Question

A flashlight can be made that is powered by the induced current from a magnet moving through a coil of wire. The coil and magnet are inside a plastic tube that can be shaken causing the magnet to move back and forth through the coil. Assume the magnet has a maximum field strength of 0.05 T. Assume that the radius of the coil is 1.5 cm and the magnet is shaken with a frequency of about two shakes (each back and forth) per second. Specify the the number of turns necessary to light a standard 1-Watt, 3-V flashlight bulb.

Express your answer using two significant figures.

N =

1.1×104

turns

In the studio, you built a working flashlight using a coil of copper that was 200 feet in length, with diameter of approximately 2.0 cm. How many turns did your coil have?

Express your answer using two significant figures.

???

Answer 1