Deck 10: Rccircuits

Question 1

As the frequency applied to an RC circuit varies, both XC and resistance vary.

Answer 1

False

Question 2

A leaky capacitor can be equated as a capacitor with a resistor being placed in series with it.

Answer 2

False

Question 3

When the frequency applied to an RC circuit varies, the value of XC varies.

Answer 3

True

Question 4

As the frequency applied to an RC circuit is decreased, the phase angle decreases.

Question 5

If the operating frequency increases in Figure 10 -1, how does the resistor value change?

A)It remains the same.
B)It opens.
C)It decreases.
D)It increases.

Question 6

Power factor values close to 0 denotes an RC circuit with mostly true power.

Question 7

What is the circuit's impedance in Figure 10 -1?

A)520 Ω
B)418 Ω
C)280 Ω
D)120 Ω

Question 8

What is the true power in Figure 10 -1?

A)5.73 W
B)916 mW
C)275 mW
D)5.73 mW

Question 9

The total current in an RC circuit always lags the source voltage.

Question 10

As the frequency applied to an RC circuit increases, the impedance decreases.

Question 11

The phasor combination of XC and R is called Z.

Question 12

The phase angle of an RC circuit varies inversely with frequency.

Question 13

A high pass filter will cause some phase shifting of the signal.

Question 14

The phasor combination of VR and VC in an RC series circuit equals the source voltage.

Question 15

If the operating frequency increases in Figure 10 -1, how does the phase angle change?

A)It changes to another quadrant.
B)It increases.
C)It remains the name.
D)It decreases.

Question 16

If the operating frequency increases in Figure 10 -1, how does the current change?

A)It remains the same.
B)It increases.
C)It decreases.
D)It decreases to zero.

Question 17

A VA rating is more relevant when judging the current delivery capacity for a given signal source.

Question 18

If the frequency equals 60 Hz in Figure 10 -1, what is the value of capacitance?

A)88 µF
B)66 µF
C)22 µF
D)44 µF

Question 19

The total current in an RC circuit always leads the source voltage.

Question 20

An RC circuit can be used as a filter to eliminate selected frequencies.

Question 21

Which statement describes the relationship of IC and IR in Figure 10 -2?

A)They are in phase.
B)IC leads IR.
C)They are 180° out of phase.
D)IC lags IR.

Question 22

If the frequency decreases in Figure 10 -1, the phase angle and the impedance _.

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

Question 23

If the operating frequency decreases in Figure 10 -1, how does the resistance value change?

A)It decreases.
B)It increases.
C)It opens.
D)It remains the same.

Question 24

If the operating frequency decreases in Figure 10 -1, how does the current change?

A)It decreases.
B)It increases.
C)It remains the same.
D)It decreases to zero.

Question 25

How much voltage does the resistor drop in Figure 10 -2?

A)59 mV
B)19.94 V
C)20 V
D)10 V

Question 26

If the frequency is 400 Hz in Figure 10 -1, what is the value of capacitance?

A)10 µF
B)6.6 µF
C)8.8 µF
D)3.3 µF

Question 27

If the operating frequency decreases in Figure 10 -1, how does the capacitance value change?

A)It remains the same.
B)It decreases.
C)It increases.
D)It decreases to zero.

Question 28

If the source voltage is changed to 100 V in Figure 10 -1, find the true power.

A)3.66 W
B)22.9 W
C)11 W
D)22.9 mW

Question 29

What change would decrease the power factor in Figure 10 -2?

A)increasing the value of the resistor
B)increasing the value of Vs
C)decreasing the value of the capacitor
D)increasing the value of the capacitor

Question 30

If the resistor changes to 2.2 kΩ in Figure 10 -1, how does the total current change?

A)It decreases.
B)It decreases to zero.
C)It increases.
D)It remains the same.

Question 31

If the operating frequency decreases in Figure 10 -1, how does the phase angle change?

A)It decreases.
B)It increases.
C)It changes to another quadrant.
D)It remains the same.

Question 32

The circuit in Figure 10 -3 is known as a _ .

A)band -pass filter
B)high -pass filter
C)parallel RC circuit
D)low -pass filter

Question 33

Calculate the voltage drop across the capacitor in Figure 10 -1.

A)3.69 V
B)4.82 V
C)11.5 V
D)14.4 V

Question 34

If the resistor value increases in Figure 10 -2, then how does the total current change?

A)It decreases to zero.
B)It increases.
C)It decreases.
D)It remains the same.

Question 35

What change would increase the power factor in Figure 10 -2?

A)Increasing the value of the source voltage
B)Increasing the value of the capacitor
C)Decreasing the value of the capacitor
D)Increasing the value of the resistor

Question 36

Calculate the total impedance in Figure 10 -2.

A)880 Ω
B)1000 Ω
C)258 Ω
D)62 Ω

Question 37

How much voltage does the capacitor drop in Figure 10 -2?

A)59 mV
B)10 V
C)20 V
D)19.94 V

Question 38

Calculate the apparent power in Figure 10 -1.

A)5.66 VA
B)5.99 VA
C)14.37 VA
D)1.70 VA

Question 39

What is the cutoff frequency in Figure 10 -3?

