MagnetsWhat is a magnet? A magnet is a body which attracts iron, combinations of

metals (known as alloys) or other materials which are composed of iron or iron-like substances. "Attract" means an object composed of iron will attach or affix itself to the magnet. Additionally, the magnet can "magnetize" other objects which in turn act like magnets. Other iron objects will be attracted to the magnetized object.

The two ends of the magnet are different and are referred to as the north and south pole (or north-seeking pole and south-seeking pole). Like poles repel. The south poles of two magnets will not attract one another. Neither will the north poles of two magnets. The north pole of one magnet and the south pole of another magnet will attract one another.

Like Poles Repel – Unlike Poles Attracthttp://www.swe.org/iac/lp/magnets_03.html

Bar MagnetMAGNETS AND ELECTRICITY In most objects, all of the forces are in balance. Half of the electrons are spinning in one direction; half are spinning in the other. These spinning electrons are scattered evenly throughout the object.

Magnets are different. In magnets, most of the electrons at one end are spinning in one direction. Most of the electrons at the other end are spinning in the opposite direction.

This creates an imbalance in the forces between the ends of a magnet. This creates a magnetic field around a magnet. A magnet is labeled with North (N) and South (S) poles. The magnetic force in a magnet flows from the North pole to the South pole.

Have you ever held two magnets close to each other? They don’t act like most objects. If you try to push the South poles together, they repel each other. Two North poles also repel each other.

Turn one magnet around and the North (N) and the South (S) poles are attracted to each other. The magnets come together with a strong force. Just like protons and electrons, opposites attract.

These special properties of magnets can be used to make electricity. Moving magnetic fields can pull and push electrons. Some metals, like copper have electrons that are loosely held. They can be pushed from their shells by moving magnets. Magnets and wire are used together in electric generators.

http://www.eia.doe.gov/kids/energyfacts/sources/electricity.html

Magnets

A magnet has two poles, called North and South.A magnetic field is a region around the magnet

where magnet materials experience a force.There are only three magnetic elements, iron, nickel and cobalt.

In practice you will only use iron,or steel which is an alloy of iron

The shape of the magnetic field around the magnet is shown by lines.Arrows on the lines point away from North and towards South

to show the direction of the magnetic field.

Notice that the lines of magnetic force do not cross each other.The closer together the lines are, the stronger the field is.

You need to know the shape of the magnetic field for a bar magnet,poles which attract and poles which repel.

The magnetic field can be seen by placing the magnetunder a piece of paper with small iron filings on top.

The filings line up in the shape of the field, as shown above.

The direction of the arrows can be seen by placing a compass in the field.The compass points in the direction of the arrows,

away from North and towards South.Note - this means that when a compass points to the Earth's North Pole,

there must be a magnetic South Pole up there(bet that confuses the penguins!). http://www.gcsescience.com/pme1.htm

The Loop

Closed Vs. Open Circuit

Loads

BATTERIES PRODUCE ELECTRICITYA battery produces electricity using two different metals

in a chemical solution. A chemical reaction between the metals and the chemicals frees more electrons in one metal than in the other. One end of the battery is attached to one of the metals; the other end is attached to the other metal. The end that frees more electrons develops a positive charge and the other end develops a negative charge. If a wire is attached from one end of the battery to the other, electrons flow through the wire to balance the electrical charge. A load is a device that does work or performs a job. If a load––such as a light bulb––is placed along the wire, the electricity can do work as it flows through the wire. In the picture above, electrons flow from the negative end of the battery through the wire to the light bulb. The electricity flows through the wire in the light bulb and back to the battery.

http://www.eia.doe.gov/kids/energyfacts/sources/electricity.html

ELECTRICITY TRAVELS IN CIRCUITSElectricity travels in closed loops, or circuits (from the word circle). It must have a complete path before the electrons can move. If a circuit is open, the electrons cannot flow. When we flip on a light switch, we close a circuit. The electricity flows from the electric wire through the light and back into the wire. When we flip the switch off, we open the circuit. No electricity flows to the light. When we turn a light switch on, electricity flows through a tiny wire in the bulb. The wire gets very hot. It makes the gas in the bulb glow. When the bulb burns out, the tiny wire has broken. The path through the bulb is gone. When we turn on the TV, electricity flows through wires inside the set, producing pictures and sound. Sometimes electricity runs motors—in washers or mixers. Electricity does a lot of work for us. We use it many times each day.

http://www.eia.doe.gov/kids/energyfacts/sources/electricity.html

ElectromagnetElectromagnets are usually in the form of iron core solenoids. The

ferromagnetic property of the iron core causes the internal magnetic domains of the iron to line up with the smaller driving

magnetic field produced by the current in the solenoid. The effect

is the multiplication of the magnetic field by factors of tens to even thousands. The solenoid field relationship is

and k is the relative permeability of the iron, shows the magnifying effect of the iron core.

