AMS 116 Unit 3
Inductance is represented by the letter __________.
"L"
Select the degrees of AC generator armature rotation where zero induced current occurs.
0.0 degrees 180 degrees
Select the below AC sine wave frequency with the longest wavelength.
1.0 kHz
During one time constant (TC), a capacitor will charge _____ %. (enter only the numeric value rounded to 3-decimal places if necessary)
63.2
Theta will be an angle between 0.0 degrees and _____ degrees.
90
The letters "R" "L" and "C" in RLC circuit represent _________. (select all of the below that apply)
Capacitance Inductance Resistance
In which AC circuit would the voltage lag the current?
Capacitive
What opposes current in an RC circuit? (select all that apply)
Capacitive Reactance Resistance
Select all that is true about alternating current (AC) compared to direct current (DC).
Current flow periodically changes direction. Polarity does not need to be observed.
Which AC sine wave term is defined as being "360 degrees and the result of one revolution of an AC generator"?
Cycle
What does the letter "K" represent in reference to a capacitor?
Dielectric constant
In an AC circuit what formula(s) are used to find apparent power (VA)?
E x I
A circuit is considered inductive if the henry's are greater than the farads.
False
A series RLC circuit is resonant when henrys = farads.
False
A single cycle of an AC sine wave consists of only a positive half cycle.
False
The period of an AC sine wave is measured in units of degrees.
False
The voltage drop across a capacitor of an RLC circuit can be found by the formula: EC=It×C
False
When a circuit is capacitive, the theta will be a positive angle.
False
Inductance is measured in units of _________.
Henrys
In an AC circuit what formula(s) are used to calculate true power (wattage)?
I^2 (R) E^2 / R
When would inductive reactance be lowest?
In a low frequency circuit.
Select all of the below that would result in an increased output of an AC generator.
Increase number of conductors. Increase the rate of cutting magnetic lines of flux. Increase magnetic flux.
Select the values that are needed to be known to calculate a circuit's resonant frequency.
Inductance in henry's. Capacitance in farads.
In a "real world" application, if an inductor is placed into an AC circuit what opposes current flow?
Inductive reactance and resistance.
If the area of the plates of a capacitor were reduced what would happen to capacitance?
It would decrease.
What is inductive reactance (XL)?
The opposition to the flow of AC given by an inductor.
The symbol used to represent phase angle is _____.
ThetaΘ
A micro-farad capacitor's value would be 10^−6 farads.
True
All of the below values can be plugged into the "R" section of Ohm's Law because they are all in units of ohms: Resistance (R) Inductive Reactance (XL) Capacitive Reactance (XC) Impedance (Z)
True
Although they are technically not inductors components like those listed below exhibit some of the characteristics of an inductor: Relay and solenoid coils Motors Generators
True
An RLC circuit will consist of the below components: Capacitor(s) Resistor(s) Inductor(s)
True
As the armature of an AC generator rotates through a magnetic field, its output polarity will change resulting in the flow of current to reverse.
True
Because inductive reactance is measured in ohms, it can be plugged into Ohm's Law in the same section of the formula as resistance.
True
Capacitors are said to block DC current.
True
Capacitors in an AC circuit will charge one-way, discharge, and charge in the opposite direction. This occurs during each half-cycle of the AC sine wave.
True
In a circuit with both resistance and capacitance (RC), if the frequency increases the capacitive reactance (Xc) will decrease.
True
When a circuit is inductive, the theta will be a positive number.
True
Which form of power in an AC circuit actually results in work?
True
In a circuit that only has inductance, what is the relationship of the voltage and the current?
Voltage leads the current by 90 degrees.
What is the relationship of voltage and current in an inductor?
Voltage leads the current.
Which AC sine wave term is defined as "the maximum value of a half cycle"?
Vp
Which AC sine wave term is defined as the "maximum difference between the positive and negative peaks of the sine wave"?
Vpp
An AC sine wave voltage is said to be 28VAC. The voltage is assumed to be _____.
Vrms
A circuit is resonant when _____.
XL = XC
Total reactance in a series circuit is found by _____.
XT = XL-XC
An increase in inductive reactance would result in _____.
a decrease in total circuit current.
