Circuit Experiment
As a boy, Thomas Edison built a small laboratory in his cellar. His early experiments helped develop a very inquisitive mind. His whole life was spent thinking about how things work and dreaming up new inventions. The light bulb and movie projector are just two of dozens of inventions.
You can build a very basic electrical circuit similar to what Edison may have crafted as a boy. And you can find out what happens when a current is "open" compared with when it's "closed."
Here's What You need:
1. Penlight bulb
2. Flashlight battery
3. Two 6" pieces of insulated wire (any kind will work)
4. Tape to keep the wire on the end of the battery
5. A small piece of thin flat metal to make a "switch"
6. Small block of wood
An Electrical Circuit
(From humorist Dave Barry's book Dave Barry in Cyberspace)
"Electricity is supplied by the wall socket, which is in turn connected to the electrical company via big overhead wires with squirrels running on them.
"A question many people ask ... is, 'How come the squirrels don't get electrocuted?' To answer that question, we need to understand exactly what an electrical circuit is.
"When you turn on a switch, electricity flows through the wire into the appliance, where it is converted via a process called electrolysis into tiny microwaves. These fly around inside the oven area until they locate the Hungry Hombre Heat 'n' Eat Hearty Burrito entree; they then signal the location to each other by slapping their tails in a distinctive pattern. The workers, or drones, then ... swarm around the queen; this causes the rapid warming that makes the entree edible and leads via amino acids, to digestion.
"This is followed by grunting and flushing, with the outflow traveling via underground pipes to the sewage treatment plant, which in turn releases purified water into the river, where it is used to form waterfalls, which rotate the giant turbines that produce the electricity that flows through wires back to your appliance, thereby completing the circuit.
"So we see that squirrels have nothing whatsoever to do with it. There is no need for you to worry about squirrels; believe me, they are not worrying about you."
Please Note: THIS IS A JOKE!!!
Here's What to Do
1. To make a switch:
* Take the block of wood and stick one thumb tack in
* Push the other thumbtack through the thin piece of flat metal.
* Push the thumb tack into the wood so that the piece of metal can touch the other thumb tack (see picture)
2. Connect the first piece of wire to a thumbtack on the switch.
3. Place the light bulb in the center of this wire piece.
4. Tape the end of the first piece of wire to one end of the battery.
5. Tape your second piece of wire to the opposite end of the battery.
6. Attach the end of your second piece of wire to the remaining thumbtack on the switch.
You've created an electrical circuit.
When you press the switch connecting the two thumbtacks, your circuit is "closed" and your current flows -- turning your light bulb on. When your switch is up, your circuit is "open" and your current can not flow -- turning your light bulb off, just like Thomas Edison's may have done.
The number of electrons we are willing to let across the circuit at one time is called "current". We measure current using amperes, or "Amps".
One AMP is defined as 6,250,000,000,000,000,000 (6.25 x 1018) electrons moving across your circuit every second!
Since no one wants to remember such a big number, that big number is called a "coulomb," after the scientist Charles A Coulomb who helped discover what a current of electricity is.
The amount of charge between the sides of the circuit is called "voltage." We measure Voltage in Volts. The word volt is named after another scientist, Alexader Volta, who built the world's first battery.
You'll remember that back in Chapter 1, we defined energy as the "ability to do work."
Well, one volt is defined as the amount of electrical charge needed to make one Coulomb (625,000,000,000,000,000,000 electrons) do one a specific amount of work -- which is labeled one joule.
Joule is also named after a scientist, James Prescott Joule. Do you remember him from Chapter 2?
Voltage, Current and Resistance are very important to circuits. If either voltage or current is too big you could break the circuit. But if either is too small, the circuit will not be able to work enough to be useful to us. In the same way, if the resistance is too big none of the electrons would be able to get though at all, but if it were too small, they would rush though all at once breaking the circuit on their way.
