Answer:
0.7
Explanation:
f = 50 hz, R = 40 ohm, L = 0.3 h, C = 60 uC = 60 x 10^-6 c
XL = 2 x 3.14 x f x L = 2 x 3.14 x 50 x 0.3 = 94.2 ohm
Xc = 1 / ( 2 x 3.14 x 50 x 60 x 10^-6) = 53.078 ohm
Impedance is Z.
Z^2 = R^2 + ( XL - Xc)^2
Z^2 = 40^2 + (94.2 - 53.078)^2
Z^2 = 1600 + 1691.019
Z = 57.37 ohm
The power factor is given by
CosФ = r / Z = 40 / 57.37 = 0.697 = 0.7