As shown in the figure below, you exert a constant force F to the right on a con

Question

As shown in the figure below, you exert a constant force F to the right on a conducting rod of length 20.0 cm that can move without friction along a pair of conducting rails. The rails are connected at the left end by a resistor of resistance 40.0 , and we can assume that the resistance of each rail and the rod is negligible in comparison to the resistance of the resistor. There is a uniform magnetic field of magnitude 4.00 T directed into the page, and the rod begins from rest. Both the rails and the magnetic field extend a long way to the right. Note that you should be able to do this problem without a calculator.

(a) A long time after the rod begins to move, it reaches a constant speed of 2.00 m/s. When the rod reaches its maximum speed, what is the magnitude of the induced current in the loop?
A

In what direction is this induced current?

clockwisecounterclockwise    

(b) What is the magnitude of the constant force F you exert on the rod for the rod to reach a maximum speed of 2.00 m/s?
N

Explanation / Answer

Here ,

a) let the induced current is I

I = emf/R

I = B* v * L/R

I = 4 * 2 * 0.20/40

I = 0.04 A

the current in the loop is 0.04 A

b)

as the flux in the loop is increasing

Using Lenz's law

the direction of induced current is ANTICLOCKWISE

c)

for the constant force ,

F = B*I*L

F = 4 * 0.04 * 0.2

F = 0.032 N

the magnitude of the constant force F is 0.032 N

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