Deck 12: Capacitors

Question 1

Figure 12-1
The charge voltage across each capacitor in Figure 12-1 is inversely proportional to the size of the capacitor in microfarads.

Answer 1

True

Question 2

Figure 12-1
A capacitor stores voltage in its electromagnetic field.

Answer 2

False

Question 3

Increasing the distance between the plates of a capacitor increases the capacitance.

Answer 3

False

Question 4

A material with a high dielectric constant increases the capacitance.

Question 5

Figure 12-1
The material used in between the plates of a capacitor is called the dielectric.

Question 6

Figure 12-1
Which of the following capacitors is polarized and will be destroyed if connected in reverse polarity?

A) ceramic
B) paper
C) electrolytic
D) mylar

Question 7

Figure 12-1
All dielectrics are made from conducting material.

Question 8

Figure 12-1
Which capacitor in Figure 12-1 is charged to the highest voltage?

A) C1
B) C2
C) C3

Question 9

Figure 12-1
The largest capacitor in Figure 12-1 has the highest charge voltage.

Question 10

Current lags the voltage by 90 degrees in a capacitor.

Question 11

Five time constants are required to fully charge or discharge a capacitor.

Question 12

Figure 12-1
Determine the capacitance when Q = 75 µC and V = 20 V.

A) 3.75 µF
B) 9.8 µF
C) 0.27 µF
D) 150 µF

Question 13

Energy is stored in a capacitor in a magnetic field, concentrated in the dielectric.

Question 14

Increasing the plate area of a capacitor increases the capacitance.

Question 15

Figure 12-1
A charged capacitor could be considered a voltage source.

Question 16

Figure 12-1
A discharged capacitor has a positive charge on its plates.

Question 17

Capacitance is the measure of a capacitor's ability to store an electrical charge.

Question 18

Figure 12-1
The current through a capacitor is always maximum at the start of the first time constant.

Question 19

The capacitive reactance of a capacitor is inversely proportional to the frequency, and directly proportional to the capacitance.

Question 20

Exceeding the dielectric strength of a capacitor means you have applied too high a voltage, and probably destroyed the capacitor.

Question 21

Figure 12-4
The charge of a capacitor is:

A) on the bottom plate only
B) on the top plate only.
C) on both plates
D) in the dielectric.

Question 22

If the distance between the plates of a capacitor is increased, the capacitance _ .

A) remains the same
B) increases
C) decreases
D) can't tell with information given

Question 23

Figure 12-1
The three capacitors in series in Figure 12-1 have an equivalent value:

A) less than the value of the smallest capacitor
B) equal to the product of the three values
C) equal to the sum of the three values

Question 24

Figure 12-1
The main disadvantage of an electrolytic capacitor is:

A) low voltage values
B) low leakage current
C) high leakage current
D) low capacitance values

Question 25

Three 2 µF capacitors are connected in parallel. What is the total capacitance?

A) 6.0 µF
B) 2.0 µF
C) 66.0 µF
D) 0.66 µF

Question 26

If the capacitor in Figure 12-3 is 0.1 µF and it is replaced by a 0.47 µF capacitor, which value capacitor will have the higher reactance?

A) the 0.1 µF capacitor
B) the 0.47 µF capacitor

Question 27

Figure 12-1
Calculate the equivalent capacitance of the three series capacitors in Figure 12-1.

A) 0.8 µF
B) 0.060 µF
C) 0.01 µF
D) 0.58 µF

Question 28

Figure 12-2
Assuming the capacitors in Figure 12-2 are non-polarized electrolytic capacitors, what is the maximum AC rms voltage that can safely be applied to the circuit?

A) 100 V
B) 49.5 V
C) 24 V
D) 35 V

Question 29

Figure 12-1
A capacitor rated at 10,000 µF would typically have what kind of dielectric?

A) aluminum oxide
B) ceramic
C) tantalum oxide
D) Both A and B are correct

Question 30

Figure 12-1
A capacitor has a capacitance of 0.1 µF with air as the dielectric. If the dielectric material is changed from air to a ceramic material with a dielectric constant of 600, what is the new capacitance? Note: Neither air nor Ceramic capacitors this large are available.)

A) 6.28 µF
B) 600 µF
C) 60 µF
D) 0.006 µF

Question 31

Figure 12-4
Given the circuit in Figure 12-4, what is the approximate voltage across the capacitor at the end of 1 second after the 10V source is connected?

A) 10 V
B) 6.3 V
C) 63 V
D) 0.707 V

Question 32

A capacitor has a plate area of 0.01 square meters. A second capacitor has a plate area of 0.02 square meters. If the first capacitor is 0.1 µF, what is the value of the second capacitor if all other physical characteristics are identical?

