Deck 9: Capacitors

Question 1

What is the capacitance of a capacitor that drops 50V and stores 0.500 of charge?

A) 0.1
B) 0.001
C) 0.01
D) 1

Answer 1

0.01

Question 2

If a 0.022 $\mu \mathrm { F }$ , 0.022 $\mu \mathrm { F }$ and 0.05 $\mu \mathrm { F }$ capacitor are connected in series across a 25 V source, the voltage drop across the largest capacitor equals________

A) 10.2 V
B) 11.8 V
C) 17.5 V
D) 4.51 V

Answer 2

4.51 V

Question 3

Electrolytic capacitors are ideal for alternating current applications.

Answer 3

False

Question 4

A capacitorW ill fully charge in about five time constants.

Question 5

Efficient filtering is directly related to RC time constant.

Question 6

When two capacitors are connected in series across a dc source, the smallest capacitor drops the largest Voltage.

Question 7

The voltage rating of a capacitor indicates the voltage itW ill charge up to.

Question 8

Capacitance is the ability to store Voltage.

Question 9

Capacitance is a capacitor?s ability to store resistance.

Question 10

When two capacitors are connected in parallel across a dc source, the smaller capacitor drops the larger Voltage.

Question 11

To find the total capacitance of two capacitors in parallel, you must combine them using a similar procedure as resistors in parallel.

Question 12

How much charge is stored in a 0.022 capacitor that drops 22 V?

A) 4.84
B) 0.484 11ec8331_2bc9_6de3_8198_1b1aab5e15e3_TB34225555_11
C) 48.4 11ec8331_2bc9_6de3_8198_1b1aab5e15e3_TB34225555_11
D) 0.0484 11ec8331_2bc9_6de3_8198_1b1aab5e15e3_TB34225555_11

Question 13

What is one time constant of a 4.7 capacitor in series with a 22 resistor?

A) 1.03 ms
B) 103 ms
C) 0.103 ms
D) 10.3 ms

Question 14

Leakage through a capacitor is undesirable.

Question 15

If the distance between the plates of a capacitor increases, the capacitance decreases.

Question 16

If a 0.05 $\mu \mathrm { F }$ and 0.1 $\mu \mathrm { F }$ capacitor are connected in parallel across a 20 V source, the total capacitance equals______ and each capacitor drops________

A) 0.10 $\mu \mathrm { F }$ , 20 V
B) 0.05 $\mu \mathrm { F }$ , 15 V
C) 0.15 $\mu F$ , 10 V
D) 0.15 $\mu \mathrm { F }$ , 20 V

Question 17

A capacitor blocks dc and passes ac.

Question 18

If the plate area of a capacitor decreases, the capacitance decreases.

Question 19

A capacitor can fully charge in one time constant.

Question 20

If the dc Working voltage of a capacitor is 100 V, the dielectric must With stand ________.

A)85V
B)75V
C)100V
D)220V

Question 21

At what frequency is a 2000 capacitor operating if its reactance is 745 ?

A) 107 kHz
B) 1.01 kHz
C) 10.1 kHz
D) 1010 Hz

Question 22

How long will it take a 0.047 capacitor to fully charge through a 100 resistor?

A) 235 ms
B) 2.35 s
C) 0.235 ms
D) 23.5 ms

Question 23

If an uncharged capacitor, a resistor, a switch and a 12 V battery are connected in series,What is the voltage across the capacitor at the instant the switch is closed?

A)24V
B)0V
C)6V
D)12V

Question 24

If a 1 $\mu \mathrm { F }$ , 2.2 $\mu F$ and 0.05 $\mu \mathrm { F }$ capacitor are connected in series, $\mathrm { C } _ { \mathrm { T } }$ is less than________

A) 0.001 $\mu \mathrm { F }$
B) 0.05 $\mu \mathrm { F }$
C) 2.2 $\mu \mathrm { F }$
D) 1 $\mu \mathrm { F }$

Question 25

What is the minimum dc working voltage rating for a capacitor that must drop 120 V_RMS ?

A) 84.8 V
B) 120 V
C) 170 V
D) 339 V

Question 26

A capacitor that transfers an ac signal from one stage to another is called a ________ capacitor.

A)filter
B)coupling
C)transfer
D)bypass

Question 27

If a 4.7 capacitor and a 10 resistor are connected in series across 25 , approximately how much voltage will the resistor drop after charging for just one time constant?

