A coil has an area of `0.05 m^2` and has 800 turns. After placing the coil in a magnetic field of strength `4 xx 10^(-5) "Wb/m"^2` perpendicular to the field the coil is rotated through `90^@` in 0.1 s. The average emf induced is ____

Options

A. zero
B. 0.016 V
C. 0.01 V
D. 0.032 V

Answer

B

Explanation

`N Deltaphi=N(phi_2-phi_1)`
`=N(AB cosphi_2 -AB cos phi_1)`
`=NAB (cos theta_2 - cos theta_1)`
`=800xx5xx10^(-2)xx4xx10^(-5)("cos"pi/2- cos0^@)`
`=160xx10^(-5)[0-1]`
`=-160xx10^(-5)` Wb
`therefore epsilon=-(N Deltaphi)/(Deltat)=(160xx10^(-5))/0.1 =160xx10^(-4)`
`therefore epsilon` =0.016 V