A long straight wire carrying current of 30 A rests on a table. Another wire AB of length 1 m, mass 3 g carries the same current but in the opposite direction, the wire AB is free to slide up and down. The height upto which AB will rise is

Options

A. 0.6 cm
B. 0.7 cm
C. 0.4 cm
D. 0.5 cm

Answer

A

Explanation

Here `I_(1)=I_(2) = 30A, l = 1m, m = 3 g = 3xx10^(-3)kg`
In equilibrium position ,
`mg=(mu_(0))/(4pi)(2I_(1)I_(2)l)/(h), h=(mu_(0))/(4pi)xx(2I_(1)I_(2)l)/(mg)`
`h=10^(-7)xx(2xx30xx30xx1)/(3xx10^(-3)xx10)=0.6cm`