A circular loop has its radius increasing at a rate of 2

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A circular loop has its radius increasing at a rate of 2 m/s. The loop is placed perpendicular to a constant magnetic field 0.1 Wb/m2. When the radius of the loop is 2 m, the emf induced in the loop will be—

1. 0.8 π V
2. 0.04 π V
3. 0.2 π V
4. Zero

Correct Option: A

The area of the loop is A = π r²
Flux linking the area, φ = B × πr²

Induced emf, e(t) =	dφ
	dt

e (t) = d/ dt {B πr²} = B π 2r (dr/ dt)
or e (t) = 0.1 × π × 2 × 2 × 2 = 0.8 πV