A) 0.2 µF
B) 0.05 µF
C) 0.1 µF
D) 0.4 µF

Question 33

A capacitor produces a capacitive reactance of 18.086 kΩ with an applied voltage having a frequency of 400 Hz. What is the capacitor value?

A) 22 µF
B) 0.22 µF
C) 0.47 µF
D) 0.022 µF

Question 34

A discharged capacitor has charges on its plates.

A) unequal
B) no
C) negative
D) equal

Question 35

Figure 12-2
What is the maximum DC voltage that can safely be applied to the circuit in Figure 12-2?

A) 100 V
B) 185 V
C) 50 V
D) 35 V

Question 36

If the capacitor in Figure 12-3 is 0.1 µF and it is replaced by a 0.47 µF capacitor, which value capacitor will cause the higher circuit current?

A) the 0.1 µF capacitor
B) the 0.47 µF capacitor

Question 37

What would we call a 0.000000000001 F capacitor?

A) 1 F
B) 1 pF
C) 0.001 F
D) 1 µF

Question 38

One time constant can be solved by:

A) subtracting capacitance from reactance
B) dividing capacitance by resistance
C) adding capacitance to resistance
D) multiplying capacitance by resistance

Question 39

Calculate the reactance of the capacitor if it has a value 1.0 µF and the frequency is 10 kHz.

A) 159.0 Ω
B) 198.75 Ω
C) 227.87 Ω
D) 15.9 Ω

Question 40

Figure 12-2
Calculate the equivalent value of the parallel capacitors in Figure 12-2.

A) 15510 µF
B) 227.24 µF
C) 90 µF
D) 4.7 µF

Question 41

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1.0 µF __________

Question 42

A capacitor with a 20 volt charge is being fully discharged. How many volts are across the capacitor after the third time constant?

A) 1 V
B) 12.64 V
C) 5 V
D) 19 V

Question 43

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.10 µF __________

Question 44

Why are capacitors used as coupling components in many ac circuits?

A) because the dielectric has a high dc resistance
B) because they pass ac and block dc
C) because they pass dc and block ac
D) both A and B

Question 45

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.47 µF __________

Question 46

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.001 µF __________

Question 47

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 4000 µF __________

Question 48

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 100 µF __________

Question 49

If an open capacitor is checked with an analog ohmmeter, the meter should show:

A) infinity
B) zero
C) movement from zero to infinity
D) movement from infinity to zero

Question 50

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1.0 µF __________

Question 51

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.01 µF __________

Question 52

If three capacitors with values of 33 µF, 40 µF and 88 µF were connected in parallel, what is the total capacitance?

A) 53.7 µF
B) 15 µF
C) 102.1 µF
D) 161 µF

Question 53

Using the formula for capacitive reactance, as frequency decreases:

A) capacitive reactance decreases
B) capacitive reactance changes by 90 degrees
C) capacitive reactance remains the same
D) capacitive reactance increases

Question 54

If the applied frequency is 1 kHz and the capacitance is 10 µF, calculate the capacitive reactance XC.

A) 0.063 Ω
B) 15.9 kΩ
C) 15.9 MΩ
D) 15.9 Ω

Question 55

Phase relationship of voltage and current in a reactive circuit is:

A) an in-phase relationship
B) dependent upon circuit current
C) an out-of-phase relationship
D) dependant upon the magnitude of the applied voltage

Question 56

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1000 µF __________

Question 57

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 100 µF __________

Question 58

Power that is stored from the source and then returned to the source is called:

A) reactive power
B) instantaneous power
C) apparent power
D) true power

Question 59

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 10 µF __________

Question 60

How long does it take to fully charge a 5 µF capacitor in series with a 5 MΩ resistor?

A) 25 seconds
B) 125 milliseconds
C) 125 seconds
D) 125 microseconds

Question 61

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.002 µF __________

Question 62

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.01 µF __________

Question 63

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1.0 µF __________

Question 64

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1000 pF __________

Question 65

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1000 µF __________

Question 66

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.0001 µF __________

Question 67

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.001 µF __________

Question 68

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 100 pF __________

Question 69

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.022 µF __________

Question 70

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1000 pF __________

Question 71

An amplifier with a switched-capacitor circuit has an input resistor value of 20K ohms. If you want the switched-capacitor to emulate a 10K ohm resistor, at what frequency must the switch be operated? The value of the capacitor is 1000pF.

A) 20KHz
B) 100KHz
C) 50KHz
D) 25KHz

Question 72

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.01 µF __________

Question 73

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.01 µF __________

Question 74

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 10 pF __________

Question 75

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1.0 µF __________

Question 76

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 10.0 µF __________

Question 77

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 1.0 µF __________

Question 78

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 100 µF __________

Question 79

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 0.022 µF __________

Question 80

Write the word or phrase that best completes each statement or answers the question.
Complete the following tables: Frequency = 60 Hz
Capacitance Reactance 100 pF __________