Which description best describes an electromagnet?

Which description best describes an electromagnet?

• A. A device with a fixed non-adjustable field
• B. A device whose magnetic field cannot be changed
• C. Adjustable; electric current can be changed; not persistent
• D. A permanent magnet that relies on remanence

Answer: (C)

An electromagnet generates its magnetic field from electric current flowing through a coil around a magnetic core. The key idea is that the field strength is adjustable: increase the current or add more turns to strengthen the field, or reduce current to weaken it. The field exists only while current is flowing, so it is not persistent once the current is removed. This contrasts with a permanent magnet, which relies on remanent magnetization to stay magnetic after any external influence is gone.

An electromagnet generates its magnetic field from electric current flowing through a coil around a magnetic core. The key idea is that the field strength is adjustable: increase the current or add more turns to strengthen the field, or reduce current to weaken it. The field exists only while current is flowing, so it is not persistent once the current is removed. This contrasts with a permanent magnet, which relies on remanent magnetization to stay magnetic after any external influence is gone.