A square loop of side \(a=50 \mathrm{~cm}\) is suspended from the left arm of a scale, which is kept at equilibrium by adding weights to the right side. The lower half of the loop is in a uniform magnetic field of magnitude \(0.4 \mathrm{~T}\), orthogonal to the surface of the loop, but the upper half is outside the magnetic field.

(a) It is observed that when a current \(I\) flows in the loop, one needs to add \(25 \mathrm{~g}\) to the right arm to bring the scale back to equilibrium. Find the current flowing in the loop.

(b) If the direction of current were now to be reversed, what would need to be done to bring the scale back to equilibrium?