Electromagnetic Induction - Result Question 10

10. A conducting circular loop is placed in a uniform magnetic field, B=0.025T with its plane perpendicular to the loop.

[2010]

The radius of the loop is made to shrink at a constant rate of 1mms1. The induced e.m.f. when the radius is 2cm, is

(a) 2πμV

(b) πμV

(c) π2μV

(d) 2μV

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Answer:

Correct Answer: 10. (b)

Solution:

  1. (b) Magnetic flux linked with the loop is ϕ=Bπr2

|e|=dϕdt=Bπ2rdrdt

When r=2cm,drdt=1mms1

e=0.025×π×2×2×102×103

=0.100×π×105=π×106V=πμV



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