Question

A square coil ABCD is placed in an x-y plane with its centre as the origin. A long straight wire passing through origin carries a current in negative z-direction. Current in this wire increases with time. The induced current in the coil is:

A. Clockwise
B. Anticlockwise
C. Zero
D. alternating

Answer 1

To predict the direction of the induced current in the coil, we need to refer accordingly with Lenz law of Electromagnetic induction which states that the induced electromotive force with different polarities induces a current whose magnetic field opposes the change in magnetic flux through the loop in order to ensure that original flux is maintained through the loop when current flows in it.

Complete step-by-step answer:
The information given to us:
A long straight wire passing through origin carries a current in negative z-direction and Current in this wire increases with time, that is the magnetic flux linked to the coil changes and increases with time.
In accordance with the Lenz law, the resultant induced electromotive force would induce a current in the loop whose magnetic field would tend to oppose the change in the magnetic flux i.e. increment in the magnetic flux, thus consequently trying to reduce it by inducing a resultant current whose magnetic field is in the opposite direction to the one in the initial phase that is
Magnetic field of the resultant induced current will be out of the plane and subsequently the direction of the resultant induced current will be anti-clockwise.
Therefore the correct option will be (B) anticlockwise

So, the correct answer is “Option (B)”.

Note: One is advised to note and remember that Lenz’s law depends on the principle of conservation of energy and Newton’s third law and is the most convenient method to determine the direction of resultant induced current.