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Concepts Of Physics MCQ Edition [Volume 2]PhysicsMagnetic Field due to a Current

A particle is projected into a plane perpendicular to a uniform magnetic field. The area enclosed by the path traced by the particle is proportional to

Options

  1. Athe magnetic force
  2. Bthe velocity
  3. Cthe kinetic energy
  4. Dthe momentum

Correct answer

C. the kinetic energy

Step-by-step solution

When a charged particle is projected perpendicular to a uniform magnetic field, it moves in a circular path of radius r = mv qB . The area enclosed by this circular path is A = r^2 = ( mv qB )^2 = m^2 v^2 q^2 B^2 . The kinetic energy of the particle is K = 1 2 m v^2 , which gives m^2 v^2 = 2mK . Substituting this in the expression for area, we get: A = 2 m K q^2 B^2 Since m , q , and B are constants, A K . Thus, the area enclosed by the path is directly proportional to the kinetic energy of the particle.

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