AC Theory
What has the ability to store an electrical charge?
Capacitance
What prevents the Simpson 260 from reading DC voltage on the "output" scale?
Capacitor
Will Increasing the distance between the plates of a capacitor INCREASE or DECREASE its total capacitance?
Decrease
What is the insulator which separates the conductors in a capacitor?
Dielectric; made of air, oil, or ceramic
What is the unit of measurement for capacitance?
Farad
What is the equation for resonant frequency?
Fr=1/2(Pi)(SquareRoot)LC
What is the unit of measurement of inductance?
Henry
Will increasing the size of a capacitor's plate area INCREASE or DECREASE its total capacitance?
Increase
Will DECREASING or INCREASING the size of a capacitor or inductor will decrease the resonant frequency of a tuned shunt?
Increasing
Does a relay operate on the property of INDUCTANCE or CAPACITANCE?
Inductance
What has the opposition to change in current?
Inductance
Because the track circuit contains INDUCTIVE or CAPACITIVE reactance, a high frequency overlay will be shorter length than a low frequency overlay?
Inductive
Will two capacitors connected in series possess MORE or LESS capacity than if connected in parallel? Why?
Less; because total capacitance is smaller than the smallest in series, and total capacitance in parallel will add. Ct=KA/D
What is reactance?
Opposition to AC offered by inductors and capacitors
What is resonance?
Resonance occurs in an electric circuit at a particular resonance frequency when the imaginary parts of impedances or admittances of circuit elements cancel each other
Will shunting a track circuit with no relay-end resistor cause the relay to drop FASTER or SLOWER than a track circuit which includes a relay-end resistor?
Slower. TC=L/R
What is inductive reactance?
The opposition to a change in current in an AC circuit caused by the build and collapse of the electromagnetic field, and will cause a phase shift in the voltage across the inductor. Xl=2(Pi)fl
What is capacitive reactance?
The opposition to a change in voltage in an AC circuit caused by the charge and discharge of the static field, and will cause a phase shift in the voltage across the capacitor. Xc=1/2(Pi)fc
What is impedance?
The total opposition to a current flow in a circuit. It is the vector sum of the resistance and reactance of a circuit. Z=(SquareRoot)R(2)+(XL-XC)(2)
What is a capacitor?
Two conductors separated by a dielectric mad of air, oil, or ceramic that resists a change in voltage. Capacitors can store an electric static charge.
How does a capacitor oppose a change in voltage?
By causing a charge and discharge of a static field, which causes a phase shift in the voltage across the capacitor
How does an inductor oppose a change in current?
By the cause of a build and collapse of a electromagnetic field, which causes a phase shift in voltage across the inductor
What is an inductor?
A coil of wire that resists change in current and operates off of electromagnetic fields as a principle
What effect does increasing the frequency of a signal applied to an inductor have on inductive reactance?
It will increase the inductive reactance
What effect does increasing the frequency of a signal applied to a capacitor have on capacitive reactance?
It will lower the capacitive reactance
Will two inductors connected in series possess MORE or LESS inductance than if connected in paralles? Why?
MORE, Total inductance in series adds, and the total inductance is smaller than the smallest in parallel. Ct=KA/D
