Background:

In 1831, Michael Faraday made a significant discovery - that electric current could be generated in a coil of conducting wire if a magnet is moved through the coil.

In other words, the energy of motion of the magnet can be converted to electrical energy. This discovery paved the way for practical large-scale generation of electric current.

The Question:

Can electric current be generated with a coil of wire and a magnet?

Variables:

Identify the type of data you will collect to support your hypothesis and state the manipulated, responding and controlled variables in this investigation.

Materials:

• voltage sensor and alligator clips
• USB link
• computer
• bar magnet
• wire coil on RLC (or similar) circuit board - if not available, a wire coil can be constructed with the following:
• toilet paper tube
• about 4 m of thin gauge copper wire
• sandpaper
• tape

Procedure:

Step 1:

Obtain a voltage sensor and USB link, they look similar to the picture below:

Step 2:

Plug the sensor into the USB link (that is connected to the computer) and set up the computer to collect voltage data on a graph display. For example, if you are using DataStudio, your display should look something like this:

Step 3:

Attach the two alligator clip leads of the voltage sensor to the wire ends of the coil on RLC circuit board:

If you do not have a circuit board coil, construct a coil with the following steps:

• wrap the length of copper wire around the tube - make sure there is about 10 cm of wire left sticking out on each end of the coil.
• make sure the wire is squeezed tightly together on the tube, then secure it in position on the tube with the tape. If the wire is insulated, remove the insulation from about 1 cm of the ends with the sandpaper.

Step 4:

You are now going to drop the bar magnet through the coil. Orient the coil vertically do you can drop the magnet through it, and put something soft underneath the tube so the magnet will not dent countertops or floors.

*Note - magnets and computers do not mix! Keep the magnet away from the computer.

Step 5:

Start recording data. Place the magnet just inside the coil, then drop it through. Stop recording data. Click the appropriate button on the graph to properly scale the date (in DataStudio it is the autoscale button in the top left corner).

Analyzing and Interpreting:

Step 6:

Select the voltage data in your graph. Use the "smart cursor" in the DataStudio software to pinpoint the peak voltage produced when the magnet went through the coil (this may be a positive or negative value - it does not matter):

What was the peak voltage produced? Can electric current be generated with a coil of wire and a magnet? What energy conversion took place in this experiment?

Step 7:

How can different voltages be produced by an electromagnetic coil? To answer this question, try the following:

Repeat steps 6 and 7 several times, each time dropping the magnet through at a higher speed (the higher the speed, the greater the kinetic energy of the magnet). Make sure you drop the same end through first every time. The different speeds can be accomplished by dropping the magnet from greater and greater heights (you may require some practice to do this!). If you have tubes of different lengths (perhaps made from old tubes from wrapping paper), they can help to guide the magnet through the coil.

Make note of the peak voltages for all your trials.

Forming Conclusions:

Based on the data you have collected, write summary statements for the following questions:

1.	Can electric current be generated with a coil of wire and a magnet?
2.	What is the relationship between the kinetic energy of the magnet as it passes through the coil and the amount of voltage generated?

Extending:

Design and conduct experiments to find answers to the following questions:

• Will a coil generate voltage if a magnet is held inside the coil without moving?
• How does the strength of the magnet affect the amount of voltage generated?
• Is the voltage generated any different if the magnet is dropped through with a different pole (North or South) leading the way through the coil?