Question 1

A circuit with alternating current has its voltage and current in phase.How does the average power compare to the root mean square of the current and voltage?

Accepted Answer

Average po

Question 2

The 60 Hz ac source of a series circuit has a voltage amplitude of 120 V.The capacitive and inductive reactances are 980 Ω and 240 Ω,respectively.The resistance is 550 Ω.In the figure,the inductance,in mH,is closest to:

Accepted Answer

A) 640 
B) 1400 
C) 2400 
D) 3000 
E) 4000 
A) 640 
B) 1400 
C) 2400 
D) 3000 
E) 4000

Question 3

An RLC circuit has a reactance,due to its capacitance,of 11 kΩ;a reactance,due to its inductance,of 3 kΩ;and a resistance of 29 kΩ.What is the power factor of the circuit?

Accepted Answer

A) 0.96 
B) 0.27 
C) 1.04 
D) 0.48 
A) 0.96 
B) 0.27 
C) 1.04 
D) 0.48

Question 4

A circuit containing a 39-H inductor has an alternating current supplied to it.If Irms is 10.0 A and Vp is 18 V,find the frequency of the signal.

Accepted Answer

A) 0.0052 Hz 
B) 0.21 Hz 
C) 0.033 Hz 
D) 0.41 Hz 
A) 0.0052 Hz 
B) 0.21 Hz 
C) 0.033 Hz 
D) 0.41 Hz

Question 5

The 60 Hz ac source of a series circuit has a voltage amplitude of 120 V.The capacitive and inductive reactances are 780 Ω and 210 Ω.respectively.The resistance is 460 Ω.In the figure,the rms current in the circuit is closest to:

Accepted Answer

A) 0.12 A 
B) 0.13 A 
C) 0.14 A 
D) 0.16 A 
E) 0.18 A 
A) 0.12 A 
B) 0.13 A 
C) 0.14 A 
D) 0.16 A 
E) 0.18 A

Question 6

A series AC circuit is shown.The inductor has a reactance of 60 Ω and an inductance of 170 mH.A 80 Ω resistor and a capacitor whose reactance is 110 Ω are also in the circuit.The rms current in the circuit is 1.6 A.In the figure,the voltage amplitude across the capacitor is closest to:

Accepted Answer

A) 250 V 
B) 180 V 
C) 320 V 
D) 390 V 
E) 110 V 
A) 250 V 
B) 180 V 
C) 320 V 
D) 390 V 
E) 110 V

Question 7

A capacitor,initially having a charge Q on the left plate and a charge -Q on the right plate,is connected to a switch and an inductor,as shown below.The frequency in which the current will flow back and forth after the switch is closed will increase if

Accepted Answer

A) the inductance of the inductor is increased. 
B) the capacitance of the capacitor is increased. 
C) the initial charge of the capacitor is increased. 
D) More than one of the above 
E) None of the above 
A) the inductance of the inductor is increased. 
B) the capacitance of the capacitor is increased. 
C) the initial charge of the capacitor is increased. 
D) More than one of the above 
E) None of the above

Question 8

The inductor in a radio receiver carries a current of amplitude 200 mA when a voltage of amplitude 2.4 V is across it at a frequency of 1400 Hz.What is the value of the inductance?

Accepted Answer

A) 1.43 mH 
B) 1.36 mH 
C) 9.20 mH 
D) 4.42 mH 
E) 1.97 mH 
A) 1.43 mH 
B) 1.36 mH 
C) 9.20 mH 
D) 4.42 mH 
E) 1.97 mH

Question 9

What is the resonance frequency of an LC circuit consisting of a 26.0 μF capacitor and a 0.010 H inductor?

Accepted Answer

A) 0.31 kHz 
B) 2.0 kHz 
C) 3.2 kHz 
D) 12 kHz 
A) 0.31 kHz 
B) 2.0 kHz 
C) 3.2 kHz 
D) 12 kHz

Question 10

The reactance of a capacitor is 7.0 kΩ at a frequency of 0.30 kHz.What is the capacitance?

