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Rotational EMF

A circular co...

Question

A circular coil of conducting wire has an area A and number of turns N. It is lying in a vertical plane in a region where uniform magnetic field B exist with field direction normal to the coil plane. If the coil is rotated about a vertical axis by an angle $π$ in 0.5 seconds, then the value of the emf induced at the ends of the coil is

A

4 NAB

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B

4

π

NAB

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C

8 NAB

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D

8

π

NAB

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Solution

The correct option is B 4 NAB
AS the coil rotates by $π$ radians, $△ ϕ = N A B - (- N A B) = 2 N A B$

$e m f =$ rate of change of flux

$= \frac{△ ϕ}{△ t} = \frac{2 N A B}{0.5}$
$= 4 N A B$

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