Inside a motor, 30.0 A passes through a 250-turn circular loop that is 10.0 cm in radius. What is the magnetic field strength created at its center?

Video Transcript

This is College Physics Answers with Shaun Dychko. A circular loop with 250 turns of wire in the loop has a current of 30.0 amps running through it and a radius of 10.0 centimeters, which is 10.0 times 10 to the minus 2 meters and the question is what is the magnetic field strength in the center of the loop? And the formula for that is permeability of free space multiplied by current divided by 2 times the radius of the loop and that's for a single turn of wire and then we multiply that by the number of turns of wire, which is 250. So it works out to 250 times 4π times 10 to the minus 7 tesla meters per amp times 30.0 amps divided by 2 times 10.0 times 10 to the minus 2 meters, this is 0.0471 tesla.