Current in the loop PQRS,
I = \(\frac{ε}{r}\)
Since ε = \(\frac{dφ}{dt}\) BIv So, I = \(\frac{BIv}{r}\)
(ii) The force required to keep the arm PQ in
Constant motion
F = BI =l = B\(\Big(\frac{BIv}{r}\Big)l\) = \(\frac{B^2l^2v}{r}\)
(iii) Power required to move the arm PQ