The diagram below illustrates an a.c.source of 50V(r.m.s.), (frac{100}{pi})Hz connected in series with an inductor of inductor of inductance L and a resistor of resistance R. The current in the circuit is 2A and the p.d across L and R are 30V and 40V respectively. Calculate the power factor of the circuit
-
A.
1.33 -
B.
1.25 -
C.
0.80 -
D.
0.75 -
E.
0.60
Correct Answer: Option C
Explanation
cos(theta = frac{R}{Z})
R = (frac{V}{I} = frac{40}{2} = 20)
Z² = R² + (^X_L)² = 20² + 15² = √625 = 25
cos (theta = frac{R}{Z} = frac{20}{25} = 0.8)