A circular loop and a square loop are formed from two wires of same length and cross section. Same current is passed through them. Then the ratio of their dipole moments is

Options

A. 4
B. `(2)/(pi)`
C. 2
D. `(4)/(pi)`

Explanation

Dipole moments due to current carrying circular wire M = iA
`"Here" " " (M_(1))/(M_(2))=(ipir^(2))/(1a^(2))=pi[((1)/(2pi))^(2)/(((1)/(4))^(2))]`
`=pi(16)/(4pi^(2))=(4)/(pi)`