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Concepts Of Physics MCQ Edition [Volume 2]PhysicsPermanent Magnets

A moving-coil galvanometer contains a 50 -turn coil with dimensions 2 cm 2 cm . It is suspended between magnetic poles that produce a magnetic field of 0.5 T . Determine the torque exerted on the coil by the magnetic field when a current of 20 mA flows through it.

Options

  1. A2 10⁻⁵ N m
  2. B4 10⁻⁴ N m
  3. C2 10⁻⁴ N m
  4. D1 10⁻⁴ N m

Correct answer

C. 2 10⁻⁴ N m

Step-by-step solution

Given: N = 50 A = 2 cm 2 cm = 4 10⁻⁴ m ^2 B = 0.5 T I = 20 mA = 20 10⁻³ A The torque on the coil in a moving-coil galvanometer with a radial magnetic field is given by: = NIAB Substituting the given values: = 50 (20 10⁻³) (4 10⁻⁴) 0.5 = 1000 10⁻³ 2 10⁻⁴ = 1 2 10⁻⁴ = 2 10⁻⁴ N m

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