Which factors determine the strength of an electromagnet?

• A. The number of windings of a wire around a metal core.
• B. The type of metal core.
• C. The amount of current passing through the wire.
• D. All of the above.

Answer: (D)

The strength of an electromagnet comes from ampere-turns and the path the magnetic field can take. The magnetic field inside a coil is basically proportional to the number of turns times the current. More turns add up the magnetic effect, and more current increases it directly. The core material matters because a metal with high magnetic permeability concentrates the flux and lowers reluctance, making the field stronger; different cores also saturate at different levels, limiting how strong you can go. Because each factor—more windings, higher current, and a better core—can boost the magnetic field, all of these aspects contribute.