A resistor with R = 320 and an inductor are connected in series across an ac sou
ID: 1794972 • Letter: A
Question
A resistor with R = 320 and an inductor are connected in series across an ac source that has voltage amplitude 500 V . The rate at which electrical energy is dissipated in the resistor is 316 W .
Part A
What is the impedance Z of the circuit?
Express your answer to three significant figures and include the appropriate units.
Part B
What is the amplitude of the voltage across the inductor?
Express your answer to three significant figures and include the appropriate units.
Part C
What is the power factor?
Express your answer using three significant figures.
Explanation / Answer
power P = RI^2 and from here you have that
I = sqrt(P/R) = 0.99
A which is effective value of current.
effective value of voltage =500*sqrt(2)/2 = 353.56 V
impedance = effective value of voltage /effective value of current
Z = V/I = 357.13 .
Now that you have impedance and
Z^2 = R^2 + X^2
X = 158.56 so effective value of voltage across inductor is U1 = X*I = 156.97 V
and power factor is cos = R/Z = 0.896