Question 1

The ideal meters shown read rms current and voltage.The average power delivered to the load is:

Accepted Answer

A) definitely not equal to VI 
B) perhaps more than VI 
C) possibly equal to VI even if the load contains an inductor and a capacitor 
D) definitely less than VI 
E) zero as is the average of any sine wave 
A) definitely not equal to VI 
B) perhaps more than VI 
C) possibly equal to VI even if the load contains an inductor and a capacitor 
D) definitely less than VI 
E) zero as is the average of any sine wave

Question 2

The rms value of an ac current is:

Accepted Answer

A) its peak value 
B) its average value 
C) that steady current that produces the same rate of heating in a resistor 
D) that steady current that will charge a battery at the same rate 
E) zero 
A) its peak value 
B) its average value 
C) that steady current that produces the same rate of heating in a resistor 
D) that steady current that will charge a battery at the same rate 
E) zero

Question 3

An RLC circuit has a capacitance of 12 $\mu$F, an inductance of 25 mH, and a resistance of 60 $\Omega$.The current oscillates with an angular frequency of:

Accepted Answer

A) 1.2 *103 rad/s 
B) 1.4 *103 rad/s 
C) 1.8 *103 rad/s 
D) 2.2 * 103 rad/s 
E) 2.6 *103 rad/s 
A) 1.2 *103 rad/s 
B) 1.4 *103 rad/s 
C) 1.8 *103 rad/s 
D) 2.2 * 103 rad/s 
E) 2.6 *103 rad/s

Question 4

The total energy in an LC circuit is 5.0 *10-6 J.If L = 25 mH the maximum current is:

Accepted Answer

A) 10 mA 
B) 14 mA 
C) 20 mA 
D) 28 mA 
E) 40 mA 
A) 10 mA 
B) 14 mA 
C) 20 mA 
D) 28 mA 
E) 40 mA

Question 5

The primary of an ideal transformer has 100 turns and the secondary has 600 turns.Then:

Accepted Answer

A) the power in the primary circuit is less than that in the secondary circuit 
B) the currents in the two circuits are the same 
C) the voltages in the two circuits are the same 
D) the primary current is six times the secondary current 
E) the frequency in the secondary circuit is six times that in the primary circuit 
A) the power in the primary circuit is less than that in the secondary circuit 
B) the currents in the two circuits are the same 
C) the voltages in the two circuits are the same 
D) the primary current is six times the secondary current 
E) the frequency in the secondary circuit is six times that in the primary circuit

Question 6

When the frequency of the oscillator in a series RLC circuit is doubled:

Accepted Answer

A) the capacitive reactance is doubled 
B) the capacitive reactance is halved 
C) the impedance is doubled 
D) the current amplitude is doubled 
E) the current amplitude is halved 
A) the capacitive reactance is doubled 
B) the capacitive reactance is halved 
C) the impedance is doubled 
D) the current amplitude is doubled 
E) the current amplitude is halved

Question 7

The angular frequency of a certain RLC series circuit is $ \omega $0.A source of sinusoidal emf, with angular frequency 2$ \omega $0, is inserted into the circuit.After transients die out the angular frequency of the current oscillations is:

Accepted Answer

A) "$ \omega $0/2" 
B) "$ \omega $0" 
C) "1.5$ \omega $0 " 
D) "2$ \omega $0" 
E) "3$ \omega $0" 
A) "$ \omega $0/2" 
B) "$ \omega $0" 
C) "1.5$ \omega $0 " 
D) "2$ \omega $0" 
E) "3$ \omega $0"

Question 8

In a purely inductive circuit, the current lags the voltage by:

Accepted Answer

A) 0 (they are in phase) 
B) one-fourth of a cycle 
C) one-half of a cycle 
D) three-fourths of a cycle 
E) one cycle 
A) 0 (they are in phase) 
B) one-fourth of a cycle 
C) one-half of a cycle 
D) three-fourths of a cycle 
E) one cycle

Question 9

An LC circuit has an oscillation frequency of 105 Hz.If C = 0.1 $\mu$F, then L must be about:

Accepted Answer

A) 10 mH 
B) 1 mH 
C) 25 $\mu$H 
D) 2.5 $\mu$H 
E) 1 pH 
A) 10 mH 
B) 1 mH 
C) 25 $\mu$H 
D) 2.5 $\mu$H 
E) 1 pH

