A car antenna is 1.5 m long. The car is moving at (40 mph) under a DC high-tension wire with (100 amp) (the distance between the wire and the top of the antenna is 10m) . What emf is induced in the antenna and what is its polarity ? Solution emf is induced in the antenna = VBL 40mph = 17.881 m/s , B = u0I/(2piR) => emf = 17.881*4*3.14*10^-7100*1.5)/(2*3.14*10) = 0.000053643 V = 53.64 uV polarity will be in (VxB) direction.