Question

What is the direction of the induced current in the wire shown in the picture?

A. clockwise
B. counterclockwise

 

Answer 1

Concepts and reason

The concepts used to solve this problem are Lenz law and Maxwell’s right-hand thumb rule.

Use the Lenz law and right-hand thumb rule to find the direction of the induced current for the wire given in the diagram.

Fundamentals

Lenz law states that,

The direction of the induced current always opposes the change in the wire or the magnetic field that produces it.

Maxwell’s right-hand thumb rule states,

“If u hold a current-carrying wire in your right hand so that the thumb points in the direction of the current, then the direction in which fingers encircle the wire give the direction of magnetic lines of force around the wire”.

From the diagram, the multiplication symbol represents that the magnetic field is on the page.

According to Lenz law,

The direction of the induced current in the loop resists the true field that created the induced current initially.

The magnitude of the external magnetic field decreases.

The induced field in the loop due to the induced current should also be on the same side of the decreasing magnitude of the magnetic field.

According to the right-hand thumb rule, the clockwise current creates a magnetic field on the same side of the decreasing magnitude of the magnetic field.

The wrong option is,

• B. counterclockwise.

According to the right-hand thumb rule, the counterclockwise current creates a magnetic field on the opposite side of the direction of the decreasing magnitude of the magnetic field.

Therefore, counterclockwise cannot be the direction of the induced current.

Hence,

The correct option is,

• clockwise.

From the right-hand rule of thumb, only the clockwise current creates a magnetic field in the same direction as the decreasing magnitude of the magnetic field.

 

The direction of the induced current for picture A. is clockwise.