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WorksheetsELECS 9
Total questions: 50
Worksheet time: 8mins
In a 20 Vac series RC circuit, if 20 V is measured across the resistor and 40 V is measured across the capacitor, the applied voltage is:
45 V
50 V
55 V
60 V
Select the equation below that represents the relationship between charge, capacitance, and voltage for a capacitor.
Q = CV
C = QV
V = IR
When is a capacitor fully charged?
when the voltage across its plates is 1/2 of the voltage from ground to one of its plates
when the current through the capacitor is the same as when the capacitor is discharged
when the voltage across the plates is 0.707 of the input voltage
when the current through the capacitor is directly proportional to the area of the plates
What is the reactive power in the given circuit?
0 VAR
691 μ VAR
44.23 mVAR
1.45 kVAR
What is the angle theta value for a
5.6 μ F capacitor and a 50-ohm resistor in series with a 1.1 kHz, 5 Vac source?
27.3 degrees
62.7 degrees
–27.3 degrees
–62.7 degrees
When a 4.7 F capacitor is connected to a 1 kHz source, what is its capacitive reactance?
4.7 ohms
29.5 ohms
34 ohms
213 ohms
What is the total capacitance?
1 F
12 F
0.615 F
8 F
What is this circuit?
bandpass filter
high-pass filter
low-pass filter
differentiator
After which time constant can a capacitor be considered to be fully charged?
first
third
fifth
seventh
You could increase the time constant of an RC circuit by
adding a resistor in parallel with the circuit resistance
adding a capacitor in parallel with the circuit capacitance
increasing the amplitude of the input voltage
exchanging the position of the resistor and capacitor in the circuit
A capacitor's rate of charge is considered:
magnetic
a current block
linear
exponential
A resistor and an output capacitor form a series circuit with a square wave applied. The circuit is:
an integrator
a differentiator
a multiplier
a divider
If an open capacitor is checked with an ohmmeter, the needle will:
stay on zero
stay on infinity
move from zero to infinity
move from infinity to zero
What is the circuit's total current?
4.57 mA
9.327 mA
11.570 mA
13.830 mA
As a capacitor is being charged, current flowing into the capacitor will:
increase
decrease
remain the same
cannot tell
What is the phase shift between the voltage across the resistor and the voltage from the source?
VR leads VS by 17°
VR leads VS by 73°
VR lags VS by 73°
VR lags VS by 17°
A capacitor stores energy within a dielectric between the conducting plates in the form of:
a magnetic field
positive voltage
negative voltage
an electric field
As a capacitor is being charged, the voltage across its terminals will:
increase
decrease
remain the same
oppose the source
With a 500 kHz signal source, what would be the value of a capacitor yielding a capacitive reactance of 1 kΩ ?
318 pF
2 nF
3.18 μ F
2 F
After a capacitor has charged for 1 tc, what percentage of current remains in the resistor?
63.2
36.8
13.5
5.0
If a current of 40 mA flows through a series circuit consisting of a 0.4 μ F capacitor and a resistor in series with a 4 kHz, 40 Vac source, what is the total circuit impedance?
10 Ω
100 Ω
1 k Ω
1 M Ω
What is the capacitance of the circuit shown in the given circuit?
0.066 μ F
0.9 μ F
65.97 pF
900 pF
In an ac circuit, an output capacitor and a resistor are connected in series with an ac signal. What filter action will be the result?
bandpass
low-pass
high-pass
band-stop
What is the total opposition to current in a series RC circuit called?
impedance
inductance
reactance
resistance
Which of the following statements is true?
The voltage to which a capacitor is charged can change instantaneously.
The current in a capacitive circuit takes time to change.
A fully charged capacitor appears as a short to dc current.
An uncharged capacitor appears as a short to an instantaneous change in current.
In a capacitive circuit, current flow is limited to
charging periods
discharging periods
neither charging periods nor discharging periods
both charging periods and discharging periods
What circuit has the following frequency response?
bandpass filter
high-pass filter
low-pass filter
integrator
A capacitor is constructed of two parallel:
conductors
semiconductors
inductors
dielectrics
Which of the following determines the capacitance of a capacitor?
Plate area, dielectric strength, and plate separation
Voltage rating, dielectric constant, and temperature coefficient
Temperature coefficient, plate area, and plate separation
Plate area, dielectric constant, and plate separation
Most older types of paper capacitors have been replaced by which type of construction?
electrolytic
plastic film
oxide casing
waxed paper
If C1, a 4.7 F capacitor, and C2, a 3.3 F capacitor are in series with 18 Vdc applied, what is the voltage across C1?
3.3 V
7.4 V
6.6 V
9.4 V
What is the impedance of a series RC circuit that consists of a 0.22 μ F capacitor and a 200-ohm resistor connected to a 3 kHz source?
214 ohms
313 ohms
414 ohms
880 ohms
What is the reactance value for a capacitor installed in a dc circuit?
zero
moderate
infinite
cannot tell
In a purely capacitive circuit,
current leads voltage by 90°
voltage leads current by 90°
current lags voltage by 90°
current and voltage have a phase relationship of 0°
How long would it take the capacitor in the given circuit to completely discharge if the switch was in position 2?
22 ms
69 ms
345 ms
420 ms
What is the capacitive reactance if I = 1 amp, V = 2 volts, C = 5 F, and frequency = 10 Hz?
0.2 Ω
0.5 Ω
0.02 Ω
0.003 Ω
What is wrong with a leaky capacitor?
It is open.
It is shorted.
The dielectric resistance has increased.
The dielectric resistance has decreased.
What is the value of a capacitor labeled 102?
10,000 pF
1000 pF
1000 μ F
10,000 μ F
If the dielectric constant of a capacitor is decreased, then its capacitance will:
increase
decrease
remain the same
be destroyed
What is the dielectric constant for ceramic?
between 6 and 8000
5.0
between 5 and 1000
3000
What is the voltage across a capacitor after being charged from a 100 V source for a period of one time constant?
37.8 V
38 V
63 V
101 V
What is the dc charging/discharging time constant for the circuit?
294 ps
13.5 ms
21.25 ms
2.16 Gs
Power stored from the source and then returned to the source is called:
apparent power
impedance power
reactive power
true power
Capacitor value markings are usually:
alphanumeric
color dabs
standard
white print
A source voltage across a capacitor will:
lead the current by 90 degrees
lead the current by 180 degrees
lag the current by 90 degrees
lag the current by 180 degrees
How long would it take the capacitor in the given circuit to completely charge if the switch was in position 1?
22 ms
69 ms
345 ms
440 ms
An 8 V power source is charging a capacitor. How many volts will be across the capacitor at the second time constant?
1 volt
3 volts
5 volts
7 volts
The material used between the plates of a capacitor is called its:
insulation material
dielectric material
separation material
plate-divider material
When a circuit consists of a capacitor and a resistor in series with a voltage source, and the voltage across the resistor is zero, then the capacitor is:
charging
discharging
fully charged
fully discharged
Which material has the highest dielectric strength?
Air
Paper
Mica
Oil