Accepted Answer

A) 0.076 μF 
B) 0.48 μF 
C) 3.0 μF 
D) 0.107 μF 
A) 0.076 μF 
B) 0.48 μF 
C) 3.0 μF 
D) 0.107 μF

Question 11

A series RLC circuit has a peak current of 1.0 A with a frequency of 66 kHz.If the resistance of the circuit is 51 kΩ the capacitance of the circuit is 13 μF,and the inductance of the circuit is 30 H,determine the average power of the circuit over one cycle.

Accepted Answer

A) 26,000 W 
B) 77,000 W 
C) 7700 W 
D) 4100 W 
A) 26,000 W 
B) 77,000 W 
C) 7700 W 
D) 4100 W

Question 12

The AC current through a capacitor lags the capacitor voltage by 90°.

Accepted Answer

A) True 
 B)False

Question 13

To find the resonant frequency of an RLC circuit,you could adjust the frequency of the AC source until the current reaches its minimum value.

Accepted Answer

A) True 
 B)False

Question 14

A step-up transformer lowers current but raises voltage.

Accepted Answer

A) True 
 B)False

Question 15

Just as a 100 Ω resistor always has the same resistance no matter what circuit it is in,likewise a 50 μF capacitor always has the same reactance no matter what circuit it is in.

Accepted Answer

A) True 
 B)False

Exam 26: Ac Electricity

A circuit with alternating current has its voltage and current in phase.How does the average power compare to the root mean square of the current and voltage?

The 60 Hz ac source of a series circuit has a voltage amplitude of 120 V.The capacitive and inductive reactances are 980 Ω and 240 Ω,respectively.The resistance is 550 Ω.In the figure,the inductance,in mH,is closest to:

An RLC circuit has a reactance,due to its capacitance,of 11 kΩ;a reactance,due to its inductance,of 3 kΩ;and a resistance of 29 kΩ.What is the power factor of the circuit?

A circuit containing a 39-H inductor has an alternating current supplied to it.If Irms is 10.0 A and Vp is 18 V,find the frequency of the signal.

The 60 Hz ac source of a series circuit has a voltage amplitude of 120 V.The capacitive and inductive reactances are 780 Ω and 210 Ω.respectively.The resistance is 460 Ω.In the figure,the rms current in the circuit is closest to:

A series AC circuit is shown.The inductor has a reactance of 60 Ω and an inductance of 170 mH.A 80 Ω resistor and a capacitor whose reactance is 110 Ω are also in the circuit.The rms current in the circuit is 1.6 A.In the figure,the voltage amplitude across the capacitor is closest to:

A capacitor,initially having a charge Q on the left plate and a charge -Q on the right plate,is connected to a switch and an inductor,as shown below.The frequency in which the current will flow back and forth after the switch is closed will increase if

The inductor in a radio receiver carries a current of amplitude 200 mA when a voltage of amplitude 2.4 V is across it at a frequency of 1400 Hz.What is the value of the inductance?

What is the resonance frequency of an LC circuit consisting of a 26.0 μF capacitor and a 0.010 H inductor?

The reactance of a capacitor is 7.0 kΩ at a frequency of 0.30 kHz.What is the capacitance?

A series RLC circuit has a peak current of 1.0 A with a frequency of 66 kHz.If the resistance of the circuit is 51 kΩ the capacitance of the circuit is 13 μF,and the inductance of the circuit is 30 H,determine the average power of the circuit over one cycle.

The AC current through a capacitor lags the capacitor voltage by 90°.

To find the resonant frequency of an RLC circuit,you could adjust the frequency of the AC source until the current reaches its minimum value.

A step-up transformer lowers current but raises voltage.

Just as a 100 Ω resistor always has the same resistance no matter what circuit it is in,likewise a 50 μF capacitor always has the same reactance no matter what circuit it is in.

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A circuit containing a 39-H inductor has an alternating current supplied to it.If I_rms is 10.0 A and V_p is 18 V,find the frequency of the signal.