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. `5` ampere
B. `0.5` ampere
C. `0.7` ampere
D. `7` ampere

Answer

B

Explanation

Wattless component of `AC=I_(v)sin theta=(E_(v))/Z sin theta`
`=220/(sqrt(R^(2)+L^(2)omega^(2)))=0.7xx2xx22/7xx50`
`=(220xx(0.7xx2pixx50))/((220^(2)+220^(2)))=220 Omega`
`I=(220xx220)/(220^(2)(2))=1/2 =0.5A`