Key learning points

1. A soft iron core increases the strength of an electromagnet because it becomes magnetised when it is turned on.
2. The more tightly wound the coil of wire is in an electromagnet, the stronger its magnetic field.
3. The greater the current through the coil of an electromagnet, the stronger its magnetic field.
4. The strength of an electromagnet is directly proportional to the current through it.

Common misconception

Keywords

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

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

• Soft iron - 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 - These show the accuracy of each measurement on a graph.