A straight horizontal conducting rod of length 0.45 m and mass 60 g is suspended by two vertical wires at its ends. A current of 5.0 A is set up in the rod through the wires. (a) What magnetic field should be set up normal to the conductor in order that the tension in the wires is zero? (b) What will be the total tension in the wires if the direction of current is reversed, keeping the magnetic field same as before?

Explanation

(a) A horizontal magnetic field of magnitude 0.26 T normal to the conductor in such a direction that Fleming’s left-hand rule gives a magnetic force upward. (b) 1.176 N.