Question

A very small circular loop of radius a is initially (at t = 0) coplaner and concentric with a much larger fixed circular loop of radius b. A constant I flows in the larger loop. The smaller loop is rotated with a constant angular speed `omega` about the common diameter. The emf induced in the smaller loop as a function of time t is
A. `(pia^(2)mu_(0)I)/(2b)omegacos(omegat)`
B. `(pia^(2)mu_(0)I)/(2b)omegasin(omega^(2)t^(2))`
C. `(pia^(2)mu_(0)I)/(2b)omegasin(omegat)`
D. `(pia^(2)mu_(0)I)/(2b)omegasin^(2)(omegat)`

Answer 1

Correct Answer - C
`B=(mu_(0)I)/(2b),A=pia^(2)`
`phi=vecB.vecA=BAcosomegat`
`e=-(dphi)/(dt)=-(mu_(0)I)/(2b).pia^(2)(-omegasinomegat)`
`=(mu_(0)Ipia^(2))/(2b)omegasinomegat`