A conducting wire XY of mass $m$ and negligible resistance slides smoothly on two parallel conducting wire as shown in the fig. The closed circuit has a resistance R due to AC. AB and CD are perfect conductors. There is a magnetic field $B = B (+) \hat {k}$ If B is independent of time, obtain $V (t)$ assuming $V(0) = u_0$

Question

 

$(a) u_o e^{l^2B^2t/mR}$
$(b)- u_o e^{-l^2B^2t/mR}$
$(c) u_o e^{-l^2B^2t/mR}$
$(d) -u_o e^{l^2B^2t/mR}$