Question

There is a coil in a plane of a page that contains 25 turns (loops). The diameter of the coil is 9.00cm and its resistance is 5.0Ω. The coil is in a uniform magnetic field directed out of the page. At t = 0, the magnitude of the field is 0.200T. The strength of the field is increased at a constant rate for 10.0s until it reaches 2.20 T. It is held constant at that value for 9.00s. Then it is decreased at a constant rate for 15.0s until it reaches zero.

1) Find the induced current in the coil at (i) t = 9.00 s, (ii) t = 15.0 s, (iii) t = 20.0 s?

2) At each of the times listed in the first part, if the magnitude of the current is non-zero, determine the direction of the current. (Apply to Lenz’s law.)

Answer 1

2) For first case induced current is clockwise

For second case there is. No induced current.

Inn third case innduced current is anticlockwise.

This is due to lenz law. Current is induced such that it opposes flux change , so first see if flux is increasing or decreasing, if it is increasing than induced magnetic field will be in opposite direction and decreasing flux it is in the direction of magnetic field. So by the direction of induced magnetic field check the induced current direction.