Question

ABCD is a square loop made of an uniform conducting wire. The current enters the loop at A and leaves at D. The magnetic field is

• A. Zero at all points outside the loop
• B. Zero at all points inside the loop
• C. Zero only at the centre of the loop
• D. Maximum at the centre of the loop.

Answer 1

Answer: (C)

Zero only at the centre of the loop

Answer 2

B at centre due to a straight conductor = $\frac{\mu_0}{4\pi}$1 (sin $\alpha$ + sin $\beta$)
Net B at centre comes out to be zero