Question

Lisa made the electromagnet shown.

A nail with wire coiled around it has its head labeled S to the right and its point labeled N to the left. The end of the wire leading to the S is attached to the positive terminal of a battery. The end of the wire leading to the N is attached to the negative terminal of the battery.

What can Lisa do to increase the strength of the electromagnet?

She can use a nail with weaker magnetic properties.
She can change the direction of the nail.
She can increase the number of wire loops.

Answer 1

Only the third statement is correct: increasing the number of wire loops will increase the electromagnet’s strength.

Brief explanations:
- Using a nail with weaker magnetic properties would make it weaker, not stronger.
- Changing the nail’s direction only reverses the poles (north/south), it doesn’t increase the field magnitude.
- More turns (and/or more current or a core with stronger magnetic properties) increases the magnetic field (B ∝ N·I for a coil).