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KVPY2015PhysicsElectrostatics

A point charge Q= (=3 10⁻¹² C ) rotates uniformly in a vertical circle of radius R =1 ~mm . The axis of the circle is aligned along the magnetic axis of the earth. At what value of the angular speed , the effective magnetic field at the center of the circle will be reduced to zero? (Horizontal component of Earth's magnetic field is 30 micro Tesla)

Options

  1. A10 ¹¹ rad / s
  2. B10⁹ rad / s
  3. C10¹³ rad / s
  4. D10⁷ rad / s

Correct answer

A. 10 ¹¹ rad / s

Step-by-step solution

₀ 2 R ( q 2 )=30 10⁻⁶ So =10¹¹ rad / s

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