(1)cd进入时,感应电动势E=BLV,ab两端电压U1=1/4E=1/4BLV,cd离开时ab切割磁感线则U2=3/4BLV
(2)当ab或cd一边切割磁感线时产生热量则Q=2E^2t/R=2E^2(L/V)/R=2bB^2L^3V/R