The resultant force on a square current loop PQRS due to a long current carrying conductor will be (if the current flow in the loop is clockwise)

Options

A. zero
B. `0.36 xx 10^(-3)N`
C. `2.5 xx 10^(-3)N`
D. `5 xx 10^(-4)N`

Answer

D

Explanation

`F_("loop") = (mu_(0)I_(1)I_(2) xx 1)/(2pi)[(1)/(d) - (1)/(d + 1)]`
`= (4pi xx 10^(-7) xx 30 xx 20 xx 1 xx 10^(-1))/(2pi) [(1)/(2 xx 10^(-2))-(1)/(0.12)]`
`= 12 xx 10^(-6)[(100)/(2)-(100)/(12)]`
`= 12 xx 10^(-6)[50-(25)/(3)]`
`= 12 xx 10^(-6)[(125)/(3)]`
`= 500 xx 10^(-6) = 5 xx 10^(-4)N`