A conducting rod is sliding on metal rails with velocity v.A magnetic field B is into the paper,the separation of the rails is L,and the resistance of the circuit is R.In what direction in the diagram is the current flowing in the resistor?
A) up
B) down
C) up then down
D) down then up
E) Insufficient information given,

Question

A conducting rod is sliding on metal rails with velocity v.A magnetic field B is into the paper,the separation of the rails is L,and the resistance of the circuit is R.In what direction in the diagram is the current flowing in the resistor? 
A) up 
B) down 
C) up then down 
D) down then up 
E) Insufficient information given,

Quizplus · Accepted Answer

As the conducting rod slides on the metal rails, it cuts through the magnetic field, which induces an EMF (electromotive force) in the rod according to Faraday's law. The direction of the induced EMF is given by Lenz's law, which states that the induced current flows in a direction that opposes the change in magnetic flux. In this case, since the magnetic field is into the paper and the rod is moving to the right, the induced current will flow in a direction such that it creates a magnetic field out of the paper to oppose the entering magnetic field. Using the right-hand rule for the direction of the induced current, we see that the current flows downward through the resistor. Therefore, the correct answer is B) down.

A Conducting Rod Is Sliding on Metal Rails with Velocity