Question 1

The impedance of the parallel RLC circuit shown is given by

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 2

Determine the impedance for the circuit. ​   ​

Accepted Answer

A)  600 Ω 
B)  1200 Ω 
C)  1800 Ω 
D)  2300 Ω 
E)  1100 Ω 
A)  600 Ω 
B)  1200 Ω 
C)  1800 Ω 
D)  2300 Ω 
E)  1100 Ω

Question 3

What is the average power dissipation in an RLC series circuit with R = 10Ω, L = 0.1 H, C = 10 μF when driven at resonance by a 100 V-rms source?

Accepted Answer

A)  100 W 
B)  500 W 
C)  1000 W 
D)  2 kW 
E)  700 W 
A)  100 W 
B)  500 W 
C)  1000 W 
D)  2 kW 
E)  700 W

Question 4

If the input to an RLC series circuit is V = Vm cos ωt, then the current in the circuit is

Accepted Answer

A) 
  cos ωt 
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  cos ωt 
B) 
  
C) 
  
D) 
  
E)

Question 5

A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RL circuit with R = 10.0 Ω and L = 10.0 mH. The impedance is

Accepted Answer

A)  3.77 Ω. 
B)  9.26 Ω. 
C)  10.0 Ω. 
D)  10.7 Ω. 
E)  13.8 Ω. 
A)  3.77 Ω. 
B)  9.26 Ω. 
C)  10.0 Ω. 
D)  10.7 Ω. 
E)  13.8 Ω.

Question 6

A 10-μF capacitor in an LC circuit made entirely of superconducting materials (R = 0 Ω) is charged to 100 μC. Then a superconducting switch is closed. At t = 0 s, plate 1 is positively charged and plate 2 is negatively charged. At a later time, Vab = +10 V. At that time, Vdc is

Accepted Answer

A)  0 V. 
B)  3.54 V. 
C)  5.0 V. 
D)  7.07 V. 
E)  10 V. 
A)  0 V. 
B)  3.54 V. 
C)  5.0 V. 
D)  7.07 V. 
E)  10 V.

Question 7

A step-up transformer has an input voltage of 110 V (rms). There are 100 turns on the primary and 1500 on the secondary. What is the output voltage?

Accepted Answer

A)  1 600 V (max) 
B)  1 650 V (rms) 
C)  3 260 V (max) 
D)  165 kV (rms) 
E)  7.3 V (rms) 
A)  1 600 V (max) 
B)  1 650 V (rms) 
C)  3 260 V (max) 
D)  165 kV (rms) 
E)  7.3 V (rms)

Question 8

At what frequency will a 50.0-mH inductor have a reactance XL = 700Ω?

Accepted Answer

A)  352 Hz 
B)  777 Hz 
C)  1.25 kHz 
D)  2.23 kHz 
E)  14 kHz 
A)  352 Hz 
B)  777 Hz 
C)  1.25 kHz 
D)  2.23 kHz 
E)  14 kHz

Question 9

Determine the rms voltage drop across the resistor in the circuit.

Accepted Answer

A)  55 V 
B)  77 V 
C)  9.9 V 
D)  5.5 V 
E)  61 V 
A)  55 V 
B)  77 V 
C)  9.9 V 
D)  5.5 V 
E)  61 V

Question 10

In a typical transmission line, the current I is very small and the voltage V is very large. A unit length of line has resistance R. For a power line that supplies power to 10000 households, we can conclude that

Accepted Answer

A)  IV = I2R. 
B)  I = V/R. 
C)  IV 2R. 
D)  IV > I2R. 
E)  I2R = 0. 
A)  IV = I2R. 
B)  I = V/R. 
C)  IV 2R. 
D)  IV > I2R. 
E)  I2R = 0.

Question 11

Which of the following is true about a diode?

Accepted Answer

A)  A diode causes the voltage to shift in phase by 90°, i.e., a right angle. 
B)  A diode has high resistance in one current direction and low resistance in the opposite current direction. 
C)  A diode can only be used with a transformer. 
D)  All filter circuits contain a diode. 
E)  All of the above. 
A)  A diode causes the voltage to shift in phase by 90°, i.e., a right angle. 
B)  A diode has high resistance in one current direction and low resistance in the opposite current direction. 
C)  A diode can only be used with a transformer. 
D)  All filter circuits contain a diode. 
E)  All of the above.

Question 12

At what frequency will a 12-μF capacitor have a reactance XC = 300Ω?

Accepted Answer

A)  44 Hz 
B)  88 Hz 
C)  180 Hz 
D)  350 Hz 
E)  280 Hz 
A)  44 Hz 
B)  88 Hz 
C)  180 Hz 
D)  350 Hz 
E)  280 Hz

Question 13

A 230000 V-rms powerline carries an average power Pavg = 250 MW a distance of 200 km. If the total resistance of the cables is 10 ohms, what is the resistive power loss?

Accepted Answer

A)  1.0 MW 
B)  2.5 MW 
C)  5.4 MW 
D)  12 MW 
E)  10 kW 
A)  1.0 MW 
B)  2.5 MW 
C)  5.4 MW 
D)  12 MW 
E)  10 kW

Question 14

A series RLC circuit has an impedance of 120Ω and a resistance of 64Ω. What average power is delivered to this circuit when Vrms = 90 volts?

