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Electric Charges And Fields

Question
CBSEENPH12039980

A conducting circular loop is placed in a uniform magnetic field, B = 0.0025 T with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of 1 mms-1. The induced emf when the radius is 2 cm, is

  • 2 πμ V

  • πμ V

  • πμ V/2

  • 2μV

Solution

B.

πμ V

Magnetic space flux space straight ϕ space equals space straight B. straight A
space equals space straight B. space πr squared
Induced space emf comma space vertical line straight e vertical line space equals space dϕ over dt space equals space Bπ space 2 straight r space dr over dt
space equals space 0.025 space straight x space straight pi space straight x space 2 space straight x space 2 space straight x space 10 to the power of negative 2 end exponent space straight x space 1 space straight x space 10 to the power of negative 3 end exponent
space equals space πμV