Predict the direction of induced current in the situations described by the following Figs. 6.18(a) to (f).

Question

Philoid · Accepted Answer

The direction of induced current will be given by Lenz’s law.

According to the Lenz’s law: The direction of induced current by change in magnetic field (Faraday’s induction) will be such that it opposes the change that caused it.
As seen from the given figures, the direction of the induced current is shown when the north pole of the magnet is moved towards the closed loop or away from the closed loop.

	The direction of induced current will be along qrpq. Explanation: The magnetic field is given from “q” ⇒ “p”. ∴ the direction of induced current should be such that it should create a magnetic field which opposes the applied magnetic field. And to oppose the applied magnetic field, the current should flow counter - clockwise in the loop i.e. the direction of induced current will be “qrpq”
	The direction of induced current will be along prqp. Explanation: The magnetic field is given from “q” ⇒ “p”. ∴ the direction of induced current should be such that it should create a magnetic field (B_in as shown in the figure) which opposes the applied magnetic field. And to oppose the applied magnetic field, the current should flow counter - clockwise in the loop i.e. the direction of induced current will be “prqp”
	The direction of induced current will be along yzxy. Explanation: ∵ The current is flowing in the given loop in a clockwise, the direction of magnetic field will be as shown in the figure. ∴ the direction of induced current should be such that it should create a magnetic field (B_in as shown in the figure) which opposes the applied magnetic field. And to oppose the applied magnetic field, the current should flow counter - clockwise in the loop i.e. the direction of induced current will be “yzxy”
	The direction of induced current in will be along zyxz. Explanation: ∵ The current is flowing in the given loop in a counter - clockwise, the direction of field will be as shown in the figure. ∴ the direction of induced current should be such that it should create a magnetic field (B_in as shown in the figure) which opposes the applied magnetic field. And to oppose the applied magnetic field, the current should flow clockwise in the loop i.e. the direction of induced current will be “zyxz”
	The direction of induced current in the closed loop given in figure (e) after applying Lenz’s law will be along xryx. Explanation: ∵ The current is flowing in the given loop in a clockwise, the direction will be as shown in the diagram. But the tap key is released, means the magnetic field due to this current will decrease. ∴ the direction of induced current should be such that it opposes the decrease of magnetic field. Thus, the current will flow in clockwise direction to increase the magnetic field.
	There will be no current induced in the figure given in the figure (f) because the magnetic field lines are lying along the plane of the loop. Therefore, no current will be induced and hence no direction of induced current.