Question 1

A lightbulb is connected to a 120 V(rms),60 Hz source.How many times per second does the current reverse directions?

Accepted Answer

A)  60 
B)  130 
C)  120 
D)  30 
A)  60 
B)  130 
C)  120 
D)  30

Question 2

What is the capacitive reactance of an 8.00 $\mu$F V capacitor attached to 120 V rms at 60.0 Hz?

Accepted Answer

A)  166 $\Omega$ 
B)  332 $\Omega$ 
C)  663 $\Omega$ 
D)  480 $\Omega$ 
E)  960 $\Omega$ 
A)  166 $\Omega$ 
B)  332 $\Omega$ 
C)  663 $\Omega$ 
D)  480 $\Omega$ 
E)  960 $\Omega$

Question 3

As the ac frequency in an RLC circuit is increased to very high values,which of the contributions to the impedance dominates?

Accepted Answer

A)  the capacitive reactance 
B)  the inductive reactance 
C)  the resistance 
D)  the combined capacitive reactance and the resistance 
E)  More information is needed. 
A)  the capacitive reactance 
B)  the inductive reactance 
C)  the resistance 
D)  the combined capacitive reactance and the resistance 
E)  More information is needed.

Question 4

What is the rms current for an 8.0 $\mu$F capacitor attached to a 120 V rms 60 Hz source?

Accepted Answer

A)  2.8 A 
B)  1.4 A 
C)  0.72 A 
D)  0.36 A 
E)  0.18 A 
A)  2.8 A 
B)  1.4 A 
C)  0.72 A 
D)  0.36 A 
E)  0.18 A

Question 5

The power factor of an RLC series circuit _______ at resonance.

Accepted Answer

A)  is one 
B)  has a value that depends upon the ratio of inductive reactance to impedance 
C)  has a value that depends upon the ratio of capacitive reactance to impedance 
D)  is zero 
A)  is one 
B)  has a value that depends upon the ratio of inductive reactance to impedance 
C)  has a value that depends upon the ratio of capacitive reactance to impedance 
D)  is zero

Question 6

An ideal diode in an ac circuit

Accepted Answer

A)  doubles the current. 
B)  halves the current. 
C)  permits the current to flow in only one direction. 
D)  permits the current to flow in one direction and double the current to flow in the other. 
E)  permits the current to flow in one direction and half the current to flow in the other. 
A)  doubles the current. 
B)  halves the current. 
C)  permits the current to flow in only one direction. 
D)  permits the current to flow in one direction and double the current to flow in the other. 
E)  permits the current to flow in one direction and half the current to flow in the other.

Question 7

In a series LRC circuit the rms voltage across the resistor is 80 V,across the capacitor is 120 V,and across the inductor is 60 V.What is the phase constant for this circuit?

Accepted Answer

A)  27$^{\circ}$ 
B)  -27$^{\circ}$ 
C)  37$^{\circ}$ 
D)  -37$^{\circ}$ 
E)  -41$^{\circ}$ 
A)  27$^{\circ}$ 
B)  -27$^{\circ}$ 
C)  37$^{\circ}$ 
D)  -37$^{\circ}$ 
E)  -41$^{\circ}$

Question 8

If an AC circuit consists of a 220 mH inductor in series with a 25 pF capacitor and an AC generator with rms voltage of 12 V.If the frequency of the generator is 55 kHz,what will the rms voltage drop across the capacitor be?

Accepted Answer

A)  5.4 V 
B)  0.20 V 
C)  6.6 V 
D)  11.80 V 
A)  5.4 V 
B)  0.20 V 
C)  6.6 V 
D)  11.80 V

Question 9

An RLC series circuit has a 400 $\Omega$ resistance,a 2.50 mH inductor,and a capacitor.If the circuit is in resonance at 30.0 kHz and is attached to a 20 mV rms power supply,what is the rms current?

Accepted Answer

A)  60 $\mu$A 
B)  40 $\mu$A 
C)  30 $\mu$A 
D)  50 $\mu$A 
E)  25 $\mu$A 
A)  60 $\mu$A 
B)  40 $\mu$A 
C)  30 $\mu$A 
D)  50 $\mu$A 
E)  25 $\mu$A

Question 10

In an ac circuit,the current in a capacitor

Accepted Answer

A)  leads the voltage by 90$\circ$. 
B)  lags the voltage by 90$\circ$. 
C)  is in phase with the voltage. 
D)  leads the voltage by $\pi$radians. 
E)  lags the voltage by $\pi$ radians. 
A)  leads the voltage by 90$\circ$. 
B)  lags the voltage by 90$\circ$. 
C)  is in phase with the voltage. 
D)  leads the voltage by $\pi$radians. 
E)  lags the voltage by $\pi$ radians.

