Juan makes an adjustment to an electromagnet that causes the electromagnet to lose some of its strength. What did Juan most likely do? He reduced the number of loops in the wire. He increased the number of loops in the wire. He reduced the length of the wire. He increased the length of the wire.
The correct answer and explanation is:
The correct answer is: He reduced the number of loops in the wire.
Explanation:
An electromagnet’s strength depends mainly on three factors:
- Number of loops (coils) of wire around the iron core
- Amount of current flowing through the wire
- Core material (usually iron, which enhances magnetism)
When Juan makes an adjustment that causes the electromagnet to lose strength, the most likely cause is that he reduced the number of loops of wire.
Here’s why:
- Number of loops: The magnetic field produced by an electromagnet is directly proportional to the number of loops of wire. Each loop contributes to the total magnetic field, and more loops mean the magnetic fields from each coil add together, strengthening the overall magnet. Reducing the number of loops decreases the total magnetic field, weakening the electromagnet.
- Increasing the number of loops would do the opposite—it would increase the magnet’s strength by adding more coils.
- Length of the wire: The length of the wire itself doesn’t directly determine the magnet’s strength. However, if the wire length is increased or decreased by adding or removing loops, it affects the number of loops, which affects strength. Simply changing the wire length without changing loops or current doesn’t have a straightforward effect.
- Electric current: The strength also depends on the current. If Juan reduced the current, the magnet would weaken. But the question focuses on the number of loops or wire length, so current changes are not the main focus here.
In summary, because the magnetic field strength depends directly on the number of wire loops wrapped around the core, reducing the number of loops decreases the strength of the electromagnet. This is the most straightforward explanation for Juan’s observation.