Deck 13: Inductors

Question 1

At resonance, equals .

Answer 1

True

Question 2

At resonance, a parallel RLC circuit is capacitive.

Answer 2

False

Question 3

As the frequency approaches the resonant frequency in Figure 13-1, the VR

A)becomes increasingly unstable
B)increases
C)remains the same
D)decreases

Answer 3

increases

Question 4

The capacitorʹs resistive effects are significant when considering the of an RLC circuit.

Question 5

At resonance, the impedance of a series RLC circuit equals its resistance.

Question 6

If frequency increases in Figure 13-1, the impedance ________ and the current ________.

A)decreases, decreases
B)increases, increases
C)decreases, increases
D)increases, decreases

Question 7

A series RLC circuit can be configured for band-pass or band-stop filtering purposes.

Question 8

In a resonant circuit, as Q increases the bandwidth decreases.

Question 9

A highly selective filter has a very wide bandwidth.

Question 10

The true power of an RLC circuit depends on the value of resistance.

Question 11

In a parallel resonant circuit, the impedance is minimum and the line current is maximum.

Question 12

At resonance, a series RLC circuit has maximum current.

Question 13

If the resistance increases in Figure 13-1, the impedance ________.

A)becomes zero
B)remains the same
C)increases
D)decreases

Question 14

A resonant RLC circuit is said to be very selective if its is very low.

Question 15

The total impedance equals the resistance of a resonant series RLC circuit.

Question 16

Current leads in a series RLC circuit with more capacitive reactance than inductive reactance.

Question 17

At resonance, a parallel RLC circuit is inductive.

Question 18

Find the voltage across the capacitor in Figure 13-1.

A)10.7 V
B)0.633 V
C)-4.9 V
D)5.37 V

Question 19

In a series resonant circuit, the impedance is minimum and the current is maximum.

Question 20

To operate the circuit in Figure 13-1 at resonance, ________ the resistance and ________ the frequency.

A)decrease, decrease
B)donʹt change, increase
C)increase, increase
D)donʹt change, decrease

Question 21

At resonance, the current in Figure 13-2 is ________.

A)1.66 mA
B)10 A
C)1.66 4
D)10 mA

Question 22

If the resistance decreases in Figure 13-1, the impedance ________.

A)decreases
B)becomes zero
C)remains the same
D)increases

Question 23

If the resistance decreases in Figure 13-2, the bandwidth ________.

A)decreases
B)varies
C)remains the same
D)increases

Question 24

If a tuned tank circuit has a very narrow bandwidth, its Q is probably ________.

A)very low
B)below 10
C)about 10
D)very high

Question 25

If an LC tank circuit is operating below resonance, the circuit is ________ in nature.

A)inductive
B)capacitive
C)positive
D)resistive

Question 26

If the resistor shorts in Figure 13-2, the current ________.

A)increases
B)continues, but the circuit would not be resonant
C)decreases
D)does not change

Question 27

If the capacitor opens in Figure 13-2, the current ________.

A)remains the same
B)increases because of the inductor
C)continues to flow, but the circuit would not be resonant
D)decreases to zero

Question 28

The resonant frequency of a tank circuit with a 0.150 mH inductor and 300 pF capacitor is ________.

A)1.65 MHz
B)750 kHz
C)6.05 MHz
D)347 kHz

Question 29

To operate the circuit in Figure 13-1 below the resonant frequency, ________ the resistance and ________ the frequency.

A)do not change, decrease
B)do not change, increase
C)decrease, decrease
D)increase, increase

Question 30

What is the bandwidth of a resonant circuit if its resonant frequency is 14.2 MHz, the inductive reactance is 3.5 kΩ and the coilʹs resistance is 8 ohm?

A)2285 Hz
B)32.5 kHz
C)14.2 MHz
D)28.4 kHz

Question 31

If a resonant circuit has a low Q, it ________.

A)has a small voltage across the capacitor
B)has a wide pass-band
C)tunes sharply
D)has a narrow pass-band

Question 32

What is the resonant frequency of a tank circuit with a 50 mH inductor and C = 256 pF capacitor?

A)44.5 kHz
B)44.5 Hz
C)445 kHz
D)4.45 kHz

Question 33

If the frequency decreases in Figure 13-1, the impedance initally ________ and the current initially ________.

A)decreases, increases
B)increases, increases
C)increases, decreases
D)decreases, decreases

Question 34

If the current is 0 A in Figure 13-2, maybe ________.

A)the capacitor is shorted
B)the resistor is open
C)
D)the inductor is shorted

Question 35

What is the current in a parallel RLC circuit if its impedance is is 100 and VS = 50 V?

A)2.27 mA
B)0.0227 mA
C)22.7 mA
D)0.227 mA

Question 36

In a parallel resonant RLC circuit, the impedance is ________ and the total current is ________.

A)maximum. maximum
B)minimum, minimum
C)minimum, maximum
D)maximum, minimum

Question 37

If the frequency decreases in Figure 13-1, the impedance ________ and the phase angle ________.

A)increases, increases
B)decreases, decreases
C)decreases, increases
D)increases, decreases

Question 38

What is the of an RLC series resonant circuit with the output across the inductor if the resonant frequency is 14 MHz, the source voltage is 12 V and the inductor drops 300 V?

A)13.98 dB
B)25 dB
C)42.91 dB
D)27.96 dB

Question 39

What is the power at in a resonant circuit that delivers 120 W?

A)
B)84.8 W
C)60 W
D)17 W at both frequencies

Question 40

If the resistance increases in Figure 13-2, the bandwidth ________.