A)1012 Hz
B)85 Hz
C)118 Hz
D)995 Hz

Question 40

If the frequency increases in Figure 10 -1, the phase angle and the impedance _.

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

Question 41

A power factor of 1 indicates that the circuit phase angle is .

A)90°
B)0°
C)180°
D)45°

Question 42

In a series RC circuit, as the phase angle between the applied voltage and the total current increases, this is the same as:

A)power factor increasing.
B)apparent power decreasing.
C)true power decreasing.
D)power factor decreasing.

Question 43

In an RC circuit, the capacitive reactance is:

A)decreases as the frequency increases.
B)inversely proportional to the capacitance.
C)inversely proportional to the frequency.
D)all of these.

Question 44

If the input voltage increases to 50 V in Figure 10 -3, what is the output voltage at the cutoff frequency?

A)35.4 V
B)17.7 V
C)70.7 V
D)8.84 V

Question 45

An RC lag network is similar to a:

A)high pass filter.
B)low pass filter.
C)stop pass filter.
D)band pass filter.

Question 46

What is the circuit fault in Figure 10 -3 if the output voltage equals 0 V at the cutoff frequency?

A)The capacitor has opened.
B)The capacitor has become leaky.
C)The capacitor has shorted.
D)The resistor has shorted.

Question 47

If the circuit in Figure 10 -3 has an output voltage that's too high at the cutoff frequency, .

A)the resistor has opened
B)the capacitor has become leaky
C)the capacitor has shorted
D)the resistor has shorted

Question 48

In a X10 oscilloscope probe input resistance is factor of 10. _ and input capacitance is
_ by a

A)increased, decreased
B)decreased, increased
C)decreased, decreased
D)increased, increased

Question 49

Power in an RC circuit can be measured as:

A)apparent power (Pa).
B)reactive power (Pr).
C)true power (Ptrue).
D)all of these.

Question 50

When an AC voltage is supplied to an RC circuit, the AC's current and amplitude will be:

A)leading the voltage.
B)varying in the same manner.
C)similar in waveform.
D)all of these.

Question 51

If the bandwidth of a low -pass filter is 0 to 1 kHz, the cutoff frequency is .

A)2 kHz
B)0 Hz
C)1 kHz
D)500 Hz

Question 52

If the resistor changes to 2.2 kΩ in Figure 10 -3, the new cutoff frequency equals .

A)1.18 kHz
B)995 Hz
C)1.81 kHz
D)1.01 kHz

Question 53

If there is 10 VRMS across the resistor and 10 VRMS across the capacitor in a series RC circuit, then the source voltage equals _.

A)20 VRMS
B)28.3 VRMS
C)10 VRMS
D)14.1 VRMS

Question 54

What is the output voltage at the cutoff frequency in Figure 10 -3?

A)31.1 V
B)6.45 V
C)15.6 V
D)22 V

Question 55

An RC high pass filter takes its output across:

A)the series resistor.
B)the parallel capacitor.
C)the series capacitor.
D)the parallel resistor.

Question 56

If the resistance is reduced to 4 kΩ in Figure 10 -3, the cutoff frequency equals .

A)480 Hz
B)6250 Hz
C)995 Hz
D)99 Hz

Question 57

If the resistor is changed to 100 kΩ in Figure 10 -3, what is the new cutoff frequency?

A)79.6 Hz
B)318 Hz
C)159 Hz
D)39.8 Hz

Question 58

If there is 1 ARMS through the resistor and 1 ARMS through the capacitor in a parallel RC circuit, then the total current equals .

A)2 ARMS
B)2.28 ARMS
C)1.41 ARMS
D)1 ARMS

Question 59

If the true power is 100 W and the reactive power is 100 VAR, the apparent power is .

A)141 VA
B)200 VA
C)141 W
D)100 VA

Question 60

If the output were taken across the resistor in Figure 10 -3, the circuit would be known as a .

A)low -pass filter
B)band -notch filter
C)band -pass filter
D)high -pass filter

Question 61

In an RC filter circuit, the cutoff frequency is defined as the frequency at which:

A)the output voltage drops to 33% of maximum.
B)the output voltage is cutoff, with minimum or zero output.
C)the output voltage drops to 66% of maximum.
D)the output voltage drops to 70% of maximum.

Question 62

Which of these troubleshooting procedures should be performed first?

A)Slap the device firmly to dislodge foreign objects.
B)Check test equipment connections.
C)Take random measurements around point of failure.
D)Analyze the problem and decide where best to start.

Question 63

It has been determined that the phase shift of a given parallel RC circuit is lower than predicted. Which of the following most likely has caused this?

A)Resistance has decreased.
B)The function generator frequency control has been accidentally moved to a lower frequency.
C)The capacitance has decreased.
D)could be A or C

Question 64

This frequency response curve in Figure 10 -4 represents what type of filter?

A)band pass
B)low pass
C)high pass
D)band stop

Question 65

Simple RC circuits can be viewed as what type of filter?

A)passive
B)low pass
C)active
D)high pass

Question 66

The output voltage of an RC high pass filter at a designated frequency is low. What is a possible problem?

A)shorted capacitor
B)open resistor
C)not enough information
D)function generator misadjusted