Question 11

What is maximum number 150 W light bulbs that can run on a 130 V circuit protected by a 20 amp circuit breaker?

Accepted Answer

A)  18 
B)  16 
C)  17 
D)  15 
A)  18 
B)  16 
C)  17 
D)  15

Question 12

At what frequency is the reactance of a 20.0 mH inductor equal to 18.8 $\Omega$.

Accepted Answer

A)  75.0 Hz 
B)  150 Hz 
C)  1500 Hz 
D)  15.0 Hz 
A)  75.0 Hz 
B)  150 Hz 
C)  1500 Hz 
D)  15.0 Hz

Question 13

A 2.2 k $\Omega$ resistor and a 2.0 $\mu$F capacitor are in series in an ac circuit.The rms voltages across each are equal.What is the frequency?

Accepted Answer

A)  23 Hz 
B)  15 Hz 
C)  72 Hz 
D)  36 Hz 
E)  There is insufficient information to solve. 
A)  23 Hz 
B)  15 Hz 
C)  72 Hz 
D)  36 Hz 
E)  There is insufficient information to solve.

Question 14

The inductive reactance of an RLC circuit is 36 $\Omega$.If the frequency is doubled,what is the new inductive reactance?

Accepted Answer

A)  72 $\Omega$ 
B)  36 $\Omega$ 
C)  19 $\Omega$ 
D)  6.0 $\Omega$ 
E)  3.0 $\Omega$ 
A)  72 $\Omega$ 
B)  36 $\Omega$ 
C)  19 $\Omega$ 
D)  6.0 $\Omega$ 
E)  3.0 $\Omega$

Question 15

In a series LRC circuit the rms voltage across the resistor is 80.0 V,across the capacitor is 120 V,and across the inductor is 60.0 V.What is the rms voltage applied to this circuit?

Accepted Answer

A)  60.0 V 
B)  80.0 V 
C)  100 V 
D)  120 V 
E)  140 V 
A)  60.0 V 
B)  80.0 V 
C)  100 V 
D)  120 V 
E)  140 V

Question 16

What inductance is needed in series with a 4.7 $\mu$F capacitor for a resonant frequency of 10 kHz?

Accepted Answer

A)  22 uH 
B)  54 uH 
C)  0.66 uH 
D)  5.3 mH 
A)  22 uH 
B)  54 uH 
C)  0.66 uH 
D)  5.3 mH

Question 17

A series LR circuit dissipates 60 W.The circuit is powered by a 120 V rms 60 Hz supply.If the current is 2.0 A rms,what is the inductance?

Accepted Answer

A)  0.10 H 
B)  0.15 H 
C)  0.20 H 
D)  0.25 H 
E)  0.30 H 
A)  0.10 H 
B)  0.15 H 
C)  0.20 H 
D)  0.25 H 
E)  0.30 H

Question 18

The difference between the highest and lowest voltage of a household "120 V emf" is

Accepted Answer

A)  120 V. 
B)  170 V. 
C)  240 V. 
D)  340 V. 
E)  377 V. 
A)  120 V. 
B)  170 V. 
C)  240 V. 
D)  340 V. 
E)  377 V.

Question 19

A series RLC ac circuit has a capacitive reactance of 55 $\Omega$,and inductive reactance of 25 $\Omega$,and a resistance of 40 $\Omega$.What is the impedance of this circuit?

Accepted Answer

A)  12 $\Omega$ 
B)  95 $\Omega$ 
C)  70 $\Omega$ 
D)  10 $\Omega$ 
E)  50 $\Omega$ 
A)  12 $\Omega$ 
B)  95 $\Omega$ 
C)  70 $\Omega$ 
D)  10 $\Omega$ 
E)  50 $\Omega$

Question 20

A series RLC circuit has R = 200 $\Omega$, L = 40.0 mH, and C = 120 pF.What is the impedance of this circuit at resonance?

