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A current carrying circular loop is perpendicular to a magnetic field of induction 10⁻⁴ ~T . If the radius of the loop starts shrinking at a uniform rate of 2 mms ⁻¹ , then the emf induced in the loop at the instant, when its radius is 20 ~cm will be

Options

  1. A0.02 V
  2. B0.08 V
  3. C0.03 V
  4. D0.05 V

Correct answer

B. 0.08 V

Step-by-step solution

Given, B=10⁻⁴ ~T , r=20 ~cm =20 10⁻² ~m d r d t =- 2 ~mm ~s =-2 10⁻³ m s Induced emf, =- d d t =- d d t (B r^2 ) aligned & =-B d r^2 d t =-B (2 r d r d t ) & =10⁻⁴ 2 20 10⁻² 2 10⁻³ & =8 10⁻⁸=0.08 ( V ) aligned

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