Question

Pedro uses a bar magnet to pick up a nail. He then touches the tip of the nail to some staples.

Why do some of the staples stick to the nail?

The nail and the bar magnet are now both permanent magnets.
The nail has become a temporary magnet, while the bar magnet remains a permanent magnet.
The nail has become a permanent magnet, while the bar magnet has become a temporary magnet.
The nail and the bar magnet are now both temporary magnets.

Answer 1

The nail has become a temporary magnet, while the bar magnet remains a permanent magnet.

Explanation: The bar magnet induces alignment of the nail’s magnetic domains, so the nail becomes magnetized and can pick up staples. Because typical nails are soft iron, this induced magnetism is temporary (it disappears when the inducing field is removed), whereas the bar magnet is a permanent magnet.