Question

4.2.4 quiz: electromagnetism
question 3 of 10
what must be done to the wires used to make an electromagnet before they are connected?
a. the wires must be rubbed with sandpaper to make their surfaces rough.
b. the insulation must be removed from the ends of the wires.
c. the terminals of the battery must be coated with an insulating material.
d. the ends must be marked to show which end to attach to each terminal of the battery.

Explanation:

To make an electromagnet, wires are usually insulated. For the circuit to be complete (so that current can flow through the wire around the core of the electromagnet and create a magnetic field), the insulation at the ends of the wires (where they will be connected to the battery terminals) must be removed. Rubbing with sandpaper to make the surface rough (Option A) is not relevant for electrical connection. Coating battery terminals with insulating material (Option C) would prevent current flow. Marking the ends (Option D) is not a necessary step - the main requirement is a conductive connection, which is achieved by removing insulation.

Answer:

B. The insulation must be removed from the ends of the wires.