Question

A sheet is placed on horizontal surface in front of a strong magnetic pole. A force is needed to:

1. hold the sheet there if it is magnetic.
2. hold the sheet there if it is non-magnetic.
3. move the sheet away from the pole with uniform velocity if it is conducting.
4. move the sheet away from the pole with uniform velocity if it is both, non-conducting and nonpolar.

Choose the correct statement(s) from the options given below:

Options

• A, C and D only

• C only

• B and D only

• A and C only

Answer 1

A and C only

Explanation:

The statement A is correct. A magnetic sheet is attracted by the magnetic pole, so an external force is needed to hold it in place. Statement B is incorrect. A non-magnetic sheet is not attracted, so no force is required. The statement C is correct. A conducting sheet moving in a magnetic field experiences eddy currents, which oppose motion (Lenz’s law), so force is needed to move it with uniform velocity. The statement D is incorrect. A non-conducting, non-polar sheet does not interact with the magnetic field, so no force is needed. Hence, the correct statements are A and C only.