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Question
A rod AB moves with a uniform velocity v in a uniform magnetic field as shown in figure.
Options
The rod becomes electrically charged
The end A becomes positively charged
The end B becomes positively charged.
The rod becomes hot because of Joule heating
Solution
The end A becomes positively charged
Due to electromagnetic induction, emf e is induced across the ends of the rod. This induced emf is given by
`e=Bvl`
The direction of this induced emf is from A to B, that is, A is at the higher potential and B is at the lower potential. This is because the magnetic field exerts a force equal to `qvB` on each free electron where q is -1.6 × 10-16C. The force is towards AB by Fleming's left-hand rule; hence, negatively charged electrons move towards the end B and get accumulated near it. So, a negative charge appears at B and a positive charge appears at A.
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