Accepted Answer

A)  18.0 k$\Omega$ 
B)  36.0 k$\Omega$ 
C)  400 $\Omega$ 
D)  300 $\Omega$ 
E)  200 $\Omega$ 
A)  18.0 k$\Omega$ 
B)  36.0 k$\Omega$ 
C)  400 $\Omega$ 
D)  300 $\Omega$ 
E)  200 $\Omega$

Exam 21: Alternating Current

A lightbulb is connected to a 120 V(rms),60 Hz source.How many times per second does the current reverse directions?

What is the capacitive reactance of an 8.00 μ\muμ F V capacitor attached to 120 V rms at 60.0 Hz?

As the ac frequency in an RLC circuit is increased to very high values,which of the contributions to the impedance dominates?

What is the rms current for an 8.0 μ\muμ F capacitor attached to a 120 V rms 60 Hz source?

The power factor of an RLC series circuit _______ at resonance.

An ideal diode in an ac circuit

In a series LRC circuit the rms voltage across the resistor is 80 V,across the capacitor is 120 V,and across the inductor is 60 V.What is the phase constant for this circuit?

If an AC circuit consists of a 220 mH inductor in series with a 25 pF capacitor and an AC generator with rms voltage of 12 V.If the frequency of the generator is 55 kHz,what will the rms voltage drop across the capacitor be?

An RLC series circuit has a 400 Ω\OmegaΩ resistance,a 2.50 mH inductor,and a capacitor.If the circuit is in resonance at 30.0 kHz and is attached to a 20 mV rms power supply,what is the rms current?

In an ac circuit,the current in a capacitor

What is maximum number 150 W light bulbs that can run on a 130 V circuit protected by a 20 amp circuit breaker?

At what frequency is the reactance of a 20.0 mH inductor equal to 18.8 Ω\OmegaΩ .

A 2.2 k Ω\OmegaΩ resistor and a 2.0 μ\muμ F capacitor are in series in an ac circuit.The rms voltages across each are equal.What is the frequency?

The inductive reactance of an RLC circuit is 36 Ω\OmegaΩ .If the frequency is doubled,what is the new inductive reactance?

In a series LRC circuit the rms voltage across the resistor is 80.0 V,across the capacitor is 120 V,and across the inductor is 60.0 V.What is the rms voltage applied to this circuit?

What inductance is needed in series with a 4.7 μ\muμ F capacitor for a resonant frequency of 10 kHz?

A series LR circuit dissipates 60 W.The circuit is powered by a 120 V rms 60 Hz supply.If the current is 2.0 A rms,what is the inductance?

The difference between the highest and lowest voltage of a household "120 V emf" is

A series RLC ac circuit has a capacitive reactance of 55 Ω\OmegaΩ ,and inductive reactance of 25 Ω\OmegaΩ ,and a resistance of 40 Ω\OmegaΩ .What is the impedance of this circuit?

A series RLC circuit has R = 200 Ω\OmegaΩ , L = 40.0 mH, and C = 120 pF.What is the impedance of this circuit at resonance?

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Filters

What is the capacitive reactance of an 8.00 $\mu$ F V capacitor attached to 120 V rms at 60.0 Hz?

What is the rms current for an 8.0 $\mu$ F capacitor attached to a 120 V rms 60 Hz source?

An RLC series circuit has a 400 $\Omega$ resistance,a 2.50 mH inductor,and a capacitor.If the circuit is in resonance at 30.0 kHz and is attached to a 20 mV rms power supply,what is the rms current?

At what frequency is the reactance of a 20.0 mH inductor equal to 18.8 $\Omega$ .

A 2.2 k $\Omega$ resistor and a 2.0 $\mu$ F capacitor are in series in an ac circuit.The rms voltages across each are equal.What is the frequency?

The inductive reactance of an RLC circuit is 36 $\Omega$ .If the frequency is doubled,what is the new inductive reactance?

What inductance is needed in series with a 4.7 $\mu$ F capacitor for a resonant frequency of 10 kHz?

A series RLC ac circuit has a capacitive reactance of 55 $\Omega$ ,and inductive reactance of 25 $\Omega$ ,and a resistance of 40 $\Omega$ .What is the impedance of this circuit?

A series RLC circuit has R = 200 $\Omega$ , L = 40.0 mH, and C = 120 pF.What is the impedance of this circuit at resonance?