either gets full credit
(c) gets 1/2 credit (1 point)
Vc = Vb R2/(R1+R2) = 6V/2 = 3 V
Q=CVc = (1µF)(3V) = 3 µC
Out of paper, in
the z direction.
sin(180°)
= 0 n•m
Text
Physics 141
2015 July 20
— Midterm Exam 2 – 90mins—
14. A sine-wave ac generator with Emax = 150 V and operating at 400 Hz is connected to a series RLC circuit
having R = 220 ⌦, L = 150 mH and C = 2.4 µF.
(a) Draw below the circuit diagram using standard symbols and label clearly.
(b) Draw below the phasor diagram showing the impedances of R, L and C and the total impedance of
the series circuit. Label clearly.
Circuit Diagram
Phasor Diagram
(c) Calculate the magnitude of the total impedance.
X L
Z
X
C
R
ω = 2π f = 63.7 rad/s
XL = ωL = 377 Ω
XC = 1/ωC = 166 Ω
2
2
Z= sqrt( R + (XL - XC) ) = 305 Ω
(d) Calculate the average power dissipated by the resistor.
<P> = 0.5 I
max
V
R
= 26.6 W
(e) Determine the phase shift between the generator voltage and the current.
φ = arctan( (XL – XC)/R) = 0.765 radians = 43.8 °
7