Question

One can demagnetise a magnet using current by

• A. Placing the permanent magnet in a solenoid which is placed along East-West of the earth and then passing a direct current through the coil.
• B. Placing the permanent magnet in a solenoid which is placed along East-West of the earth and then passing an alternating current through the coil.
• C. Placing the permanent magnet in a solenoid which is placed along North-South of the earth and then passing an alternating current through the coil.
• D. Placing the permanent magnet in a solenoid which is placed along North-South of the earth and then passing a direct current through the coil.
• E. Placing the permanent magnet in a coil with single turn which is placed along North-South of the earth and then passing an alternating current through the coil.

Answer 1

The correct option is B

Placing the permanent magnet in a solenoid which is placed along East-West of the earth and then passing an alternating current through the coil.

Place the permanent magnet in a solenoid which is placed along East-West of the earth and then pass an alternating current through the coil. The alternating current will continuously reverse the polarity of the coil. This in turn will disorient the small atomic magnets of the permanent magnet and demagnetise the permanent magnet.