A uniform magnetic field `B` exists in a cylindrical region of radius `I0cm` as shown in figure. A uniform wire or length `80cm` and resistance `44.0Omega` is bent into a square frame and is placed with one side along a diameter of the cylindrical region. if the magnetic field increases at a constant rate of `0.0I0T//sec` , the current induced in the frame

Options

A. `3.9xx10^(-5)A`
B. `4.0xx10^(-5)A`
C. `4.1xx10^(-5)A`
D. `3.9xx10^(-4)A`

Answer

A

Explanation

Only half area of ring will be considered.
`phi=BA=B.(pir^(2))/(2)`
`e=(dphi)/(dt)=(pir^(2))/(2).(dB)/(dt)=(pi(0.1)^(2))/(2)xx0.01=(pi)/(2)xx10^(-4)V`
`i=(e)/(R)=((pi)/(2)xx10^(-4))/(4)=3.9xx10^(-5)A`