Accepted Answer

A)  36 W 
B)  100 W 
C)  192 W 
D)  360 W 
E)  12 W 
A)  36 W 
B)  100 W 
C)  192 W 
D)  360 W 
E)  12 W

Question 15

Whenever the alternating current frequency in a series RLC circuit is halved,

Accepted Answer

A)  the inductive reactance is doubled and the capacitive reactance is halved. 
B)  the inductive reactance is doubled and the capacitive reactance is doubled. 
C)  the inductive reactance is halved and the capacitive reactance is halved. 
D)  the inductive reactance is halved and the capacitive reactance is doubled. 
E)  the reactance of the circuit remains the same. 
A)  the inductive reactance is doubled and the capacitive reactance is halved. 
B)  the inductive reactance is doubled and the capacitive reactance is doubled. 
C)  the inductive reactance is halved and the capacitive reactance is halved. 
D)  the inductive reactance is halved and the capacitive reactance is doubled. 
E)  the reactance of the circuit remains the same.

Question 16

A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RC circuit with R = 10.0 Ω and C = 300 μF. The peak current in the circuit is

Accepted Answer

A)  8.24 A. 
B)  8.84 A. 
C)  11.0 A. 
D)  12.4 A. 
E)  23.5 A. 
A)  8.24 A. 
B)  8.84 A. 
C)  11.0 A. 
D)  12.4 A. 
E)  23.5 A.

Question 17

Capacitive reactance XC is given by

Accepted Answer

A)  1/ωC 
B)  ωC 
C)  ω/C 
D)  C/ω 
E)  1/ω2C 
A)  1/ωC 
B)  ωC 
C)  ω/C 
D)  C/ω 
E)  1/ω2C

Question 18

Determine the rms current for the circuit.

Accepted Answer

A)  55 mA 
B)  77 mA 
C)  99 mA 
D)  0.19 A 
E)  61 mA 
A)  55 mA 
B)  77 mA 
C)  99 mA 
D)  0.19 A 
E)  61 mA

Question 19

Calculate Vout/Vin for the circuit if R = 2.0 kΩ, C = 0.020 μF and V = 140V sin(50000t). ​   ​

Accepted Answer

A)  0.02 
B)  0.45 
C)  0.80 
D)  0.98 
E)  2.2 
A)  0.02 
B)  0.45 
C)  0.80 
D)  0.98 
E)  2.2

Question 20

The graphs below show a voltage phasor at different instances of time. The voltage phasor which shows the instantaneous value of the voltage with the largest magnitude is

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Exam 33: Alternating-Current Circuits

The impedance of the parallel RLC circuit shown is given by

Determine the impedance for the circuit. ​ ​

What is the average power dissipation in an RLC series circuit with R = 10Ω, L = 0.1 H, C = 10 μF when driven at resonance by a 100 V-rms source?

If the input to an RLC series circuit is V = Vm cos ωt, then the current in the circuit is

A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RL circuit with R = 10.0 Ω and L = 10.0 mH. The impedance is

A 10-μF capacitor in an LC circuit made entirely of superconducting materials (R = 0 Ω) is charged to 100 μC. Then a superconducting switch is closed. At t = 0 s, plate 1 is positively charged and plate 2 is negatively charged. At a later time, Vab = +10 V. At that time, Vdc is

A step-up transformer has an input voltage of 110 V (rms). There are 100 turns on the primary and 1500 on the secondary. What is the output voltage?

At what frequency will a 50.0-mH inductor have a reactance XL = 700Ω?

Determine the rms voltage drop across the resistor in the circuit.

In a typical transmission line, the current I is very small and the voltage V is very large. A unit length of line has resistance R. For a power line that supplies power to 10000 households, we can conclude that

Which of the following is true about a diode?

At what frequency will a 12-μF capacitor have a reactance XC = 300Ω?

A 230000 V-rms powerline carries an average power Pavg = 250 MW a distance of 200 km. If the total resistance of the cables is 10 ohms, what is the resistive power loss?

A series RLC circuit has an impedance of 120Ω and a resistance of 64Ω. What average power is delivered to this circuit when Vrms = 90 volts?

Whenever the alternating current frequency in a series RLC circuit is halved,

A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RC circuit with R = 10.0 Ω and C = 300 μF. The peak current in the circuit is

Capacitive reactance XC is given by

Determine the rms current for the circuit.

Calculate Vout/Vin for the circuit if R = 2.0 kΩ, C = 0.020 μF and V = 140V sin(50000t). ​ ​

The graphs below show a voltage phasor at different instances of time. The voltage phasor which shows the instantaneous value of the voltage with the largest magnitude is

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Filters

Determine the impedance for the circuit.

If the input to an RLC series circuit is V = V_m cos ωt, then the current in the circuit is

A 10-μF capacitor in an LC circuit made entirely of superconducting materials (R = 0 Ω) is charged to 100 μC. Then a superconducting switch is closed. At t = 0 s, plate 1 is positively charged and plate 2 is negatively charged. At a later time, V_ab = +10 V. At that time, V_dc is

At what frequency will a 50.0-mH inductor have a reactance X_L = 700Ω?

At what frequency will a 12-μF capacitor have a reactance X_C = 300Ω?

A 230000 V-rms powerline carries an average power P_avg = 250 MW a distance of 200 km. If the total resistance of the cables is 10 ohms, what is the resistive power loss?

A series RLC circuit has an impedance of 120Ω and a resistance of 64Ω. What average power is delivered to this circuit when V_rms = 90 volts?

Capacitive reactance X_C is given by

Calculate V_out/V_in for the circuit if R = 2.0 kΩ, C = 0.020 μF and V = 140V sin(50000t).