A) 23.8 V
B) 21.6 V
C) 15.8 V
D) 9.20 V

Question 28

What is the capacitance that stores 1.175 $\mu \mathrm { C }$ of charge and drops 25 V?

A) 0.47 $\mu F$
B) 0.047 $\mu \mathrm { F }$
C) 4.7 $\mu \mathrm { F }$
D) 47 $\mu \mathrm { F }$

Question 29

If a 22 $\mu F$ capacitor is connected to a 15 V 400 Hz source, its current equals______

A) 55 mA
B) 829 mA
C) 18.1 mA
D) 1.81 A

Question 30

How long will it take a 1 capacitor to completely discharge through a 47 resistor?

A) 235 s
B) 47 ms
C) 47 s
D) 235 ms

Question 31

If an uncharged capacitor, a resistor, a switch and a 12 V battery are connected in series,W hat is the voltage across the capacitor after it is fully charged?

A)12V
B)-6V
C)6V
D)24V

Question 32

If four 0.022 $\mu \mathrm { F }$ capacitors are connected in parallel, $\mathrm { C_T }$ equals_______

A) 0.022 $\mu \mathrm { F }$
B) 0.049 $\mu \mathrm { F }$
C) 0.088 $\mu \mathrm { F }$
D) 0.044 $\mu \mathrm { F }$

Question 33

If a 0.1 capacitor and a 2.2 resistor are connected in series across 30 , how much voltage will the capacitor drop after charging for just one time constant?

A) 25.9 V
B) 19.0 V
C) 29.4 V
D) 28.5 V

Question 34

How long will it take to completely charge a 0.047 capacitor through a 1 resistor?

A) 0.029 s
B) 0.047 s
C) 0.235 s
D) 0.47 s

Question 35

If a 0.1 $\mu F$ , 0.1 $\mu \mathrm { F }$ and 0.05 $\mu \mathrm { F }$ capacitor are connected in series across a 75 V source, the voltage drop across the smallest capacitor equals_____

A) 50 V
B) 100 V
C) 37.5 V
D) 18.8 V

Question 36

If an uncharged capacitor, a resistor, a switch and a 12 V battery are connected in series, at approximatelyW hat timeW ill the capacitor reach full charge?

A)12 × R × C
B)R × C
C)5 × R × C
D)The time cannot be predicted.

Question 37

If the frequency applied to a capacitor increases, the capacitive reactance ________.

A)decreases
B)remains the same
C)varies up and down
D)increases

Question 38

If a 1 capacitor and a 10 resistor are connected in series across 20 , , approximately how much voltage will the capacitor drop after charging for just one time constant?

A) 12.6 V
B) 11.0 V
C) 12.1 V
D) 17 V

Question 39

How much charge is stored in a 0.47 capacitor that drops 18 V?

A) 84.6
B) 8.46
C) 846
D) 0.846

Question 40

If a 4.7 $\mu \mathrm { F }$ capacitor operates at 10 kHz, $X _ { C }$ equals____

A) 3.39 $\Omega$
B) 339
C) 294
D) infinite $\Omega$

Question 41

A common use for electrolytic capacitors found in power supplies is ________.

A)decoupling
B)filtering
C)passing AC
D)blocking DC

Question 42

What is one time constant of a 47 capacitor in series with a 120 resistor?

A) 5.64 s
B) 0.564 ms
C) 54.6 s
D) 564 ms

Question 43

If a 0.047 $\mu F$ , 0.047 $\mu \mathrm { F }$ and 0.47 $\mu \mathrm { F }$ capacitor are connected in series across a 25 V source, the total capacitance equals ____________and each 0.047 $\mu F$ capacitor drops___

A) 0.564 $\mu F$ ,1.2V
B) 0.022 $\mu \mathrm { F }$ ,25 V
C) 0.022 $\mu F$ ,11.9 V
D) 0.564 $\mu F$ ,11.9 V

Question 44

At what frequency is a 0.001 $\mu \mathrm { F }$ capacitor operating if its reactance is 45 $\mathrm { k } \Omega$ ?

A) 3.54 MHz
B) 3.54 kHz
C) 354 kHz
D) 35.4 kHz

Question 45

If a 22 $\mu \mathrm { F }$ and $\mu F$ capacitor are connected in parallel across a 15 V source, the total capacitance equals _________and the 22 $\mu \mathrm { F }$ capacitor drops______

A) 18 $\mu \mathrm { F }$ , 5.2 V
B) 122 $\mu \mathrm { F }$ ,15 V
C) 1220 $\mu F$ , 30 V
D) 18 $\mu \mathrm { F }$ ,15V

Question 46

The time constant for a capacitor for each time period is:

A)63% of the increase in value.
B)a constant factor.
C)37% of the decrease in value.
D)all of these.