http://media.fwbell.com/mag.html

How do I make an electromagnet?It is fairly easy to build an electromagnet. All you need to do is wrap some insulated copper wire around an iron core. If you attach a battery to the wire, an electric current will begin to flow and the iron core will become magnetized. When the battery is disconnected, the iron core will lose its magnetism. Follow these steps if you would like to build the electromagnet described in our Magnets and Electromagnets experiment:

Step 1 - Gather the Materials

To build the electromagnet described in our Magnets and Electromagnets experiment, you will need:

One iron nail fifteen centimeters (6 in) long

Three meters (10 ft) of 22 gauge insulated, stranded copper wire

One or more D-cell batteries

A pair of wire strippers

Step 2 - Remove some Insulation

Some of the copper wire needs to be exposed so that the battery can make a good electrical connection. Use a pair of wire strippers to remove a few centimeters of insulation from each end of the wire.

Step 3 - Wrap the Wire Around the Nail

Neatly wrap the wire around the nail. The more wire you wrap around the nail, the stronger your electromagnet will be. Make certain that you leave enough of the wire unwound so that you can attach the battery.

When you wrap the wire around the nail, make certain that you wrap the wire all in one direction. You need to do this because the direction of a magnet field depends on the direction of the electric current creating it. The

movement of electric charges creates a magnetic field. If you could see the magnetic field around a wire that has electricity flowing through it, it would look like a series of circles around the wire. If an electric current is flowing directly towards you, the magnetic field created by it circles around the wire in a counter-clockwise direction. If the direction of the electric current is reversed, the magnetic field reverses also and circles the wire in a clockwise direction. If you wrap some of the wire around the nail in one direction and some of the wire in the other direction, the magnetic fields from the different sections fight each other and cancel out, reducing the strength of your magnet.

Step 4 - Connect the Battery

Attach one end of the wire to the positive terminal of the battery and the other end of the wire to the negative terminal of the battery. If all has gone well, your electromagnet is now working!

Don't worry about which end of the wire you attach to the positive terminal of the battery and which one you attach to the negative terminal. Your magnet will work just as well either way. What will change is your magnet's polarity. One end of your magnet will be its north pole and the other end will be its south pole. Reversing the way the battery is connected will reverse the poles of your electromagnet.

Hints to Make Your Electromagnet Stronger

The more turns of wire your magnet has, the better. Keep in mind that the further the wire is from the core, the less effective it will be.

The more current that passes through the wire, the better. Caution! Too much current can be dangerous! As electricity passes through a wire, some energy is lost as heat. The more current that flows through a wire, the more heat is generated. If you double the current passing through a wire, the heat generated will increase 4 times! If you triple the current passing through a wire, the heat generated will increase 9 times! Things can quickly become too hot to handle.

Try experimenting with different cores. A thicker core might make a more powerful magnet. Just make certain that the material you choose can be magnetized. You can test your core with a permanent magnet. If a permanent magnet is not attracted to your core, it will not make a good electromagnet. An aluminum bar, for example, is not a good choice for your magnet's core.

Gravity

Gravity is a force that for us is always directed downwards. But to say that gravity acts downwards is not correct. Gravity acts down, no matter where you stand on the Earth. It is better to say that on Earth gravity pulls objects towards the centre of the Earth. So no matter where you are on Earth all objects fall to the groundSee the diagram:

What is gravity?Gravity is a force that attracts objects together. On earth this force attracts everything to Earth.

The strength of gravity.

The Earth is a very large object and it is also very heavy. This means that it has got a strong gravitational field.The moon is smaller than the Earth and is not as heavy.Would you expect its gravity to be stronger or weaker than the Earth's gravity?

Famous People & Electricity!Benjamin Franklin

Ben Franklin harnessed electricity by flying a kit with an iron key attached to

the string. Franklin was a curious man, and he experimented during thunderstorms until he invented

the lightning rod. He also invented bifocal glasses, and the Franklin stove. Benjamin Franklin signed the Declaration of Independence, and several other important

documents. Franklin was certainly a well-rounded man!

Michael FaradayThe Quarterly Journal of Science and the Arts (1818)

The son of an impoverished blacksmith, Faraday was apprenticed as a bookbinder. He read every book he bound. After securing menial work at the Royal Institution, Faraday went on to discover electromagnetic induction, the battery and the dynamo. He did pioneering work in electrochemistry, isolated benzene and produced aluminum by electrolysis. He built the first electric motor, and later the first generator and transformer.

Thomas EdisonThe inventor Thomas Alva Edison (in the USA) experimented with thousands of different filaments to find just the right materials to glow

well and be long-lasting. In 1879, Edison discovered that a carbon filament in an oxygen-

free bulb glowed but did not burn up for 40 hours. Edison eventually produced a bulb that could glow

for over 1500 hours.

