Question

The coereivity of a small bar magnet is 4 × 10³Amp/m. It is inserted inside a solenoid of 500 turns and length 1 m to demagnetise it. The amount of current to be passed through the solenoid will be

• A. 2.5 A
• B. 5 A
• C. 8 A
• D. 10 A

Answer 1

Answer: (C)

8 A

Answer 2

H = ni ⇒ $i = \frac { H } { n } = \frac { 4 \times 10 ^ { 3 } } { 500 } = 8 A$