Question

A conducting loop held below a current-carrying wire PQ as shown. Predict the direction of the induced current in the loop when the current in the wire is constantly increasing.

Answer 1

Hint: The magnetic field produced by the current-carrying wire PQ will be towards the plane of the circular wire and the magnetic field is increasing. The induced current in the circular loop will oppose this increase in the magnetic field by having an induced current in the anticlockwise direction.

Complete answer:
We know that the direction of the magnetic field that is produced by a straight current-carrying wire is given by the right-hand thumb rule. If you place the thumb of your right hand in the direction of the current, then the direction of the magnetic field produced by that current-carrying wire will be in the direction that your fingers point to.
So, here the magnetic field produced by the current-carrying wire PQ will be towards the plane of the circular wire as shown in the following diagram

Here the current in the current-carrying wire is increasing so the magnetic field linking with the circular loop will also increase.
The direction of the magnetic field that a circular loop produces is also decided by the right-hand thumb rule, but in this case, the direction of flow of current in the circular loop is represented by the curl of the fingers of the right hand and the direction of the magnetic field is represented by the thumb.
Now we also know that the direction of the electric current induced by a changing magnetic field in a circular circuit is such that the induced current produces a magnetic field that opposes the changing magnetic field.
In simpler terms, let’s consider the problem given to us. Here the magnetic field produced by the current-carrying PQ is towards the plane of circular loop and is constantly increasing, so the induced current in the circular loop will oppose this increase in the magnetic field by having an induced current in the anticlockwise direction.
The direction of the induced current in the conducting circular loop is anticlockwise.

Note:
The concept of induced current that we used to solve the problem given to us, is the basis of AC generator which uses the energy for a source (water, air, etc.) to rotate a conducting loop which is placed in a constant magnetic field, which will be used to produce an AC in an AC generator.