We know that if an electric current (I) is passed through a conductor of length l placed in a magnetic field (B), then the force acting :

F = BIL                              ... (1)

(i) If the current is increased, then from eq. (1), F ∝ I i.e., Rod AB is more displaced.

(ii) If a stronger horse-shoe magnet is used then from eq. (1), F ∝ B, i.e., Rod AB is more displaced.

(iii) If the length of rod AB is increased, then from eq. (1), F ∝ l, i.e., Rod AB is more displaced.