The horizontal component of earth's magnetic field at a certain place is ` 3xx 10^(-5) T` and the direction of the field is from the geographic south to the geographic north. A very long straight conductor is carrying a steady current of 1 A. What is the force per unit length on it when it is placed on a horizontal table and the direction of current is from east to west ?

Explanation

Here `B=3xx10^(-5)T`
`i=1A`
when the current is flowing from east to west and magnetic field is from south to north `theta=90^(@)`.
`F=Bi l sin theta =3xx 10^(-5)xxlxxsin 90^(@)`
`impliesF/l=3xx10^(-5)` N/m (downward)