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A flexible wire bent in the form of a ci...

A flexible wire bent in the form of a circle is place in a uniform magnetic field perpendicularly to the plane of the coil. The radius of the coil changes as shown in Figure. The graph of magnetude of induced emf in the coil is represented by

A

B

C

D

Text Solution

Verified by Experts

(b) Flux linked with the circular coil, `phi = BA`
`(d phi)/(dt) = B pi 2r (dr)/(dt)` therefore `(d phi)/(dt) alpha (dr)/(dt)`
Emf of coil `alpha (dr)/(dt) " and " e alpha r`
In 1 and 3 regions, r = constant `rArr emf = 0`
In 2 region, `(dr)/(dt) =` constant
Emf induced is increasing at constant rate, because r is increasing.
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