Question

Two electromagnets are made with the same core and the same type of wire. Electromagnet A has a low-intensity current, and electromagnet B has a high-intensity current. Which statement about the electromagnets is correct?
A. If they have the same number of turns in the wire, then they must have the same strength magnetic force.
B. If they produce the same strength magnetic force, then electromagnet A has more turns in the wire.
C. If they have the same number of turns in the wire, then electromagnet A has a stronger magnetic force.
D. If they produce the same strength magnetic force, then they must have the same number of turns in the wire.

Answer 1

B.

Magnetic strength (magnetomotive force) is proportional to the product N·I (number of turns × current). If A has a lower current but produces the same magnetic force as B, A must have a larger N (more turns).