A wire of length 4 m carrying current I A is bent in the form of a circle. Its magnetic moment will be:

$\frac{4I}{π}$

The correct answer is Option (2) → $\frac{4I}{π}$

Given,

$l$, length of wire = 4 m

I, current flowing = IA

M, magnetic moment = N.I.A

where,

N = Number of turns

I = Current (A)

A = area of enclosed loop

Now,

$l$, length of the wire = circumference of the circle

$l=2πr$

$r=\frac{l}{2π}=\frac{4}{2π}=\frac{2}{π}$

Area of enclose loop = $πr^2$

$=π×\frac{2}{π}×\frac{2}{π}$

$=\frac{4}{π}$

$∴M=1.I.\frac{4}{π}$

$M=\frac{4I}{π}$