A conducting circular loop is placed in a uniform magnetic field, `B=0.025T` with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of `1 mms^(-1)`. The induced emf when the radius is `2 cm` is

Options

A. `2pimuV`
B. `pimuV`
C. `(pi)/(2)muV`
D. `2muV`

Answer

b

Explanation

Here , magnetic field ,B=0.025T
`therefore` Magnetic flux
`phi=B*A=B*pir^(2)`
Induced emf `|e|=(dphi)/(dt)`
`=Bpi2r*(Dr)/(dt)`
`=0.025xxpixx2xx10^(-2)xx1xx10^(-3)`
`=pimuV`