A coil of circular cross - section having 1000 turns and `4cm^(2)` face area is placed with its axis parallel to a magnetic field which decreases by `10^(-2)"Wb m"^(-2)` in 0.01 s. the e.m.f induced in the coil is :

Options

A. 400 mV
B. 200 mV
C. 4 m V
D. 0.4 MV

Answer

A

Explanation

The emf induced
`epsilon= (dphi)/(dt)= NA(db)/(dt)`
`= 1000 xx 4 xx 10^(-4) xx (10^(-2))/(0.01)`
`= 4 xx 10^(-3) xx 10^(+2)`
= 0.4 V = 400 mV