A rectangular loop of sides `a` and `b` is placed in `xy`-placed. A uniform but time varying magnetic field of strength `B=20thati+10t^2hatj+50hatk` is present in the region. The magnitude of induced emf in the loop at time is

Options

A. 20+20t
B. 20
C. 20t
D. zero

Explanation

The area vector of loop `vec(A)=pm l b hatk`
& `vec(B)=10 t hati+10t^(2) hatj+50 hatk`
`:.` Magnetic flux is `phi=vec(B).vec(A)=pm 50 lb`
`:. Emf =(dphi)/(dt)=0`