Question

A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil will be-

• A. 2n B
• B. n² B
• C. n B
• D. 2n² B

Answer 1

Answer: (B)

n² B

Answer 2

B = but for same wire

n µ

\ B µ n² \ B' = n²B