A metal bar of length 0.4 is pushed at a constant speed of 8.3 m/s through a mag

Question

A metal bar of length 0.4 is pushed at a constant speed of 8.3 m/s through a magnetic field of 0.35 T. The magnetic field is directed out of the page. The bar makes electrical contact with and moves along frictionless metal rods attached to a light bulb of resistance 12 Cl. Give your reasoning to explain whether the flow of current on the side of the loop containing the bulb is up or down. Determine the magnitude of the induced voltage and the amount of current flowing through the bulb. State very dearly what would happen if the push applied to the bar was removed.

Explanation / Answer

When bar moves to right, magnetic flux increases. So induced current will be such that magnetic field due to induced current is directed into the page
For this current must be bottom to top in bulb
So electron must be top to bottom in side containing bulb

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E = B*L*v
= 0.35*0.4*8.3
= 1.162 V

magnitude of induced voltage = 1.162 V

induced current = induced voltage/R
= 1.162/12
= 0.097 A
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if force is removed
Bar will start decelerating that is velocity will start decreasing

induced emf = B*L*v will start decreasing

so induced current will start decreasing
so bulb will become less brighter and finnaly will be off

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