Delmar section 8
An RLC series circuit is powered by a 120-V, 60-Hz supply. It contains an inductor that has an inductive reactance of 50 Ω and a wire resistance of 10 Ω. What is the inductance of the inductor?
0.133 H
An RLC series circuit has a 60-Hz, 120V applied voltage. R = 50 Ω, XL = 137 Ω, and XC = 160 Ω. What is the inductance in the circuit?
0.363 H
An RLC parallel circuit has an applied voltage of 240 volts. R = 60 Ω, XL = 100 Ω, and XC = 32 Ω. What is the resistive current?
4A
An RLC parallel circuit has an applied voltage of 240 volts. R = 48 Ω, XL = 100 Ω, and XC = 36 Ω. What is the total current?
6.57 A
An RLC series circuit has R = 56 Ω, XL = 64 Ω, and XC = 37 Ω. What is the value of Z?
62.17 Ω
A parallel tank circuit operating at its resonant frequency has an impedance of 10,000 Ω. At the points on either side of the resonant frequency that define the bandwidth, the impedance is approximately _____.
7,070 Ω
An RLC parallel circuit has an applied voltage of 240 V. R = 60 Ω, XL = 80 Ω, and XC = 40 Ω. What is the apparent power?
1200 VA
An RLC series circuit has an applied voltage of 240 volts. R = 48 Ω, XL = 100 Ω, XC = 36 Ω, and Z = 80 Ω. What is the reactive power of the capacitor?
324 VARs
An RLC parallel circuit has an applied voltage of 240 volts. R = 48 Ω, XL = 100 Ω, and XC = 36 Ω. What is the circuit impedance (Z)?
80 Ω
An RLC series circuit has an applied voltage of 240 volts. R = 48 Ω, XL = 100 Ω, XC = 36 Ω, and Z = 80 Ω. What is the reactive power of the inductor?
900 VARs
What type of circuit is depicted in this image?
RLC series
During the period of time that the circuit is not at resonance, what is limited by the combination of inductive reactance and capacitive reactance?
current flow
In an RLC series circuit, _____ is the same through all components and the _____ are out of phase.
current; voltages
Which of these formulas is used to calculate apparent power?
d
As current increases, a magnetic field _________ around the inductor, inducing a voltage into the coil.
expands
What does this diagram depict?
exponential curve
Because inductive and reactance and capacitive reactance are 180° out of phase with each other in an RLC series circuit, mathematical addition must be used to find their sum.
false
Current can rise instantly through an inductor.
false
Inductors cannot be used to reduce current spikes and surges.
false
The current flowing through a pure capacitive element will lag the voltage by 90 electrical degrees.
false
The current flowing through a pure inductive element leads the applied voltage by 90 electrical degrees.
false
When Ohm's law is applied to the RLC series circuit values, the voltage drops developed across the inductor or capacitor can be lower than the applied voltage.
false
What can be determined when the values of inductance and capacitance are known?
frequency of resonance
When calculating resonant frequency, what does the value L represent?
inductance
If an RLC parallel circuit contains more inductive VARs than capacitive VARs, the circuit has a _____ power factor.
lagging
If an RLC series circuit contains more inductive VARs than capacitive VARs, the circuit has a _____ power factor.
lagging
If the current leads the voltage in an RLC series circuit, the power factor is referred to as _____.
leading
If the voltage is behind the current in an RLC series circuit, the power factor is referred to as _____.
leading
In an RLC series circuit, the point at which XL and XC are equal is called _____.
resonance
Because inductive reactance and capacitive reactance are 180° degrees out of phase with each other, they __________ from each other in an AC circuit.
subtract
LC parallel circuits are often referred to as _______________ circuits.
tanks
When an AC circuit contains elements of resistance, inductance, and capacitance connected in parallel, what is the voltage dropped across each element?
the same
Capacitive reactance is measured in ohms.
true
Capacitors help reduce or eliminate voltage spikes and surges by the current- limiting effect of a capacitor being affected by the frequency.
true
Capacitors oppose a change of voltage.
true
In an RLC parallel circuit, the phase angle difference between the applied voltage and the total current is determined by the ratio of resistance, inductance, and capacitance connected in parallel.
true
In an RLC series circuit, as frequency increases, inductive reactance increases and capacitive reactance decreases.
true
One joule is the amount of energy expended in applying a force of one Newton through a distance of one meter.
true
Subtraction of the inductive reactance and capacitive reactance in an RLC series circuit, permits the impedance of the circuit to become less than either or both of the reactances.
true
The current flowing through a pure resistive element in an RLC parallel circuit will be in phase with the applied voltage.
true
The impedance of an RLC parallel circuit is the reciprocal of the sum of the reciprocals of the legs.
true
The impedance of the RLC series circuit is the sum of resistance, inductive reactance, and capacitive reactance.
true
Thermal fuses are sensitive to heat instead of current.
true
This image represents current flow through the inductor. Ir
true
When using vector addition for inductive reactance and capacitive reactance, the larger value is reduced by the amount of the smaller value.
true
When using vector addition for inductive reactance and capacitive reactance, the smaller value is eliminated.
true
When values of inductive reactance and capacitive reactance become equal, they are said to be resonant.
true
If the power factor is corrected exactly so that the circuit is purely resistive, the power factor has a value of _____.
unity
An RLC series circuit has an applied voltage of 240 volts. R = 48 Ω, XL = 100 Ω, XC = 36 Ω, and Z = 80 Ω. What is the voltage drop across the capacitor?
108V
An RLC series circuit has an applied voltage of 240 volts. R = 51 Ω, XL = 100 Ω, and XC = 32 Ω. The voltage drop across the inductor is 282 V. What is the voltage drop on the resistor?
143.82 V
What is the typical capacitance rating of a typical MOV?
1900 pf
An RLC series circuit has an applied voltage of 240 volts. R = 48 Ω, XL = 100 Ω, XC = 36 Ω, and Z = 80 Ω. What is the total current?
3A
An RLC series circuit is powered by a 120-V, 60-Hz supply. It contains a capacitor that has an XL of 50 Ω. What is the capacitance of the capacitor?
53.05 μF
An RLC series circuit has R = 42 Ω, XL = 80 Ω, and XC = 24 Ω. What is angle theta?
53.13°
An RLC series circuit has an applied voltage of 277 volts. The current through the resistor is 3.5 A. What is the apparent power of the circuit?
969.5 VA
Which of these formulas is used to calculate total circuit current?
A
Which of these formulas is used to calculate true power produced by the coil?
A
Which of these formulas would be used to determine resonant frequency?
A
Which of these formulas would be used to determine the resonant value of inductance?
B
Which of these formulas would be used to determine bandwidth?
D
If the voltage in an RLC series circuit is ahead of the current, the power factor is referred to as _____.
Lagging
If an RLC parallel circuit contains more capacitive VARs than inductive VARs, the circuit has a _____ power factor.
Leading
If an RLC series circuit contains more capacitive VARs than inductive VARs, then the circuit has a _____ power factor.
Leading
When power is applied to a capacitor, it begins to charge to the peak value of the ________.
applied voltage
Which of these formulas is used to calculate parallel resonance?
b
In a parallel LC circuit, the difference in frequencies above and below resonance at which impedance is 0.707 of the maximum is called the _____ of the circuit.
bandwidth
Which of these formulas is used to calculate inductive current?
c
What are typically used to help eliminate voltage spikes and surges?
capacitors
The amount of voltage induced in the coil is proportional to the rate of ____________.
change of current
