A straight horizontal conducrting rod of length `0.45m ` and mass 60g is suspended by two vertical wires at its ends. A current of `5.0A is set up in the rod through the wires.
What magnetic field should be set up nromal to the conductor in order that the tension in the wires is zero ?

Explanation

To kept the tension in the wire zero, the upward force exerted by the magnetic field should be neutralised by the downward force extered by gravity (weight of the rod).
`:.Bil =mg`
`:. B=(mg)/(Il)=(60xx10^(-3)xx9.8)/(5xx0.45)=0.26T`