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THE IUG
PHYSB 1301
Quiz of chapter 11
DEPT. OF PHYSICS
TIME:10-min.
Choose the correct answer
1) In a purely capacitive AC circuit:
a) the current lags the voltage
c) the current is in phase with the voltage
b) the current leads the voltage
d) the current nad the voltage are out of phase.
2) In a purely resistive AC circuit:
a) the current lags the voltage
c) the current is in phase with the voltage
b) the current leads the voltage
d) the current nad the voltage are out of phase.
3) In a purely inductive AC circuit:
a) the current lags the voltage
c) the current is in phase with the voltage
b) the current leads the voltage
d) the current nad the voltage are out of phase.
4) A capacitor of 35 F is connected to a 400-Hz generator. The reactance of the capacitor is:
a) 11 
b) 71 
c) 0.014 
d) 0.088 
5) A capacitor of 35 F is connected to a 400-Hz generator. If the maximum emf of the generator is
20 V, the maximium current is:
a) 1.8 A
b) 0.28 A
c) 230 A
d) 1400 A
6) An inductor of 45 mH is connected to a 400-Hz generator. The reactance of the capacitor is:
a) 113 
b) 18 
c) 0.06 
d) 0.009 
7) An inductor of 45 mH is connected to a 400-Hz generator. If the maximum emf of the generator
is 20 V, the maximium current is:
a) 0.18 A
b) 1.1 A
c) 360 A
d) 2300 A
8) Which of the following statements is incorrect concerning the phasor:
a) It is a vector representing an AC quantity.
b) its magnitude represents the peak value of the quantity.
c) its projection on the vertical axis represents the instantaneous value of the quantity.
d) its projection on the horizontl axis represents the instantaneous value of the quantity.
9) Which of the following statements is correct concerning the phasor:
a) It is a clockwise rotating vector representing an AC quantity.
b) its magnitude represents the instantaneous value of the quantity.
c) its projection on the vertical axis represents the peak value of the quantity.
d) its projection on the vertical axis represents the instantaneous value of the quantity.
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10) Consider the voltage phasor shown at four instants of time. Choose the part of the figure that
represents the instant of time at which the instantaneous value of the voltage has the largest
magnitude.
(a)
a) a
(b)
b) b
(c)
(d)
c) c
d) d
11) Consider the voltage phasor shown at four instants of time. Choose the part of the figure that
represents the instant of time at which the instantaneous value of the voltage has the smallest
magnitude.
(a)
a) a
(b)
b) b
(c)
(d)
c) c
d) d
12) The figure shows the phasor diagram of a current and a voltage in AC
circuit.Which of the following is correct?
Vmax
a) the current lags the voltage.
b) the current leads the voltage.
c) the current are in phase with the d) the current are out of phase with
voltage.
the voltage.
13) The figure shows the phasor diagram of a current and a voltage in AC
circuit.Which of the following is correct?
Imax
Imax
a) the current lags the voltage.
b) the current leads the voltage.
c) the current are in phase with the d) the current are out of phase with
voltage.
the voltage.
14) The figure shows the phasor diagram of a current and a voltage in AC
circuit.Which of the following is correct?
Vmax
Vmax
Imax
a) the current lags the voltage.
b) the current leads the voltage.
c) the current are in phase with the d) the current are out of phase with
voltage.
the voltage.
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15) The rms value of an AC current is:
a) that steady current which produces the same rate of b) its average vaue.
heating in a resistor.
c) zero.
d) its peak value.
16) An AC source has an rms value of 100 V. Its maximum value is:
a) 141 V
b) 100 V
c) 71 V
d) 707 V
17) An AC source has a maximum value of 100 V. Its rms value is:
a) 71 V
b) 100 V
c) 141 V
d) 707 V
18) An AC source has an emf given by   200 sin 377t  . The frequency of the source is:
a) 60 Hz
b) 377 Hz
c) 200 Hz
d) 2369 Hz
19) An AC source has an emf given by   200 sin 377t  . The rms value of the voltage is:
a) 141 V
b) 200 V
c) 283 V
d) 150 V
20) The impedance of a series RLC circuit is increased if:
a) R increases.
b) R decreases.
c) C decreases.
d) L decreases.
21) A series RLC circuit has R= 4 , XC= 3  and XL=6 . The impedance of this circuit is:
a) 5 
b) 7 
c) 7.8 
d) 9.8 
22) A series RLC circuit has R= 4 , XC= 3  and XL=6 . If the rms value of the source is 210 V,
the current in the resistor is:
a) 42 A
b) 70 A
c) 35 A
d) 30 A
23) A series RLC circuit has R= 4 , XC= 3  and XL=6 . If the rms value of the source is 210 V,
the current in the capacitor is:
a) 42 A
b) 70 A
c) 35 A
d) 30 A
24) A series RLC circuit has R= 4 , XC= 3  and XL=6 . If the rms value of the source is 210 V,
the current in the inductor is:
a) 42 A
b) 70 A
c) 35 A
d) 30 A
25) In a series RLC circuit the maximum potential difference across R is 4 V, across the inductor is
6 V and across the capacitor is 3 V. The maximum emf of the source is:
a) 5 V
b) 13 V
c) 7 V
d) 25 V
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26) In a series RLC circuit the maximum potential difference across R is 6 V, across the inductor is
12 V and across the capacitor is 4 V. The maximum emf of the source is:
a) 10 V
b) 22 V
c) 2 V
d) 100 V
27) An RL series circuit the maximum emf is 20V. If the maximum potential difference across the
resistor is 16V, then the maximum potential difference across the inductor is:
a) 12 V
b) 16 V
c) 4 V
d) 36 V
28) In a series RLC AC circuit, if the current leads the voltage, then
a) XL < XC
b) XL > XC
c) XL = XC
d) in all cases
29) In a series RLC AC circuit, if the voltage leads the current, then
a) XL > XC
b) XL < XC
c) XL = XC
d) in all cases
30) In a series RLC circuit with alternating source. At resonance
a) Z = XC
b) Z=XL
c) Z=R
Z=XL+XC
31) In a series RLC AC circuit, the resonance occurred when
a) XL > XC
b) XL < XC
c) XL = XC
d) in all cases
32) In a series RLC circuit with alternating source. At resonance the impedance is:
a) Z > R
b) Z < R
c) Z=R
impossible to determine.
33) In a series RLC circuit with alternating source. At resonance:
a) the current has its maximum value.
c) the voltage has its maximum value.
b) the current has its minimum value.
d) the impedance has its maximum value.
34) In a series RLC circuit with alternating source, the resonance frequency is given by:
a)
1
LC
b)
1
LC
c) LC
LC
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