A wire 40 cm long bent into a rectangular loop `15 cmxx5 cm` is placed perpendicular to the magnetic field whose flux density is `0.8 Wbm ^(-2)`. Within 1.0 second, the loop is changed into a 10 cm square and flux density increases to 1.4 `Wbm^(-2)`. Calculate the value of induced emf.

Options

A. 16 mV
B. 10 mV
C. 8 mV
D. 4 mV

Answer

A

Explanation

`e=(dphi)/(dt)=(phi_(1)-phi_(2))/(dt)`
`=(A_(1)B_(1)-A_(2)B_(2))/(dt)`
`=(75xx10^(-4)xx0.8-100xx10^(-4)xx1.4)/(0.5)`
`=16xx10^(-3)V`