A coil has resistance `30 ohm` and inductive reactance `20 ohm` at `50 Hz` frequency. If an ac source of 200 volts. `100 Hz`, is connected across the coil, the current in the coil will be

Options

A. 2.0 A
B. 4.0 A
C. 8.0 A
D. `(20)/(sqrt13)` A

Answer

B

Explanation

`X_L=2pifL`
`X_Lpropf`
`(X_(L_2))/(X_(L_1))=(f_2)/(f_1)impliesX_(L_2)=40Omega`
`R=30Omega`
`Z=sqrt((30)^2+(40)^2)=50Omega`
`I=V/Z=200/50=4A`