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KCET2021PhysicsElectrostatics

A 2 ~g object, located in a region of uniform electric field E = (300 NC ⁻¹ ) i carries a charge Q . The object released from rest at x=0 , has a kinetic energy of 0.12 ~J at x=0.5 ~m . Then, Q is

Options

  1. A400 C
  2. B-400 C
  3. C800 C
  4. D-800 C

Correct answer

C. 800 C

Step-by-step solution

Given, m=2 g=2 10⁻³ ~kg E = (300 NC ⁻¹ ) i At, x=0,( KE )₁=0 and x=0.5 ~m ,( KE )₂=0.12 ~J From work-energy theorem, work done = change in kinetic energy aligned & Force displacement = KE & aligned Q E d &= KE ₂- KE ₁ & Q 300 0.5=0.12 or & Q= 0.12 300 0.5 =800 C aligned aligned The charge Q is moving in the direction of electric field. Hence, it is positive.

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