A)increases
B)remains the same
C)varies
D)decreases

Question 41

Replacing the inductor in a series resonant band-pass filter with one having a lower Q value causes the bandwidth to ________.

A)increase
B)remain the same
C)be more selective
D)decrease

Question 42

If a tank circuit is operating above resonance, it is ________ in nature.

A)inductive
B)positive
C)capacitive
D)resistive

Question 43

In a series RLC circuit at resonance:

A)the impedance is mostly resistive.
B) equals and they cancel.
C)the impedance Z is at minimum.
D)all of these.

Question 44

What is the source voltage in a series resonant circuit if

A)300 V
B)50 V
C)350 V
D)150 V

Question 45

What is the ratio of in an RLC series resonant circuit if the output voltage is taken across the inductor, the resonant frequency is 14 MHz, the source voltage is 18 V
And the inductor drops 300 V?

A)28 dB
B)24.4 dB
C)14.0 dB
D)42.9 dB

Question 46

If a tuned tank circuit has a very wide bandwidth, its might be ________.

A)about 10
B)about 100
C)very high
D)very low

Question 47

The total reactance of a series RLC circuit at resonance is ________.

A)infinity
B)equal to the resistance
C)capacitive
D)zero

Question 48

What is the resonant frequency of a tank circuit with a 150 mH inductor and a 300 pF capacitor?

A)23.7 kHz
B)237 kHz
C)23.7 Hz
D)2.37 MHz

Question 49

What is the power at and in a resonant circuit that delivers 750 W?

A)375 W at both frequencies
B)750 W at both frequencies
C) and 750 W at
D)17 W at both frequencies

Question 50

In a parallel RLC circuit,at resonance the capacitive reactance (XC) and the inductive reactance (XL):

A)are moderate.
B)equal and oppose current flow.
C)are minimum.
D)add to each to cancel current flow.

Question 51

What is the total current in a parallel resonant circuit if its impedance is is 100 and the source voltage is 100 V?

A)4.55 mA
B)0.0455 mA
C)45.5 mA
D)0.455 mA

Question 52

If the resonant frequency is 1 MHz and Q

A)0.98 MHz, 1.01 MHz
B)0.98 MHz, 1.02 MHz
C)0.99 MHz, 1.02 MHz
D)0.99 MHz, 1.01 MHz

Question 53

In a series RLC circuit just above the resonant frequency, the impedance is:

A)more inductive.
B)more capacitive.
C)at maximum.
D)at minimum.

Question 54

What is the resonant impedance of a series RLC circuit with a 15 mH inductor, 0.015 capacitor and 80 resistor?

A)
B)
C)
D)

Question 55

In a series RLC circuit just below the resonant frequency, the impedance is:

A)more inductive.
B)at maximum.
C)more capacitive.
D)at minimum.

Question 56

In a series RLC circuit at resonance, the capacitive reactance and the inductive reactance :

A)add to each other.
B)cancel each other.
C)are minimum.
D)are moderate.

Question 57

A resonant circuit with a high

A)has a very wide pass-band
B)has no pass-band
C)tunes sharply
D)has a small voltage across the capacitor

Question 58

In an ideal parallel resonant circuit, the total current into the L and C branches is ________.

A)high
B)zero
C)low
D)maximum

Question 59

What is the lower cut off frequency in an RLC resonant circuit if the inductive reactance is , the resonant frequency is 22 kHz and the resistance is

A)21.7 kHz
B)21.8 kHz
C)21.5 kHz
D)20.9 kHz

Question 60

What is the bandwidth of the resonant circuit if the resonant frequency is 1.42 MHz, the inductive reactance is and the coilʹs resistance is 8 ohm?

A)32.5 kHz
B)3.25 kHz
C)1.42 MHz
D)2285 Hz

Question 61

The output voltage of a circuit at 70.7% of its maximum level measured in dB is:

A)-3 dB.
B)-7 db.
C)7 dB.
D)3 dB.

Question 62

In a parallel RLC circuit just above the resonant frequency, the impedance is:

A)at minimum.
B)at maximum.
C)more capacitive.
D)more inductive.

Question 63

The selectivity of a given band-pass filter has degraded significantly, yet the fr is within tolerance. Which of the following could have caused this?

A)The inductance has increased.
B)The load has opened.
C)The capacitance has increased.
D)none of the above

Question 64

Why does a resistive load increase the bandwidth of a given band-pass filter?

A)A resistive load actually decreases the bandwidth.
B)The resistance decreases the quality of the circuit.
C)The resistance increases the quality of the circuit.
D)not enough information

Question 65

For the tuning circuit of a radio frequency receiver, the filter:

A)high Q components are not necessary.
B)bandwidth should be narrow.
C)need not be highly selective.
D)any of the above

Question 66

Which statement best describes the phase angle of a parallel RLC circuit at resonance?

A)With a net reactance at maximum the phase angle is zero.
B)With a net reactance at minimum the phase angle is zero.
C)Total current flow is minimum.
D)either A or C

Question 67

When tuning across the resonant frequency of a series RLC band-pass filter, which of the following is true?

A)The impedance of the filter should be minimum at resonance.
B)Current flow through the load is minimum.
C)The output voltage across the load is minimum.
D)The impedance of the filter should be maximum at resonance.

Question 68

Between the lower and upper critical frequencies of a band-pass filter:

A)the frequencies pass a maximum level.
B)the frequencies pass at 70% to their maximum levels.
C)the frequencies pass a minimum level.
D)the frequencies pass at 30% to their maximum levels.

Question 69

In a parallel RLC just below the resonant frequency, the impedance is:

A)more capacitive.
B)at maximum.
C)more inductive.
D)at minimum.