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A rod of mass m and resistance R slides ...

A rod of mass m and resistance R slides smoothly over two parallel conducting wires kept sloping at an angle `theta` with respect to the horizontal as shown in figure. The circuit is closed through a perfect conductor at the top. There is a constant magnetic field `vecB` along the vertical direction. If the rod is initially at rest, find the velocity of the rod as a function of time.

A

B

C

D

Text Solution

Verified by Experts

The correct Answer is:
c
When the pebble is dropped , then initially its velocity increases . After sometime it becomes constant.
The viscous force acting on pebble through viscous oil `F=6pietarv` (where r= radius of pebble , v = velocity of pebble and `eta` = coefficient of viscosity)
As the viscous force is variable force ,hence acceleration is also variable so `vtot` graph will not be a straight line.
Hence , option (C ) is correct.
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Knowledge Check

  • A metallic rod of mass per unit length 0.5kgm^(-1) is lying horizontally on a smooth inclined plane which makes an angle of 30^(@) with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction 0.25 T is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is.

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