The rotating conductor coil in an AC generator is called the _____.
armature
Inductive reactance can be determined by _______.
calculation
Theta is measured in units of _____.
degrees
When a wire is moved through a magnetic field, or a magnetic field is moved across a conductor, voltage is induced into the conductor through _________.
electromagnetic induction.
The capacitor stores the electrical charge in the form of an _____ between its plates.
electrostatic field
As frequency increases, the wavelength of an AC sine wave ______.
goes down.
AC generators convert _____ to electrical energy.
mechanical energy
The wavelength of an AC sine wave is measured in units of _____.
meters
Capacitive reactance (XC) is measured in units of _____.
ohms
Total circuit reactance (XT) is measured in units of _____.
ohms
The time to complete one cycle of an AC sine wave is its _____.
period
The opposition to the flow of current as a result of inductance is called _____.
reactance
At resonance, the circuit will appear to be _____.
resistive
The effective value of an AC sine wave is also known as it _____ value.
root-mean-squared
Phase angle (theta) is _____.
the electrical degrees that voltage leads, or lags, the current.
A circuit has 3 capacitors connected in parallel. If a fourth capacitor is connected in parallel the _____.
total capacitance will increase.
The physical length of one complete cycle of an AC sine wave is its _____.
wavelength
What would the expected circuit power factor be at resonance?
100%
Which power factor reflects a circuit with the most efficient use of electrical energy?
100%
Occasionally, a capacitor's value may be in in nano-farads. This would be _____ farads.
10^−9
How many half cycles are in one complete AC sine wave cycle?
2
Select the degrees of AC generator armature rotation where maximum induced current occurs.
270 degrees 90 degrees
How many factors oppose current in an RLC circuit?
3
It takes _____ time constants to fully charge a capacitor. (enter only the numeric value rounded to 3-decimal places if necessary)
5
According to the FAA, a capacitor's working voltage must be at least _____ % higher than the highest applied voltage. (enter only the numeric value rounded to 3-decimal places if necessary)
50
Half rotation of an AC generator produces one complete AC sine wave output.
False
In a purely resistive circuit, voltage leads the current by 180 degrees.
False
The henrys of an inductor change with frequency.
False
The opposition that resistance, inductive reactance, and capacitive reactance give to the flow of current is measured in units of _____.
Ohms
In which type of circuit is the voltage and current in-phase (theta = 0.0)?
Purely resistive.
Select the below factors that are part of "impedance" in a RLC circuit.
Resistance Capacitive reactance Inductive reactance
In a purely capacitive circuit, current leads the voltage by 90 degrees.
True
Inductive reactance only exists when the current is changing.
True
Non-polarized capacitor are safe to install into AC circuits.
True
The Vp of an AC sine wave is one half of its Vpp.
True
The phase angle of an AC sine wave is the "angle in degrees that the voltage either leads or lags the current."
True
The simplest description of an inductor is it being a coil of wire.
True
The voltage drop across and inductor can be found by using the below formula: EL=It×XL
True
Total current in an RLC circuit can be found by the below formula: It=Et/Z
True
Unlike a DC circuit, in an AC circuit the voltage and current can be out of phase with each other.
True
Which AC sine wave term is defined as "the value of AC that will result the same amount of heat in a resistor as a DC of the same value"?
Vrms
Which AC sine wave voltage value is 70.7% of the peak value?
Vrms
The greater the inductance of an inductor the ______.
greater it opposes changes in current.
The frequency of an AC sine wave is measured in units of _____.
hertz
When the three factors of R, XL, and XC are combined into one value it is called _____.
impedance
Adding an inductor in series with another inductor would result in _____.
increased inductive reactance.
Frequency and period have a(n) _____ relationship.
indirect
The amount of capacitance a capacitor has is dependent on three things. These three things are _____.
plate area, dielectric, and plate separation.
Inductors utilize a type of electromagnetic induction called _____.
self induction.
When a capacitor is in a DC circuit it will eventually charge to the value of the source voltage. When it reaches full charge current flow will _____.
stop.
When a series RLC circuit is resonant, the circuit will be resistive and have a power factor of approximately 100%. This would indicate that all of the source energy is going into _____.
true power (W).
The magnetic lines of flux around an inductor are sometimes concentrated by ________.
using a ferrous material core.
When a series RLC circuit is at resonance, what is the theta of voltage a current?
Approximately 0.0 degrees.
What characteristic of a capacitor opposes the flow of current?
Capacitive reactance
