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4. (-/5 Points] DETAILS SERPSE10 30.A.P.038. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER In the figure below, the rolling axle, 2.70 m long, is pushed along horizontal rails at a constant speed v = 9.00 m/s. A resistor R = 0.4000 2 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 field B = 0.0300 T is vertically downward. B thi R (a) Find the induced current I in the resistor. (b) What horizontal force F is required to keep the axle rolling at constant speed? N (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 bare 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.