A coil of inductive reactance `31 Omega` has a resistance of `8 Omega`. It is placed in series with a condenser of capacitative reactance `25 Omega`. The combination is connected to an a.c. source of 110 volt. The power factor of the circuit is

Options

A. `0.64`
B. `0.80`
C. `0.33`
D. `0.56`

Answer

B

Explanation

Power factor, `phi = (R)/(sqrt(omegaL - (1)/(omegaC)^(2) + R^(2))) `
`(8)/(sqrt((31 - 25)^(2) + 8^(2))) = (8)/(sqrt(6^(2) + 8^(2)) ) = (8)/(10) = 0.8`