WorksheetsAC - IC2
Total questions: 46
Worksheet time: 23mins
Which of the following can vary with ac, but not with dc?
Power
Frequency
Voltage
Magnitude
The length of time between a point in one cycle and the same point in the next cycle of an ac wave is the:
Frequency
Period
Magnitude
Polarity
In a sinusoidal wave, the measure from the mean level to the peak negative point.
Peak value
Average value
Negative peak value
Effective value
Which of the following is not a general characteristic of an ac wave?
The wave shape is identical for each cycle
The polarity reverses periodically
The electrons always flow in the same direction
There is a definite frequency
A sine wave:
Always has the same general appearance
Has instantaneous rise and fall times
Is in the same phase as a cosine wave
Rises very fast, but decays slowly
The value of a sinusoidal voltage waveform at any given time.
Root mean square
Instantaneous
Effective
Average
A sine wave rises from 0 to 50V. What is the voltage level at 30 degrees?
16.667 V
25 V
4.1667 V
43.3 V
A signal has a frequency of 1770 Hz. The angular frequency is:
1770 radians per second
11,120 radians per second
282 radians per second
Impossible to determine from the data given
A voltage rating which will have the same heating effect to a resistor as with a dc voltage supply.
RMS
AC
Effective
All of these
In a 117-V utility circuit, the pk-pk voltage is:
82.7 V
165 V
234 V
331 V
A phase difference of 540 degrees would more often be spoken of as:
An offset of more than one cycle
Phase opposition
A cycle and a half
1.5 Hz
Which of the following is the peakiest?
square wave
triangular wave
sinusoidal wave
rectangular wave
Inductors in dc circuits behaves like ___
Short
Open
Reactive
Resistive
The total opposition to the flow of alternating current.
Resistance
Impedance
Admittance
Reactance
A coil has an inductance of 100 mH. What is the reactance at a frequency of 1000 Hz?
0.628 ohms
6.28 ohms
62.8 ohms
628 ohms
If a 30 ohm R and a 40 ohm XL are in series with 100V applied, find the impedance.
40 ohms
50 ohms
30 ohms
In a purely inductive load supplied with ac voltage, ___
The current leads the voltage by 90deg
The voltage leads the current by 90deg
There is only true power
The impedance is zero
If the current in an ac-circuit leads the voltage by 90deg, the circuit is
resistive
inductive
capacitive
purely inductive
If a 30 ohm R and a 40 ohm XL are in series with 100V applied, find the phase angle between the voltage and current.
V leads I by 53.1 deg
I lags I by 53.1 deg
I leads V by 36.9 deg
I lags V by 36.9 deg
A 60 ohms XL and a 40 ohms XC is in series. When supplied by a 120Vac, find the voltage across the capacitor.
48 V
120 V
240 V
360 V
What is the voltage across a capacitor with reactance of 100 ohms in series of a 100 ohms resistance if supplied with 100 Vac?
50 V
100 V
70.7 V
63.7 V
The reciprocal of susceptance.
Resistance
Admittance
Impedance
Reactance
Susceptance and conductance add to form:
Impedance
Inductance
Reactance
Admittance
The admittance of a parallel RLC circuit is found to be the _____ sum of conductance and susceptances.
algebraic
vector
arithmetic
phasor
The reciprocal of electrical impedance.
Susceptance
Reluctance
Admittance
Conductance
Find the total reactance of a circuit with 100mH inductor connected in parallel to a 1uF capacitor, if f=100Hz.
0.0165 ohms
65.4 ohms
60.44 ohms
1654.38 ohms
A parallel RL circuit with R = 60Ω, and XL = 40Ω has a total impedance of
24.3 Ω
33.3 Ω
28.3 Ω
38.3 Ω
The circuit admittance is Y = 0.3 - j0.8, the circuit is
resistive
capacitive
inductive
reactive
Suppose a resistor of 51.0 Ω, an inductor of 22.0 μH, and a capacitor of 150 pF are in parallel. The frequency is 1.00 MHz. What is the complex impedance?
51.0 - j14.9
51.0 + j14.9
46.2 - j14.9
46.2 + j14.9
Suppose a parallel circuit has 10 Ω of resistance and 15 Ω of reactance. An ac rms voltage of 20 V is applied across it. What is the total current?
2.00 A
2.40 A
1.33 A
0.8 A
The vector sum of the true and reactive powers.
Apparent power
Total power
Phasor
Vector
An impedance of 20 + j75 is supplied with 100Vac. Find the reactive rms power.
124.48 VAR
33.2 VAR
128.83 VAR
128.83 VAR
A circuit draws 1kA at a voltage of 20kV. If the power factor of the circuit is 0.8, what is the reactive power?
12 MVAR
16 MVA
12 MVA
16 MVAR
The cosine of a lead or a lag in the circuit.
Power factor
Reactive factor
Phase angle
Phase shift
The ratio of the resistance to the impedance in an AC circuit.
Power factor
Reactive factor
Phase angle
Phase shift
Which of the following is the unit of power factor?
Unitless
Watts per Volt-Ampere
Ohm per Ohm
All of these
The ratio of the reactive power and the apparent power in a circuit.
Power factor
Reactive factor
Apparent factor
All of the above
Find the power factor in a circuit having total impedance of 20+j75, if supplied with 100Vac.
0.26
0.97
75.07
0.76
What is the power factor (pf) of a series RL circuit having R=60 Ω and XL=20 Ω?
0.93
0.63
0.95
0.71
The condition in which the inductive and capacitive reactances cancels out, making the impedance purely resistive.
Power factor correction
Fine Tuning
Resonance
Reactive factor cancellation
Which of the following is true about series resonance?
Maximum impedance
Current is minimum and out of phase with the supply voltage
Voltage is maximum at L or C alone
Voltage at R is maximum
In series resonance, at a frequency less than the resonant frequency, the circuit impedance becomes _____
Capacitive
Inductive
Purely resistive
Maximum
The higher the value of the Q the _____
More selective the circuit
Less selective the circuit
More sensitive the circuit
Less sensitive the circuit
What is the resonant frequency of a circuit when L of 25 microhenry and C of 10 picofarad are in parallel?
63.7 MHz
10.1 MHz
63.7 kHz
10.1 kHz
A series circuit at resonance would mean, the circuit is
resistive
capacitive
inductive
reactive
Characteristic of the current in a series R-L-C circuit at resonance.
It is dc
It is zero
It is a minimum
It is at maximum
