A rectangular loop with a sliding conductor of length `l` is located in a uniform magnetic field perpendicular to the plane of loop. The magnetic induction perpendicular to the plane of loop Is equal to `B`. The part ad and be has electric resistance `R_1` and `R_2`, respectively. The conductor starts moving with constant acceleration `a_0`, at time `t = 0`. Neglecting the self-inductance of the loop and resistance of conductor. Find

(a) the current through the conductor during its motion.
(b) the polarity of `abcd` terminal.
(c) external force required to move the conductor with the given acceleration.