Question

A long straight wire carrying current of `25A` rests on a table as shown in figure. Another wire PQ of length 1m, mass `2*5g` carries the same current but in the opposite direction. The wire PQ is free to slide up and down. To what height will PQ rise?

Answer 1

Here, `I_1=25A, I_2=25A, l=1m, m=2*5g=2*5xx10^-3kg`
In equilibrium position
`mg=(mu_0)/(4pi)(2I_1I_2l)/(h)`
or `h=(mu_0)/(4pi)(2I_1I_2l)/(mg)=(10^-7xx2xx25xx25xx1)/((2.5xx10^-3)xx9*8)=51xx10^-4m=0*51cm`