STATIC ELECTRICITY

Electricity has been moving in the world forever. Lightning is a form of electricity. It is electrons moving from one cloud to another or jumping from a cloud to the ground. Have you ever felt a shock when you touched an object after walking across a carpet? A stream of electrons jumped to you from that object. This is called static electricity.

Have you ever made your hair stand straight up by rubbing a balloon on it? If so, you rubbed some electrons off the balloon. The electrons moved into your hair from the balloon. They tried to get far away from each other by moving to the ends of your hair.

They pushed against each other and made your hair move—they repelled each other. Just as opposite charges attract each other, like charges repel each other.

Static Electricity Experiment

Image right: Static electricity from a balloon really makes an empty soda can move! Credit: NASA

You will need: balloons empty soda can string (if you like)

Here's what you do:

1. Blow up the balloon.2. Rub the balloon on your head. This makes an electrical charge.3. Lay the soda can on a smooth floor.4. Bring the balloon close to the can.5. Look at what happens.6. Have a race with a friend with two cans and two balloons. See who can move the can across the room first, without touching it.7. Try rubbing the balloon on your hair and then sticking it to a wall.8. Tie string to the ends of two balloons that you have blown up.9. Rub the two balloons together.10. Hold them by the strings right next to each other.11. Watch what happens.

Lightning - The Great Mystery

In an electrical storm, the storm clouds are charged like giant capacitors in the sky. The upper portion of the cloud is positive and the lower portion is negative. How the cloud acquires this charge is

Image above: Static electricity makes your hair stand up Credit: NASA

Image above: Static electricity makes the can move Credit: NASA

Image above: Static electricity moves one balloon away from the otherCredit: NASA

still not agreed upon within the scientific community, but the following description provides one plausible explanation.

In the process of the water cycle, moisture can accumulate in the atmosphere. This accumulation is what we see as a cloud. Interestingly, clouds can contain millions upon millions of water droplets and ice suspended in the air. As the process of evaporation and condensation continues, these droplets encounter many collisions with other moisture that is in the process of condensing as it rises. Also, the rising moisture may collide with ice or sleet that is in the process of falling to the earth or located in the lower portion of the cloud. The importance of these collisions is that electrons are knocked off of the rising moisture, thus creating a charge separation.

The newly knocked-off electrons gather at the lower portion of the cloud, giving it a negative charge. The rising moisture that has just lost an electron carries a positive charge to the top of the cloud. Beyond the collisions, freezing plays an important role. As the rising moisture encounters colder temperatures in the upper cloud regions and begins to freeze, the

frozen portion becomes negatively charged and the unfrozen droplets become positively charged. At this point, rising air currents have the ability to remove

the positively charged droplets from the ice and carry them to the top of the cloud. The remaining

frozen portion would likely fall to the lower portion of the cloud or continue on to the ground. Combining

the collisions with the freezing, we can begin to understand how a cloud may acquire the extreme charge separation that is required for a lightning

stroke.

Series & Parallel

CircuitsThere are 2 ways to connect multiple devices to a power source (e.g. speakers to an amplifier), series and parallel. Well... OK, there's also series/parallel. But we'll cover that on a later section.

CapacitorsA capacitor is an electrical device that consists of two conductive surfaces separated by an insulating (dielectric) media. When a voltage is applied to the surfaces, energy is stored in the resulting electric field created by the charge separation of the surfaces.

You can create a simple capacitor by separating two sheets of aluminum foil with a sheet of plastic wrap. The quality of the capacitor is controlled by the size of the two pieces of foil, the insulating quality of the plastic and the thickness of the plastic -- the closer the two pieces of foil, the better the capacitor. A good, large capacitor can easily store enough electricity to melt a screwdriver!

A cloud acts like a huge capacitor. The top and bottom of the cloud are like the two pieces of foil. Huge amounts of electricity can be stored inside this cloud capacitor.

Speakers in series

In a series circuit (like the two above), the current must flow through one device to get to the next device. This means that the rate of current flow through all devices is the same. The voltage across each device depends on its impedance/resistance of each device and the current flowing through the circuit. When adding more components in a series circuit, the current flow decreases, if the applied voltage remains constant.

Example of Series Circuits : Christmas lights (when one goes out they all go out)

Speakers in parallel

In a parallel circuit (like the two examples above), each device is directly connected to the power source. This means that each device receives the same voltage. The amount of current flowing through each device is dependent on the impedance/resistance of that particular device. If devices are added to the power source in a parallel configuration, the current demand/flow from the power source increases.

Examples of Parallel Circuits: Computer (the electricity flows to each item in the computer to make it work)

http://www.bcae1.com/srsparll.htm