Two infinite long straight parallel wires A and B carry current of 4 A and 10 A respectively in opposite direction and are placed at 10 cm apart in vaccum. Find the force on 15 cm length of wire B.

Explanation

`I_(1) = 4A`
`I_(2) = 10A`
`r = 10cm = 10xx 10^(-2)m = 10^(-1)m`
Force on 15 cm length of wire `B = ?`
`l = 15cm = 15 xx 10^(-2)` m
`F = (mu_(0))/(4pi) (2I_(1)I_(2))/(r) xx l`
` = 10^(-7) xx (2 xx 4 xx 10)/(10^(-1)) xx 15 xx 10^(-2)`
`rArr = 1*2 xx 10^(-5)` N