Answers to Faraday’s Law of Magnetic Induction – The Generator

Prepare

The Hoover Dam uses the power of the Colorado River to generate electricity. In this simulation, you will investigate this phenomenon and identify how changing properties of the generator will alter the amount of electrical energy derived from the dam.

First, open the simulation using the link found in Module 6.

Investigate:

Part 1. The Pickup Coil.

Click on the Pickup Coil tab. The simulation window shows a bar magnet and a light bulb connected to a loop of wire. Note that there is no battery in this setup. The arrows dispersed throughout the simulation indicate the direction of the magnetic field at each point in the scene.

  1. Move the magnet around the scene. Describe what happens to the electrons and the bulb as you do this.
  2. The electrons move around the coil when the magnet is moved around the scene, but do not move around the coil when the magnet is stationary.
  3. Move the magnet to the center of the coil and leave it stationary. Describe the light bulb and the electrons in the wire.
  4. As the magnet is moved towards the center of the coil, the electrons move in the coil and when the magnet comes to rest, the electrons stop moving.
  5. Starting with the magnet in the center of the coil, slowly pull the magnet out of the coil. Describe what happens to the bulb.
  6. The electrons in the wire on top of the magnet move slowly upward, causing a clockwise current in the coil when viewed from the right. This current produces a light in the bulb.
  7. What can you do in this simulation to make the light bulb glow brighter?
  8. You can either increase the strength of the bar magnet, move the magnet faster away from the coil, increase the loop area, increase the number of loops, or a combination of any of these changes.
  9. What should you do with the magnet to keep the light bulb on?
  10. The only way to keep the bulb lit is to oscillate the magnet through or near the coil.
  11. What have you learned about the effects of a magnetic field and how it creates a current in the loop of wire?
  12. A moving magnet, which produces a changing magnetic field in the center of the loop, creates a current in a loop of wire.

Part 2. The Generator

Click on the Generator tab. The simulation window shows a faucet of water. You can turn on the faucet by sliding the control bar on the spigot. Again, note that there is no battery in this setup.

  1. Turn on the faucet and record what happens as more water comes out of the tap.
  2. List three ways you can increase the brightness of the bulb in this simulation.
  3. Increase the amount of water coming out of the faucet,
  4. Increase the strength of the magnet,
  5. Increase the number of loops or the loop area,
  6. Or a combination of any of the above.
  7. Switch the bulb to the meter. This meter shows the current direction in the loop of wire and repeat step 2 above. Does this change any of your answers?

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Evaluate:

Explain Faraday’s law in your own words and describe how the flashlight in the picture below works.

The shaking of the flashlight moves a magnet that can pass through a copper loop of wire, pictured in the photo. The motion of the magnet creates a changing magnetic field in the wire which causes electrons in the wire to oscillate. This oscillation provides the current in the flashbulb to turn on the light. Most likely, the loop of wire is also hooked up to a battery which will provide some current in the circuit for a limited amount of time after the shaking stops.