Question

A current clamp is an electrical device used to measure current in a conductor without making any physical contact with the conducting part of the conductor. The current clamp has jaws that clamp around the conductor as shown below. Some current clamps work on the principle of electromagnetic induction and hence can measure only alternating current. Give a reason why direct current cannot be measured by these current clamps.

Two statements are given below - one labelled Assertion (A) and the other labelled Reason (R). Read the statements carefully and choose the option that correctly describes statements A and R. Assertion (A): In an AC electric generator, a current is induced in the coil as the coil rotates between the poles of a permanent magnet. Reason (R): The force due to the magnetic field makes the coil rotate in an AC electric generator. Which of the following is correct?

A stationary metal coil is placed in a magnetic field. The strength of the magnetic field varies with time as shown in the graph below. In which of the time intervals(s) is a current induced in the coil?

A small bar magnet is dropped vertically from rest into a long coil of wire, and it leaves from the other end as shown in the diagram below. Compare the magnitude and direction of - the induced current in the coil when the magnet enters the coil, with - the induced current in the coil when it leaves the coil.