _____________________________ more in one direction than

others. Their overall magnetic force is strong and they are unlikely to go

back non-magnets.

DEFINITION:

They behave like magnets only when in the presence of _______________.

These items alone do not exert a discernible _________________

____________________.

Examples are:

Answer:

DEFINITION:

The ____________________ around every magnet where the magnetic

___________________ can be felt. Magnets ______ ______ have

to touch an object to exert a force on it. The force is ________________

near the poles and becomes ______________________ further away from

the poles.

Answer:



Lesson 7: Electricity and Magnetism Objectives

Explain how a magnetic field can be created by an electric current flowing in a wire.

Describe how different variables influence the strength of an electromagnet.

KEY TERMS/QUESTIONS MAIN IDEAS & DEFINITIONS Remember: Permanent magnets are

usually made in a factory with all

their domains aligned. Temporary

magnets behave like magnets only

when they are near permanent

magnets.

Key Word: electromagnetic

Question: Why wouldn’t a permanent magnet work in a salvage yard where they need to pick up and release metal?

Question: How can you make an electromagnet?

Notes: A simple electromagnet like

the one shown, typically consists of

3 main parts:---------------------

List:

Permanent magnet:

Temporary magnet:

DEFINITION:

A ____________________________ magnet made using

_______________________ ___________________, usually running

around a _____________________core. As long as electric charges are flowing through the wires, the electromagnet holds the metal tightly. The electric current stops flowing through the wire, and the magnetic field disappears.

Answer:

Answer:

1. ____________________ ___________________: such as a

battery

2. ____________________ ___________________: such as an

iron nail or screw

3. ____________________: coiled around the metal core, and con-

nected to the battery to carry the electric current


Notes: The strength of an

electromagnet depends on two

factors. List them to the right and

give details about how to create

those factors.

Key Word: galvanometer

Question: How can you make one?

Reminder:

Notes:

1.

2.

DEFINITION: an instrument that uses a movable ________________

_________________ to detect the _______________________

magnetic

field around an ________________________ current.

Answer:

Please complete the lesson review for lesson 7 in your student pages. Please also do the investigation about creating an electromagnet.

Lesson 8: LAB: Motoring On (Student Pages 381-386) Objectives

Create an electric motor


Lesson 9: Motors and Generators Objectives

Describe how an electric current is created when a circuit is exposed to a changing mag-

netic field.

Explain how generators convert mechanical energy into electrical energy.

KEY TERMS/QUESTIONS MAIN IDEAS & DEFINITIONS Key Word: motor

Notes: How a motor works Key Word: generator

Questions: To generate large amounts of electricity, generators rely on powerful sources of mechanical energy. What are examples of some of these sources?

Reminder:

DEFINITION:

a machine that converts ______________________ energy into

______________________ energy

Notes:

The electric current _________________________the coil, which then

turns as the coil’s magnetic field is _______________________ and

______________________________to the stationary magnets.

DEFINITION: Electric generators ______________________mechanical

energy into _______________________________energy. By applying a

mechanical force to turn the rod, the coil becomes

_____________________________ and generates an

_________________________ current.

Answer/Examples:

Please complete the lesson review for lesson 9 in your student pages. Please also do the investigation about generators in history.

Lesson 10-12: Unit 8 Model Problems, Review and OLS Assessment

unit 8 guided notes

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