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WorksheetsModule 26201-20 Study Guide
Total questions: 33
Worksheet time: 17mins
What is the hertz rating of an AC circuit if the frequency is 20 cycles per 1/2 second?
40Hz
20Hz
10Hz
50Hz
Given: A circuit has an rms voltage of 120VAC. What is the peak-to-peak voltage?
340V
120V
170V
240V
A circuit has a peak voltage of 275V. What is the average voltage value?
175V
110V
200V
250V
Each of three equal capacitors in series has _____
one-third the applied voltage
the full applied voltage
half the applied voltage
twice the applied voltage
The formula for inductive reactance is _____
XL = 2πfL
XL = 1/2πfC
XL = R × I
XL = V/I
Given: An AC circuit containing resistance only. What is the current flow if the resistance is 15 ohms and the voltage is 150V?
10A
5A
15A
1A
The current in an inductive circuit _____ the voltage.
lags the voltage
leads the voltage
is equal to the voltage
is independent of the voltage
Unless otherwise noted, the calculations in AC circuits use _____
rms values
peak values
average values
instantaneous values
When frequency decreases, capacitive reactance _____?
increases
decreases
remains the same
becomes zero
Which of the following is true of the current in a capacitive circuit?
It leads the voltage
It lags the voltage
In sine wave terminology, the average value is _____
0.637 × peak value
0.707 × peak value
1.000 × peak value
0.500 × peak value
In AC circuits containing only resistance, _____
all DC rules and laws apply, including Ohm's law
the current leads the voltage by 90 degrees
the voltage leads the current by 90 degrees
power is not consumed
If the area of the plates of a capacitor is increased, the amount of capacitance _____?
increases
decreases
remains the same
becomes zero
The self-induced voltage across an inductance is equal to the change in _____ current with respect to time.
current
voltage
resistance
power
Given: A 30-microfarad capacitor in parallel with a 15-microfarad capacitor. The total capacitance is _____
45
15
30
60
Which of the following opposes any change in circuit current?
Capacitance
Inductance
"ELI the ICE Man" is used to remember _____
phase relationships that exist between voltage and current in an inductive circuit
the color code for resistors
the formula for calculating electrical power
the order of planets in the solar system
According to the power triangle, the apparent power is _____
VA (volt-amperes)
W (watts)
VAR (volt-ampere reactive)
kWh (kilowatt-hour)
Which of the following uses electromagnetic induction to transfer electrical energy from one circuit to another?
Transformer
Resistor
Capacitor
Diode
Given: A transformer has 200 turns in the primary, 100 turns in the secondary, and 150VAC applied to the primary. What is the voltage across the secondary?
75VAC
100VAC
50VAC
300VAC
Transformers in which the primary and secondary voltages are 180 out of phase are known as _____
unlike-wound transformers
auto transformers
step-up transformers
like-wound transformers
Maximum voltage is generated by rotating wire when the conductor is moving _____ .
across the field at 90°
parallel to the field
at 45° to the field
along the axis of rotation
If the time for one cycle is 0.1 second, the frequency is _____
10 Hz
0.1 Hz
100 Hz
1 Hz
If the phase angles of two sine waves are both 0 degrees then the waves _____
are in phase
are out of phase
have different frequencies
have opposite amplitudes
Calculate the true power in a 2A series RL circuit with a 100Ω resistor
400W
200W
100W
800W
Inductive reactance increases as the _____
frequency increases
frequency decreases
resistance increases
capacitance increases
The power factor can be defined as the ratio of true power to _____
apparent power
reactive power
resistive power
instantaneous power
For a given frequency, the capacitive reactance decreases with _____.
increasing capacitance
decreasing capacitance
increasing resistance
decreasing frequency
In a circuit that has both capacitance and resistance, the current will lead the voltage _____
by some angle between 0° and 90°
by exactly 90°
by exactly 0°
by more than 90°
If the vector diagram of two AC waveforms is a right angle, then the waves _____
are 90° out of phase
are in phase
are 180° out of phase
have the same frequency
In an inductive AC circuit, when the applied voltage is at its maximum negative value, the current is _____
zero
at its maximum positive value
at its maximum negative value
at its average value
The product of the source voltage and the total current is _____
apparent power
reactive power
resistive power
instantaneous power
In a parallel LC circuit, the voltage across the branches is _____
the same as the applied voltage
zero
double the applied voltage
half the applied voltage
