Electricity is carried by current, or the flow of electrons. One useful characteristic of current is that it creates its own magnetic field. This is useful in many types of motors and appliances. Conduct this simple electromagnetic induction experiment to witness this phenomenon for yourself!
Observe how current can create a magnetic field.
What will happen when the battery is connected and the switch is turned on? Will the battery voltage make a difference in the magnetic field?
- Thin copper wire
- Long metal nail
- 12-V lantern battery
- 9-V battery
- Wire cutters
- Toggle switch
- Electrical tape
- Paper clips
- Cut a long length of wire and attached one end to the positive output of the toggle switch.
- Twist the wire at least 50 times around the nail to create a solenoid.
- Once the wire has covered the nail, tape the wire to the negative terminal of the 12V battery.
- Cut a short piece of wire to connect the positive terminal of the battery to the negative terminal of the toggle switch.
- Turn on the switch.
- Bring paper clips close to the nail. What happens? How many paper clips can you pick up?
- Repeat the experiment with the 9V battery.
- Repeat the experiment with the 9V and 12V batteries arranged in series (if you don’t know how to arrange batteries in series, check out this project that explains how).
The current running through the circuit will cause the nail to be magnetic and attract paper clips. The 12V battery will create a stronger magnet than the 9V battery. The series circuit will create a stronger magnet than the individual batteries did.
Electric currents always produce their own magnetic fields. This phenomenon is represented by the right-hand-rule:
If you make the “Thumbs-Up” sign with your hand like this:
The current will flow in the direction the thumb is pointing, and the magnetic field direction will be described by the direction of the fingers. This means when you change the direction of the current, you also change the direction of the magnetic field. Current flows (which means electrons flow) from the negative end of a battery through the wire to the positive end of the battery, which can help you determine what the direction of the magnetic field will be.
When the toggle switch is turned on, the current will flow from the negative terminal of the battery around the circuit to the positive terminal. When the current passes through the nail it induces, or creates, a magnetic field. The 12V battery produces a larger voltage; therefore, produces a higher current for a circuit of the same resistance. Larger currents will induce larger (and stronger!) magnetic fields, so the nail will attract more paperclips when using a larger voltage.