A solenoid is a long helical coil of wire through which a current is run in order to create a magnetic field. The magnetic field of the solenoid is the superposition of the fields due to the current through each coil. It is nearly uniform inside the solenoid and close to zero outside and is similar to the field of a bar magnet having a north pole at one end and a south pole at the other depending upon the direction of current flow. The magnetic field produced in the solenoid is dependent on a few factors such as, the current in the coil, number of turns per unit length etc. The following graph is obtained by a researcher while doing an experiment to see the variation of the magnetic field with respect to the current in the solenoid. The unit of magnetic field as given in the graph attached is in milli-Tesla (mT) and the current is given in Ampere.

What will happen if a soft iron bar is placed inside the solenoid?

Options

A. The bar will be electrocuted resulting in short circuit.
B. The bar will be magnetised as long as there is current in the circuit.
C. The bar will be magnetised permanently.
D. The bar will not be affected by any means.

Answer

B

Explanation

The magnetic field produced by the solenoid will be reinforced by the iron bar and it will be magnetised as long as there is current in the circuit