Question

Two wires of same length are bent to form the circular loop with two turns and a square loop of one turn. Both of them carry same current. The ratio of magnetic moment of circular loop of two turns to that of square loop is

• A. \(π:4\)
• B. \(4:π\)
• C. \(π:1\)
• D. \(2:π\)

Hint:

Flux density is flux over area, and permeability is B over H.

Answer 1

The Correct Option is D

Step 1: Relation:
$B = \mu H$ and $B = \frac\Phi A$, so $\mu = \frac{\Phi}{AH}$.

Step 2: Substitute:
$\mu = \frac{3\times10^{-4}}{1.5\times10^{-4}\times1000} = \frac{2}{1000} = 2\times10^{-3}$ (B).

Final Answer:
$2\times10^{-3}$ Wb/A-m. \[ \boxed{2\times10^{-3}\text{ Wb/A-m}} \]