In the figure below, a metal rod is forced to move with constant velocity v alon
ID: 1559287 • Letter: I
Question
In the figure below, a metal rod is forced to move with constant velocity v along two parallel metal rails, connected with a strip of metal at one end. A magnetic field B = 0.360 T points out of the page. (a) If the rails are separated by 27.0 cm and the speed of the rod is 70.0 cm/s, what emf is generated? (b) If the rod has a resistance of 21.0 Ohm and the rails and connector have negligible resistance, what is the current in the rod? (Include the sign taking counterclockwise to be positive.) (c) At what rate is energy being transferred to thermal energy?Explanation / Answer
(a) e = B L v
= (0.360 T) (0.27 m )(0.70 m/s)
= 0.068 Volt
(B) I = e / R = 0.068 / 21 = 3.24 x 10^-3 A
(C) P = e I
= (0.068) (3.24 x 10^-3)
= 2.203 x 10^-4 Watt