Question

Identify the expression for the magnetic field on the axis of circular loop.

(a) B=\( \frac {\mu_o Ir}{4 \pi \big ( (r^2 \, + \, x^2)^{\frac {1}{2}} \big ] } \)  × 2πr

(b) B=\( \frac {\mu_o Ir}{4 \pi \big ( (r^2 \, + \, x^2)^{\frac {3}{2}} \big ] } \)

(c) B=\( \frac {\mu_o Ir}{4 \pi \big ( (r^2 \, + \, x^2)^{\frac {3}{2}} \big ] } \)  × 2πr

(d) B=\(  \frac {\mu_o Ir}{4 \pi \big ( (r^2 \, + \, x^2)^{\frac {1}{2}} \big ] } \)  × 4πr

I got this question during an interview.

My enquiry is from Magnetic Field on the Axis of a Circular Current Loop in portion Moving Charges and Magnetism of Physics – Class 12

Answer 1

Correct answer is (c) B=\( \frac {\mu_o Ir}{4 \pi \big ( (r^2 \, + \, x^2)^{\frac {3}{2}} \big ] } \)  × 2πr

Best explanation: The expression for magnetic field on the axis of circular loop is given as:

B=\( \frac {\mu_o Ir}{4 \pi \big ( (r^2 \, + \, x^2)^{\frac {3}{2}} \big ] } \)  × 2πr

It is towards the loop if current in it is in clockwise direction and it is away from the loop if current in it is in anticlockwise direction.