Question 47

How long will it take for a 22 capacitor to completely charge through a 47 resistor?

A) 5.17 s
B) 8.272 s
C) 1.034 s
D) 2.068 s

Question 48

Electrolytic capacitors differ from many other capacitors in construction in that they are:

A)polarized.
B)larger.
C)smaller.
D)sensitized.

Question 49

If a 0.047 $\mu \mathrm { F }$ capacitor operates at 220 kHz , $X _ { C }$ equals______

A) 154 $\Omega$
B) 15.4 $\mathrm { k } \Omega$
C) 1.54 $k \Omega$
D) 15.4 $\Omega$

Question 50

When connecting a large electrolytic capacitor to a circuit With a 100 VDC source, place the negative end of the capacitor ________.

A)towards the negative side of the source
B)towards the positive side of the source
C)in either position; the polarity is not important

Question 51

In a capacitive AC circuit, the phase relationship between the voltage and the current is such that the:

A)current is 180 degrees out of phase with Voltage.
B)current is leading the Voltage.
C)voltage is leading the current.
D)voltage is 360 degrees out of phase with current.

Question 52

When capacitors are connected in series, their total capacitance act like:

A)resistance connected in series-parallel.
B)resistance connected in parallel.
C)resistance connected in series.
D)all of these.

Question 53

Reactive power (Pr)in a capacitor is defined as the rate atW hich a capacitor stores or returns energy and is measured in:

A)watts reactive.
B)volt-ampere reactive.
C)current per time constant.
D)volts per time constant.

Question 54

$$\text { Figure } 9 < 1$$

-What is C_T in Figure 9-1?

A) 70.1 $\text { uF }$
B) 25.2 $\mu \mathrm { F }$
C) 8.78 $\mu \mathrm { F }$
D) 82 $\mu \mathrm { F }$

Question 55

When capacitors are connected in parallel, their total capacitance act like:

A)resistance connected in parallel.
B)resistance connected in series-parallel.
C)resistance connected in series.
D)all of these.

Question 56

How long will it take for a 22 $\mu \mathrm { F }$ capacitor to completely discharge through a 4.7 $\mathrm { k } \Omega$ resistor?

A) 0.103 s
B) 0.827 s
C) 0.517 s
D) 0.207 s

Question 57

Electrolytic capacitors must be connected into a circuit such that:

A)reversal of polarity does not happen.
B)positive lead to positiveVoltage; negative lead to negative Voltage.
C)voltage rating marked is not exceeded.
D)all of these.

Question 58

If a 47 $\mu \vec { F }$ capacitor is connected to a 20V, 400Hz source, the current is__________

A) 0.851 A
B) 2.36 A
C) 8.51 A
D) 425 A

Question 59

How much voltage is dropped across a 150 capacitor after 3.33 seconds if it is charged by a 50 V source through a 22 resistor?

A) 49 V
B) 31.8 V
C) 43.3 V
D) 47.5 V

Question 60

The time constant of a capacitor is:

A)the time required to charge to 63% or discharge to 37%.
B)directly proportional to the resistance in the circuit.
C)directly proportional to the capacitance in the circuit.
D)all of these.

Question 61

A commonplace use for capacitors in electronics is to:

A)block ACVoltages.
B)pass DCVoltages only.
C)pass both AC and DCVoltages.
D)block DCVoltages.

Question 62

A 65 Vrms signal is applied to a 10 F capacitor.What is the total peak current?

A)6.5 kA
B)6.5 A
C)153 mA
D)not enough information

Question 63

The removal of high frequency transient voltages With a capacitor is called:

A)ac blocking.
B)decoupling.
C)coupling.
D)bypassing.

Question 64

What is the small amount of power lost in a capacitive circuit due to the internal resistance of the capacitors?

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

Question 65

A test instrument designed to be used for the testing of capacitors is the ________.

A)oscilloscope
B)LCR Meter
C)digital multimeter
D)analog multimeter

Question 66

With three capacitors in series, the current lags the voltage by:

A)30 degrees.
B)90 degrees.
C)45 degrees.
D)none of the above.