The north pole of a bar magnet points towards a thin circular coil of wire containing 40 turns. The magnet is moved away from the coil, so that the ux through one turn inside the coil decreases by ∆Φ = 0.3 T. m2 in a time ∆t = 0.2 s. What is the average EMF induced in the (whole) coil during this time interval? Viewed from the side opposite of the bar magnet (from the right), does the induced current run clockwise or counterclockwise? Explain briey. [2 p.]

60 V

The direction will be anticlockwise from the right side of the magnet.

Explanation:

The change in magnetic flux = ∆Φ = 0.3 T.m^2

The change in time = ∆t = 0.2 s

number of turns = 40 turns

The induced emf E = N∆Φ/∆t =

E = (40 x 0.3)/0.2 = 60 V

If the magnet is moved away from the coil, the induced current on the coil will try to oppose the motion of the magnet by attracting the magnet towards the coil. For the magnet to be attracted towards the coil, it must possess the equivalent of a magnetic south pole. For the equivalent of a magnetic south pole, the current on the coil will flow in the clockwise direction when viewed from the left side of the magnet. When viewed from the right side of the magnet, the direction will appear as anticlockwise.