Question 10

The total energy in an LC circuit is 5.0 *10-6 J.If C = 15 $\mu$F the maximum charge on the capacitor is:

Accepted Answer

A) 0.82$\mu$C 
B) 8.5$\mu$C 
C) 12 $\mu$C 
D) 17 $\mu$C 
E) 24 $\mu$C 
A) 0.82$\mu$C 
B) 8.5$\mu$C 
C) 12 $\mu$C 
D) 17 $\mu$C 
E) 24 $\mu$C

Question 11

In the circuit shown, switch S is first pushed up to charge the capacitor.When S is then pushed down, the current in the circuit will oscillate at a frequency of:

Accepted Answer

A) 0.010 Hz 
B) 12.5 Hz 
C) 320 Hz 
D) 2000 Hz 
E) depends on V0 
A) 0.010 Hz 
B) 12.5 Hz 
C) 320 Hz 
D) 2000 Hz 
E) depends on V0

Question 12

An RLC series circuit is connected to an oscillator with a maximum emf of 100 V.If the voltage amplitudes VR, VL, and VC are all equal to each other, then VR must be:

Accepted Answer

A) 33 V 
B) 50 V 
C) 67 V 
D) 87 V 
E) 100 V 
A) 33 V 
B) 50 V 
C) 67 V 
D) 87 V 
E) 100 V

Question 13

In an ideal 1:8 step-down transformer, the primary power is 10 kW and the secondary current is 25 A.The primary voltage is:

Accepted Answer

A) 25,600 V 
B) 3200 V 
C) 400 V 
D) 50 V 
E) 6.25 V 
A) 25,600 V 
B) 3200 V 
C) 400 V 
D) 50 V 
E) 6.25 V

Question 14

A 150-g block on the end of a spring with a spring constant of 35 N/m is pulled aside 25 cm and released from rest.In the electrical analog the initial charge on the capacitor is:

Accepted Answer

A) 0.15 C 
B) 0.25 C 
C) 8.8 C 
D) 15 C 
E) 35 C 
A) 0.15 C 
B) 0.25 C 
C) 8.8 C 
D) 15 C 
E) 35 C

Question 15

The resistance of the primary coil of a well-designed, 1:10 step-down transformer is 1$\Omega$.With the secondary circuit open, the primary is connected to a 12 V ac generator.The primary current is:

Accepted Answer

A) essentially zero 
B) about 12 A 
C) about 120 A 
D) depends on the actual number of turns in the primary coil 
E) depends on the core material 
A) essentially zero 
B) about 12 A 
C) about 120 A 
D) depends on the actual number of turns in the primary coil 
E) depends on the core material

Question 16

In a purely capacitive circuit the current:

Accepted Answer

A) leads the voltage by one-fourth of a cycle 
B) leads the voltage by one-half of a cycle 
C) lags the voltage by one-fourth of a cycle 
D) lags the voltage by one-half of a cycle 
E) is in phase with the potential difference across the plates 
A) leads the voltage by one-fourth of a cycle 
B) leads the voltage by one-half of a cycle 
C) lags the voltage by one-fourth of a cycle 
D) lags the voltage by one-half of a cycle 
E) is in phase with the potential difference across the plates

Question 17

An RL series circuit is connected to an ac generator with a maximum emf of 20 V.If the maximum potential difference across the resistor is 16 V, then the maximum potential difference across the inductor is:

Accepted Answer

A) 2 V 
B) 4 V 
C) 12 V 
D) 26 V 
E) 36 V 
A) 2 V 
B) 4 V 
C) 12 V 
D) 26 V 
E) 36 V

Question 18

The units of the power factor are:

Accepted Answer

A) ohm 
B) watt 
C) radian 
D) ohm1/2 
E) none of these 
A) ohm 
B) watt 
C) radian 
D) ohm1/2 
E) none of these

Question 19

A capacitor in an LC oscillator has a maximum potential difference of 15 V and a maximum energy of 360 $\mu$J.At a certain instant the energy in the capacitor is 40 $\mu$J.At that instant what is the emf induced in the inductor?

