Key learning points

1. When there is an electric current in a wire, there is a magnetic field around the wire.
2. An electromagnet is a magnet that can be turned on with an electric current, and turned off.
3. The magnetic field of an electromagnet is similar to the field around a bar magnet.
4. A soft iron core in an electromagnet becomes magnetised and adds to the strength of field when the electromagnet is on.
5. When there is an electric current in a coil of wire, the magnetic field around each loop adds to make a stronger field.

Keywords

• Coil of an electromagnet - is an insulated wire wound into the shape of a spring.

• Turn of wire - is a single loop of wire in a coil.

• Soft iron - is very pure iron that cannot be made into a permanent magnet.

• Directly proportional to - describes the relationship between two variables, in which doubling the value of one variable doubles the value of the other.

• Error bars - show the accuracy of each measurement on a graph.

Common misconception