Deck 10: Magnetism and Electromagnetism

Question 1

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

Answer 1

True

Question 2

The phasor combination of V in an RC series circuit equals the source voltage.

Answer 2

True

Question 3

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

Answer 3

True

Question 4

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

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

Question 5

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

Question 6

What is the true power in Figure 10-1?

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

Question 7

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

Question 8

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

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

Question 9

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

Question 10

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

Question 11

The phasor combination of and R is called Z.

Question 12

What is the circuitʹs impedance in Figure 10-1?

A)
B)
C)
D)

Question 13

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

Question 14

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

Question 15

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

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

Question 16

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

Question 17

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

Question 18

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

Question 19

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

Question 20

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

A)
B)
C)
D)

Question 21

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

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

Question 22

Calculate the apparent power in Figure 10-1.

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

Question 23

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

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

Question 24

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

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

Question 25

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

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

Question 26

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

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

Question 27

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

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

Question 28

Calculate the total impedance in Figure 10-2.

A)
B)
C)
D)

Question 29

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

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

Question 30

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

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

Question 31

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

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

Question 32

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

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

Question 33

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

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

Question 34

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

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

Question 35

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

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

Question 36

What is the cutoff frequency in Figure 10-3?

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

Question 37

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

A)
B)They are in phase.
C)
D)They are 180° out of phase.

Question 38

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

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

Question 39

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

A)
B)
C)
D)

Question 40

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

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

Question 41

An RC high pass filter takes its output across:

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

Question 42

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

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

Question 43

In an RC circuit, the capacitive reactance is:

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

Question 44

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

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

Question 45

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

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

Question 46

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

A)
B)
C)
D)

Question 47

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

A)
B)
C)
D)

Question 48

If the circuit in Figure 10-3 has an output voltage thatʹs too high at the cutoff frequency, ________.

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

Question 49

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

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

Question 50

Power in an RC circuit can be measured as:

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

Question 51

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

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

Question 52

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

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

Question 53

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

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

Question 54

An RC lag network is similar to a:

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

Question 55

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

A)the output voltage drops to 70% 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 33% of maximum.

Question 56

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

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

Question 57

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

A)90°
B)45°
C)0°
D)180°

Question 58

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

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

Question 59

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

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

Question 60

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

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

Question 61

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

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

Question 62

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 63

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

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

Question 64

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

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

Question 65

Which of these troubleshooting procedures should be performed first?

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