Question

4.3.2 test (cst): electromagnets
question 13 of 20
an electromagnet needs a magnetic metal core. to produce a magnetic field, what else is required?
a. a solenoid with no current running through it
b. a second metal core
c. a permanent magnet
d. a solenoid with current running through it

Explanation:

An electromagnet consists of a magnetic metal core and a solenoid (a coil of wire). When an electric current runs through the solenoid, it generates a magnetic field. Without current (as in option A), there is no magnetic field. A second metal core (option B) or a permanent magnet (option C) is not what's needed to produce the magnetic field in the context of an electromagnet's basic requirements. The key is the solenoid with current (option D) to create the magnetic field around the core.

Answer:

D. A solenoid with current running through it