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Question: Answered & Verified by Expert

A particle (mass = m and charge = q) is moving in a region in which there exists a uniform electric field Ei^ and a uniform magnetic field Bk^. At t=0, the particle is at 0, a and is moving with vi^. After some time, the particle is located at 2a, 0 and has a velocity 2vj^, then which of the following is true?

PhysicsMagnetic Effects of CurrentJEE Main
Options:
  • A E=32mv2qa
  • B at the initial moment, the rate of work done by electric field is 34mv3a
  • C E=38mv2qa
  • D at the initial moment, the rate of work done by electric field is 316mv3a
Solution:
2182 Upvotes Verified Answer
The correct answer is: at the initial moment, the rate of work done by electric field is 34mv3a

By work energy theorem

Wmag+Wele=12m(2v)2-12m(v)2

0+qE02a=32mv2
E0=34mv2qa

Rate of work done at initial instant = power of electric force

=qE0V
=34mv3a

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