Question

what could be done to make the lamp brighter?
a. turn the coil slower
b. turn the coil faster
c. decrease the size of the magnets
d. change the polarity of the magnets

Explanation:

The brightness of the lamp in an electromagnetic - induction based setup depends on the induced electromotive force (EMF). According to Faraday's law of electromagnetic induction, the induced EMF is proportional to the rate of change of magnetic flux. Turning the coil faster increases the rate of change of magnetic flux through the coil, which in turn increases the induced EMF and the current in the circuit, making the lamp brighter. Turning the coil slower decreases the induced EMF. Decreasing the size of the magnets reduces the magnetic field strength and thus the induced EMF. Changing the polarity of the magnets does not affect the magnitude of the induced EMF but only its direction.

Answer:

B. turn the coil faster