By creating a simple circuit, your students can explore the connection between electricity and magnetism. Compasses reveal the presence of invisible, magnetic fields around wires through which electricity flows.
Before beginning this activity, make sure that your students know a little bit about magnetism. The "Find the magnetic field" activity is a great introduction to the topic.
Each group will need:
Organize your students into small groups of three or four.
Have the groups talk with each other about electricity and magnetism. Ask each group to share a few ideas. Make sure that by the end of the conversation, your students understand that electricity and magnetism are closely related.
Note that the compasses can be placed under the wire in any orientation, but the wire needs to cut across the middle of the compass.
Remind the students to be safe when working with electricity, and have them follow the steps on their "Linking magnetism and electricity" worksheets:
Your students should be recording their observations and answering the questions on their worksheet. In their groups, have them review what they’ve learned about the relationship between electricity and magnetism.
Ask the groups to each share some observations about their circuits and the response of the compass needles. Were their predictions accurate?
Review the worksheet responses of your students.
Procedure and observations
A: No matter where the compass is placed, when it is under the wire and the circuit is closed, the compass needle will point across, or perpendicular to, the wire.
Analysis and conclusions
Q: How are your observations different from how you thought a compass works?
A: The compass needle moves from magnetic north to a position perpendicular to the wire.
This investigation shows that the compass needle is affected by the electricity moving through the circuit.
Why do you think the compass is responding to the electricity?
The compass needle moves in response to the electricity because a magnetic field is created in the wire when the circuit is connected.
What is the connection between a bar magnet and a wire with electricity owing through it?
They both have a magnetic field around them.
Ask your students to research the role of electromagnetism in the Aurora Borealis (Northern Lights). NASA has a number of videos that you can watch as a class.
Spotlight the work of scientist Hans Christian Oersted (1777–1851) who discovered the relationship between magnetism and electricity. In 1820, his experiments revealed that a magnetic field is created when electricity flows through a wire carrying current. That is exactly what your students are doing in this activity.
Compass needles react to magnetic fields. Normally, they align to Earth’s magnetic field, which is created by the movement of liquid metal in the core of the planet.
But compasses will also react to smaller magnetic fields, like those in an electric circuit.
When a circuit is closed, electrons move through the wire, creating an electrical current. The movement of the electrons through the metal of the wire produces a magnetic field around the wire. The compass needle reacts to this magnetic field.