What happens to the force acting on a current-carrying conductor placed in a magnetic field when : a] current in conductor increases ? b] length of the conductor increases ? c] direction of the current and magnetic field are reversed ? d] direction of the current is reversed without changing the direction of magnetic field ?

Explanation

a] The deflection of the compass needle increases because of the increase in the strength of the magnetic field [B `prop` l]
b] The direction of deflection of the compass needle is reversed because the direction of magnetic field is reversed.
c] The deflection on the compass needle decreases due to the decrease in the strength of the magnetic field [B `prop` 1/r].