Question

A student is designing an electromagnet to lift heavier metal washers for a classroom engineering challenge. The current power source remains available, but the student wants to maximize the magnetic field strength of the electromagnet without changing the battery.

Which modification would most effectively increase the strength of the electromagnet?






(3 points)

Decrease the voltage supplied to the coil to prevent overheating

Replace the iron core with a plastic rod of the same size

Add more coils of wire around the iron core and increase the current flowing through the wire

Use a longer, thinner wire to increase resistance in the circuit
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Answer 1

"Add more coils of wire around the iron core and increase the current flowing through the wire."

Reason: The magnetic field of a solenoid is roughly proportional to N·I (number of turns times current) and is greatly amplified by a ferromagnetic iron core. The other choices either reduce current (lower voltage or higher resistance) or remove the high‑permeability core (plastic), all of which weaken the field. (Be mindful of battery/current limits and overheating when increasing current.)