Question

A magnet, when moved near a coil, produces an induced potential difference in the coil, What happens when we increase the speed of the magnet near the coil?

• A. The induced current in the coil remains the same.
• B. The induced potential difference remains the same.
• C. The induced potential difference in the coil decreases.
• D. The induced potential difference in the coil increases.

Answer 1

Answer:

D. The induced potential difference in the coil increases.

• When the speed of the magnet near the coil increases, the rate of change of magnetic flux through the coil increases.

• According to Faraday's law of electromagnetic induction, the magnitude of the induced electro motive force (EMF) is directly proportional to the rate of change of magnetic flux.

• As the falling height of the magnet through a coil increases, the speed of the magnet increases, which in turn increases the rate of change of magnetic flux through the coil, and hence increases the induced EMF and current according to Faraday's Law and Lenz's Law.

• Therefore, increasing the speed of the magnet increases the induced potential difference in the coil