What is an electromagnet?

What is an electromagnet?

• A. A device that stores electrical energy as magnetic field
• B. A permanent magnet that requires no current
• C. An iron core made into a magnet by the passage of electric current through a coil surrounding it
• D. A conductor that carries current without any magnetic field

Answer: (C)

An electromagnet works by turning electric current into a magnetic field. When current flows through a coil of wire, it creates a magnetic field around the coil. Placing an iron core inside the coil concentrates and strengthens that field, so the core itself becomes magnetized while the current is on. When the current is turned off, the magnetic field vanishes. This matches the description of an iron core made into a magnet by the passage of electric current through a coil surrounding it. The other statements aren’t how electromagnets are defined: storing energy in a magnetic field describes energy storage in devices like inductors, a permanent magnet doesn’t need current, and a conductor with current certainly produces a magnetic field.

An electromagnet works by turning electric current into a magnetic field. When current flows through a coil of wire, it creates a magnetic field around the coil. Placing an iron core inside the coil concentrates and strengthens that field, so the core itself becomes magnetized while the current is on. When the current is turned off, the magnetic field vanishes.

This matches the description of an iron core made into a magnet by the passage of electric current through a coil surrounding it. The other statements aren’t how electromagnets are defined: storing energy in a magnetic field describes energy storage in devices like inductors, a permanent magnet doesn’t need current, and a conductor with current certainly produces a magnetic field.