Question

The magnetic field at the center of current carrying circular loop is $B_1$. The magnetic field at a distance of √3 times radius of the given circular loop from the center on its axis is $B_2$. The value of $B_1/B_2$ will be

• A. 9 : 4
• B. 12 : √5
• C. 8 : 1
• D. 5 : √3

Answer 1

Answer: (C)

8 : 1

Answer 2

$B_1 = \frac{μ0I}{2R}$

$B_2 = \frac{μ0IR^2}{2(R^2 + 3R^2)^{3/2} }= \frac{1}{8}(\frac{ μ0I}{2R}) = \frac{B_1}{8}\frac{B_1}{B_2} = \frac{8}{1}$