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What is Electricity?

  • Introduction
  • Results & Video
  • Materials
  • Procedure
  • Preparation & References
  • Downloads

We see electricity in use every day, but do you know what it is? Electric current is created by the movement of charged particles. The particles that are moving in electric currents are electrons (e-). Electrons are relatively loosely held pieces of atoms. The atom is the smallest building block of matter. All atoms (picture right) have a very compact, very dense, core called the nucleus, which holds all the positively charged particles, called protons. The nucleus is even smaller relative to the space occupied by electrons than is illustrated here.

Protons cannot move out of the nucleus. When they do, this phenomenon is called a nuclear process. In metals, electrons can move freely along atoms of the metal. This movement is called electricity. Electrical wires are made of metals because they allow the electrons to flow. Interestingly, the direction of the current is opposite the direction of movement of the electrons. Electricity was discovered before the electron, so scientists described the movement of the positive charge, which turns out to reflect the absence or loss of an electron. As shown below, in an electric circuit, electrons flow in one direction along metal atoms. The direction of the current is described in the opposite direction.

ejump

Materials that can move electrons are said to be conductors. Materials that do not allow electrons to flow between atoms are called insulators. Nonmetallic materials tend to be insulators and metallic materials tend to be conductors. In this activity, students classify materials as conductors or insulators.

 

Video & Results

None at this time.

Materials

  • Testing circuit board

A selection of conducting materials:

  • aluminum foil
  • a penny or other coins
  • a metal spoon
  • cup of salt water

A selection of insulating materials:

  • paper
  • mouse pad
  • piece of wood
  • rubber band
  • cotton fabric
  • cup of distilled water

 

Procedure

circuit

What is a circuit?

  1. We are going to setup a circuit, an uninterrupted loop of materials that can conduct electricity with a battery to provide the electrical source.
  2. Pick a circuit board with a lamp installed.
  3. If there isn't already a battery in place, place a D battery between the screws on the top left corner.
  4. Use the wires with clips on the ends to connect the screw touching the "+" battery anode to a screw that is beneath the light bulb.
  5. Connect the other anode (-) of the battery with another clipped wire.
  6. Right now, the circuit is "Open", there is a break in the loop, so electricity cannot flow through the wires.
  7. Connect or touch the 2 free ends of the wires. If all is secured, the light bulb should glow. You have "Closed" the circuit , so electricity can flow through the wires and power the light. If it doesn't check that all important parts are touching.
  8. Unhook the wire clips so that the battery doesn't drain.

 

Go with the Flow?test

  1. Choose a material for testing. Do you expect it to conduct electricity? Why?
  2. Place the alligator clips from the circuit on each end of the material. Make sure that the clips do not touch each other.
  3. Does the light turn on? If so, it was a conductor! If not, it is an insulator.
  4. Test several materials and see if you can find some common features among the conductors and some common features among the insulators.

Preparation & Notes

Circuit Testing Board

We made the circuit board from 1 ft sections of 1x12 wood (purchased at Home Depot). We also purchased a variety pack of wood screws from Home Depot. ($15 for 4 circuit boards, not including the alligator clip leads purchased from Radio Shack)

D Battery Holder - For the 1.5 V D battery holder 1 1/2 " wood screws were secured to the board approximately 7 cm apart. One wood screw was precisely at the height of the protruding plus (+) electrode of the battery. The height of the other screw was less critical. A short 1/2" wood screw was secured to the board, lower to the wood as added support to hold the battery in place. The battery needs to fit tightly so that the current runs consistently.

Lamp Holder - There are a variety of bulbs that can be used, that are available from Radio Shack. We found that re-purposing the light bulb in its holder from a small flashlight (not an led light) worked well. The reflective cone made the lamp appear brighter and it was easier to fix screws to the board that would hold it in place. We put one short screw underneath the bottom terminal. The lamp sat on top of this screw and an alligator clip was attached to it. Taller screws were secured to hold the bulb in place and to connect the side terminal of the housing.

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