Accepted Answer

A) 0 V 
B) 5 V 
C) 10 V 
D) 15 V 
E) 20 V 
A) 0 V 
B) 5 V 
C) 10 V 
D) 15 V 
E) 20 V

Question 20

The electrical analog of a spring constant k is:

Accepted Answer

A) L 
B) 1/L 
C) C 
D) 1/C 
E) R 
A) L 
B) 1/L 
C) C 
D) 1/C 
E) R

Exam 31: Electromagnetic Oscillations and Alternating Current

The ideal meters shown read rms current and voltage.The average power delivered to the load is:

The rms value of an ac current is:

An RLC circuit has a capacitance of 12 μ\muμ F, an inductance of 25 mH, and a resistance of 60 Ω\OmegaΩ .The current oscillates with an angular frequency of:

The total energy in an LC circuit is 5.0 *10-6 J.If L = 25 mH the maximum current is:

The primary of an ideal transformer has 100 turns and the secondary has 600 turns.Then:

When the frequency of the oscillator in a series RLC circuit is doubled:

The angular frequency of a certain RLC series circuit is ω \omega ω 0.A source of sinusoidal emf, with angular frequency 2 ω \omega ω 0, is inserted into the circuit.After transients die out the angular frequency of the current oscillations is:

In a purely inductive circuit, the current lags the voltage by:

An LC circuit has an oscillation frequency of 105 Hz.If C = 0.1 μ\muμ F, then L must be about:

The total energy in an LC circuit is 5.0 *10-6 J.If C = 15 μ\muμ F the maximum charge on the capacitor is:

In the circuit shown, switch S is first pushed up to charge the capacitor.When S is then pushed down, the current in the circuit will oscillate at a frequency of:

An RLC series circuit is connected to an oscillator with a maximum emf of 100 V.If the voltage amplitudes VR, VL, and VC are all equal to each other, then VR must be:

In an ideal 1:8 step-down transformer, the primary power is 10 kW and the secondary current is 25 A.The primary voltage is:

A 150-g block on the end of a spring with a spring constant of 35 N/m is pulled aside 25 cm and released from rest.In the electrical analog the initial charge on the capacitor is:

The resistance of the primary coil of a well-designed, 1:10 step-down transformer is 1 Ω\OmegaΩ .With the secondary circuit open, the primary is connected to a 12 V ac generator.The primary current is:

In a purely capacitive circuit the current:

An RL series circuit is connected to an ac generator with a maximum emf of 20 V.If the maximum potential difference across the resistor is 16 V, then the maximum potential difference across the inductor is:

The units of the power factor are:

A capacitor in an LC oscillator has a maximum potential difference of 15 V and a maximum energy of 360 μ\muμ J.At a certain instant the energy in the capacitor is 40 μ\muμ J.At that instant what is the emf induced in the inductor?

The electrical analog of a spring constant k is:

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Filters

An RLC circuit has a capacitance of 12 $\mu$ F, an inductance of 25 mH, and a resistance of 60 $\Omega$ .The current oscillates with an angular frequency of:

The total energy in an LC circuit is 5.0 *10^-6 J.If L = 25 mH the maximum current is:

The angular frequency of a certain RLC series circuit is $\omega$ ₀.A source of sinusoidal emf, with angular frequency 2 $\omega$ ₀, is inserted into the circuit.After transients die out the angular frequency of the current oscillations is:

An LC circuit has an oscillation frequency of 10⁵ Hz.If C = 0.1 $\mu$ F, then L must be about:

The total energy in an LC circuit is 5.0 *10^-6 J.If C = 15 $\mu$ F the maximum charge on the capacitor is:

An RLC series circuit is connected to an oscillator with a maximum emf of 100 V.If the voltage amplitudes V_R, V_L, and V_C are all equal to each other, then V_R must be:

The resistance of the primary coil of a well-designed, 1:10 step-down transformer is 1 $\Omega$ .With the secondary circuit open, the primary is connected to a 12 V ac generator.The primary current is:

A capacitor in an LC oscillator has a maximum potential difference of 15 V and a maximum energy of 360 $\mu$ J.At a certain instant the energy in the capacitor is 40 $\mu$ J.At that instant what is the emf induced in the inductor?