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Concepts Of Physics MCQ Edition [Volume 2]PhysicsElectromagnetic Induction

As shown in the figure, a rod AB travels with a uniform velocity v within a uniform magnetic field.

Options

  1. AThe end B develops a positive charge.
  2. BThe rod becomes hot due to Joule heating.
  3. CThe rod acquires an overall electrical charge.
  4. DThe end A develops a positive charge.

Correct answer

D. The end A develops a positive charge.

Step-by-step solution

The magnetic Lorentz force on a charge q moving with velocity v in a magnetic field B is given by F = q( v B ) . The velocity v is directed towards the right and the magnetic field B is directed into the plane of the paper. By the right-hand rule, the direction of the cross product ( v B ) is upwards, towards end A . Free electrons in the conducting rod have a negative charge ( q = -e ), so they experience a magnetic force in the opposite direction, i.e., downwards towards end B . As a result, electrons accumulate

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