\( B A C D \) is a fixed conducting smooth rail placed in a vertical plane. \( P Q \) is a condu....

\( B A C D \) is a fixed conducting smooth rail placed in a vertical plane. \( P Q \) is a conducting rod which is free to slide on the rails. A horizontal uniform magnetic field exists in space as shown. If the \( \operatorname{rod} P Q \) is
\( \mathrm{P} \)
released from rest then,
(1) The \( \operatorname{rod} P Q \) will move downward with constant acceleration
(2) The rod \( P Q \) will move upward with constant acceleration
(3) The rod will move downward with decreasing acceleration and finally acquire a constant velocity
(4) Either \( A \) or \( B \)