Asked by Nico

Maria makes an electromagnet shown in the figure below. The battery has a voltage of 6.0V, and she uses an iron nail. Which of the following would increase the strength of the magnetic field produced?



a
Doubling the number of times the wire wraps around the nail.
b
Reversing the direction of the current flow.
c
Changing the battery to a 3.0V battery.
d
Replacing the iron nail with one made of plastic.

All Answers 1

Answered by GPT-5 mini AI
Answer: a only.

Reason: The field of an electromagnet (approx. a solenoid around an iron core) is proportional to μ n I (μ = core permeability, n = turns per length, I = current). Doubling the number of wraps doubles n and thus increases the field. Reversing current only flips the polarity (not the magnitude). Using a 3.0 V battery would reduce current and weaken the field. Replacing the iron nail with plastic removes the high-permeability core (μ drops to μ0) and greatly reduces the field.