XPQY is a vertical smooth long loop having a total resistance R where PX is parallel to QY and separation between them is ℓ. A constant magnetic field B perpendicular to the plane of the loop exists in the entire space. A rod CD of length L (L > ℓ) and mass m is made to slide down from rest under the gravity as shown in figure. The terminal speed acquired by the rod is_______m/s.
(g = acceleration due to gravity)