Which description best describes a magnet (bar)?

• A. A device powered by electricity to maintain a field
• B. Fixed; strength and polarity can't change; persistent
• C. A temporary magnet that loses magnetism quickly
• D. Variable strength depending on position

Answer: (B)

A bar magnet is a permanent magnet. It has fixed magnetic polarity (north and south) and maintains its magnetization without any power source. That persistence—magnetism that stays over time unless heated, damaged, or exposed to a strong opposing field—best describes what a bar magnet is.

The other ideas describe things that aren’t a bar magnet: something powered by electricity to produce a field is an electromagnet, a magnet that loses magnetism quickly is a temporary magnet, and while the field indeed weakens with distance, that doesn’t define the bar magnet’s essential nature as a permanent, unpowered magnet.