Deck 18: Passive Filters

Question 1

The range of low frequencies passed by a low-pass filter within a specified limit is called the stopband.

Answer 1

False

Question 2

Figure 18-1
The capacitive reactance in Figure 18-1 is equal to the resistance at the critical frequency.

Answer 2

True

Question 3

The output voltage, in Figure 18-1 is how many dB down from the input voltage, at the critical frequency?

A) -0.707 dB
B) -20 dB
C) -3 dB
D) 0 dB

Answer 3

-3 dB

Question 4

The circuit in Figure 18-1 is:

A) a low-pass filter
B) a band-stop filter
C) a high-pass filter
D) a band-pass filter

Question 5

The circuit in Figure 18-1 has a critical frequency of:

A) 3.18 kHz
B) 31.8 kHz
C) 3.18 MHz
D) 318 kHz

Question 6

What is the output voltage, in Figure 18-3 at a frequency of 1.0 kHz?

A) 0.269 V
B) 4.90 V
C) 1.76 V
D) 3.45 V

Question 7

The phase shift of the circuit in Figure 18-1, at the critical frequency is:

A) 45°
B) 90°
C) 0°
D) 60.254°

Question 8

Frequency response is a graph of voltage gain versus frequency.

Question 9

Figure 18-3
The filter in Figure 18-3 has a Roll-off of:

A) -3 dB per decade
B) -20 dB per decade
C) -40 dB per decade
D) -6 dB per decade

Question 10

At the cutoff frequency, the voltage gain is 63.6% of the maximum.

Question 11

What is the output voltage, in Figure 18-1 at a frequency of 50 kHz?

A) 3.17 V
B) 1.76 V
C) 4.22 V
D) 3.45 V

Question 12

The phase shift of the circuit in Figure 18-3, at the critical frequency is:

A) -90°
B) 0°
C) 60.254°
D) -45°

Question 13

The filter in Figure 18-1 has a Roll-off of:

A) -40 dB per decade
B) -3 dB per decade
C) -20 dB per decade
D) -6 dB per decade

Question 14

The effectiveness of a filter in rejecting signals beyond cutoff frequency is a function of the filter roll-off rating.

Question 15

What is the output voltage, in Figure 18-1 at a frequency of 10 kHz?

A) 4.23 V
B) 5 V
C) 4.77 V
D) 1.50 V

Question 16

Figure 18-1
Given a frequency of 440 Hz, one Decade higher would be a frequency of:

A) 4 kHz
B) 220 Hz
C) 880 Hz
D) 4,400 Hz

Question 17

Figure 18-1
Figure 18-2
Which of the two response curves in Figure 18-2 A or B) represents the response of the circuit in Figure 18-1?

A) Curve A
B) Curve B

Question 18

Figure 18-3
The capacitive reactance in Figure 18-3 is equal to the resistance at the critical frequency.

Question 19

Figure 18-3
The circuit in Figure 18-3 is:

A) a high-pass filter
B) a band-stop filter
C) a low-pass filter
D) a band-pass filter

Question 20

Figure 18-3
The circuit in Figure 18-3 has a critical frequency of:

A) 318.3 kHz
B) 13.18 kHz
C) 5.0 kHz
D) 50.0 kHz

Question 21

The output voltage, in Figure 18-3 is how many dB down from the input voltage, at the critical frequency?

A) -20 dB
B) -0.707 dB
C) 0 dB
D) -3 dB

Question 22

The is defined as the difference between the high and low cut-off frequencies.

A) Q frequency range
B) bandwidth
C) roll-off
D) filter width

Question 23

Figure 18-5
The filter in Figure 18-5 has a Roll-off of:

A) -40 dB per decade
B) -3 dB per decade
C) -6 dB per decade
D) -20 dB per decade

Question 24

Which of the following equations is correct for calculating the critical or cut-off frequency for the circuit in Figure 18-5?

A) Fc = 1/2n LR)
B) Fc = 1/[2n L/R)]
C) Fc = 1/[2n LR)]
D) Fc = 2nL/R)

Question 25

Figure 18-9
Identify the filter circuit in Figure 18-9 above.

A) High Pass
B) Band Pass
C) Band Stop
D) Low Pass

Question 26

The output voltage of the circuit in Figure 18-5, at the cut-off critical) frequency is:

A) 7.07 V
B) 0.707 V
C) 4.9 V
D) 1.59 V

Question 27

The term "attenuation" refers to a:

A) phase shift
B) loss or reduction of signal strength
C) signal gain
D) unity gain

Question 28

Figure 18-6
Identify the filter circuit in Figure 18-6 above.

A) Band Stop
B) Low Pass
C) Band Pass
D) High Pass

Question 29

In a low-pass RC filter, having a cutoff frequency of 2 kHz, C = 80nF. Determine R.

A) 98.0 Ω
B) 44.7 Ω
C) 995 Ω
D) 22.7 Ω

Question 30

Identify the filter circuit in Figure 18-10 above.

A) Low Pass
B) High Pass
C) Band Stop
D) Band Pass

Question 31

Decibels are used to provide a _ between voltage levels.

A) comparison
B) common level
C) value
D) reference

Question 32

Figure 18-7
Identify the filter circuit in Figure 18-7 above.

A) Band Stop
B) Low Pass
C) High Pass
D) Band Pass

Question 33

A high-pass RC filter can be changed to a low-pass RC filter by _ .

A) adding another capacitor
B) reversing the position of the resistor and capacitor
C) adding another resistor
D) adding both another resistor and capacitor

Question 34

Figure 18-3
Figure 18-4
The frequency at which the output voltage of a filter is 70.7% of the input voltage is called the:

A) half-power point
B) critical frequency
C) break frequency
D) all of the above

Question 35

The critical frequency of the circuit in Figure 18-5 is:

A) 1.59 kHz
B) 135 Hz
C) 159 Hz
D) 60 Hz

Question 36

Figure 18-3
Figure 18-4
Which of the two response curves in Figure 18-4 A or B) represents the response of the circuit in Figure 18-3?

A) Curve A
B) Curve B

Question 37

Figure 18-5
The circuit in Figure 18-5 is:

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

Question 38

What is the output voltage, in Figure 18-3 at a frequency of 20 kHz?

A) 5 V
B) 1.21 V
C) 0.5 V
D) 4.77 V

Question 39

Figure 18-8
Identify the filter circuit in Figure 18-8 above.

A) Low Pass
B) Band Pass
C) High Pass
D) Band Stop

Question 40

The bandwidth of a resonant circuit is determined by two points on the curve known as .

A) the half power points
B) fcutoff
C) Q Point
D) both A and B

Question 41

A low-pass filter and a high-pass filter in parallel with each other, would form a _ filter.

A) band-stop
B) band-pass
C) all-pass
D) both A and B
E) none of the above