In the figure below, the rolling axle, 2.70 m long, is pushed along horizontal r
ID: 1774322 • Letter: I
Question
In the figure below, the rolling axle, 2.70 m long, is pushed along horizontal rails at a constant speed v= 13.00 m/s. A resistor R= 0.4000 is connected to the rails at points a and b, directly opposite each other. The wheels make good electrical contact with the rails, so the axle, rails, and R form a closed-loop circuit. The only significant resistance in the circuit is R. A uniform magnetic d s 01300 is vertically downward. RTT (a) Find the induced current I in the resistor. (b) What horizontal force Fis required to keep the axle rolling at constant speed? (c) Which end of the resistor, a or b, is at the higher electric potential? O Point a is at a higher potential. O Point b is at a higher potential O Point a and point b are at equal potentials. (d) After the axle rolls past the resistor, does the current in R reverse direction? O Yes O No Explain your answer. This answer has not been graded yet.Explanation / Answer
(a)induced current=induced emf / resistance
induced emf =magnetic field x axle length xspeed
induced current=0.13 x 2.7 x 13 / 0.4 = 11.4075 A
(b) force=magnetic field x current x length of axle=0.13x11.4075x2.7
= 4N
(c) point b
(d) No.
Explanation: Both the velocity and the B field are unchanged (current continues to go through the resistor).