Two straight parallel wires, both carrying 10 Ampere in the same direction attract each other with a force of `1xx10^(-3)N`. If both currents are doubled, what will be the force of attraction ?

Options

A. `1xx10^(-3)N`
B. `2xx10^(-3)N`
C. `4xx10^(-3)N`
D. `0.25xx10^(-3)N`

Answer

C

Explanation

The force acting between current carrying two parallel wires,
`F=(mu_(0)I_(1)I_(2)l)/(2pir)` (where `mu_(0)`, r and l are constant)
`thereforeFpropI_(1)I_(2)`
`therefore` When both currents are doubled the force,
`F_(1)prop4I_(1)I_(2)`
`thereforeF_(1)/F_(2)=(I_(1)I_(2))/(4I_(1)I_(2))`
`rArrF_(1)=4F=4xx10^(-3)N`