A coil has an inductance of 0.7 H and is joined in series with a resistance of 220 ohm. Find the wattless component of current in the circuit, when an alternating e.m.f. of 220 V at a frequency of 50 Hz is supplied to it.

Options

A. `0.2 A`
B. `0.4A`
C. `0.5A`
D. `0.7A`

Answer

C

Explanation

`X_(L)=omega_(L)=2pifL=220 Omega`
`phi=tan^(-1)((X_(L))/R)= tan^(-1).(220)/(200)=45^(@)`
`I=E/(sqrt(R^(2)+X_(L)^(2)))=220/((220)^(2)+(220)^(2))`
Wattless component of current `=I sin phi`
`=1/(sqrt(2)). Sin 45^(@)=0.5A`