AC Electricity

Resonance

A frequency in an given RLC AC circuit at which the capacitive reactance is equal to the inductive reactance

AC Average Voltages

The averaging of all the values along the time axis with time being in full period

Variable Caps

change capacitance by changing area of plate (Dielectric in variable cap is usually air)

How many degrees of rotation are there in one cycle of AC?

360 degrees

Capacitor

A device used to store electrical energy in the form of electrostatic fields. A capacitor is essentially two conductors separated by an insulator

Name three common AC wave forms

Sine Wave Square Wave Rectangle Wave

How many alterations are there in a cycle of AC?

2 alternations

What is the period for an AC waveform with a frequency of 400 Hz?

2.5ms

How many cycles of AC are there in 400 Hz?

400 cycles

What is the frequency of AC that has a period of 1/60 per second

60 Hertz

Amount of time required for capacitor to charge to

63.2 of max "E" T=RC

What is the effective voltage of AC that has a peak value of 100 volts?

70.7V

How many times will current change/reverse direction in an AC waveform that has a frequency of 400 Hz?

800 times

How many degrees of phase difference exist between voltage and current in an AC circuit that is purely capacitive?

90 degrees leading

Farad

A basic unit of capacitance. A capacitor of one farad will hold one coulomb

AC Cycle

A complete negative and positive wave of alternating current

Hertz

A unit for measuring the frequency of vibrations or of AC electricity

Capacitor blocks DC while passing

AC

Inductor

An inductor is a passive electronic component that stores energy in the form of a magnetic field

Inductive Reactance

An opposition to the flow of AC caused by generation of an induced voltage whose polarity is opposite to that of the voltage that created it

State Ohms law for an AC circuit

Current in an AC circuit is directly proportional to voltage and inversely proportional to impedance

How many degrees of phase difference exist between voltage and current in an AC circuit that is purely inductive?

Current lags voltage by 90 degrees

AC Effective Voltages

DC voltage that would produce the same amount of heat in a resistor

Permittivity is called

Dielectric constant

Define AC

Electricity that continuously changes in magnitude and periodically in direction

Capacitor uses

Filtering AC Smoothing DC ripple Electrical coupling in radio circuits Tuning Timing Circuits

Two types of caps

Fixed caps Variable caps

Cap materials

Glass, ceramic, plastic film, air, vacuum, paper, mica, and oxide layers

Does current lead or lag voltage in an AC circuit that is purely inductive?

Lags

Does current lead or lag voltage in an AC circuit that is purely capacitive?

Leads

Does current lead or lag voltage in an AC circuit that is purely resistive?

Neither, they are in phase

What factors affect the inductance of an inductor?

The number of turns in the coil, the diameter of the coil, coil length, and material used

Apparent Power

The product of RMS current and RMS voltage expressed in volt-amperes

Reactance

The relative difficulty with which magnetic domains can be aligned and the opposition to magnetic flux

Henry

The standard unit of inductance. It is the amount of inductance in which a current change of one ampere per second will induce a voltage of one volt

RMS

The value of direct current equivalent to an alternating current sine wave

Impedance

The vector sum of the opposition to the flow of AC caused by circuit resistance, capacitive reactance, and inductive reactance

Sinewave

The wave form of AC produced by a rotary generator. Its amplitude id proportional to the sine of the angle through which the generator is turned

Induction

The wireless transfer of energy

What is the relationship between capacitive reactance and inductive reactance in a resonant AC circuit?

Their relationship depends on their phase. The phase relationship between voltage and current in an AC capacitance circuit is the exact opposite to that of an AC inductance circuit

What is the purpose of a capacitor?

To store electrical energy in an electrostatic field

In an AC circuit a capacitor drops voltage and shifts the phase of current

but does not consume power or produce heat

(True or False) Apparent Power equals True power in a resonant AC circuit

True

One farad is the capacity required to hold one coloumb of electricity under

a force of one volt

electrolytic capacitor uses liquid or paste as dielectric layer when

a large amount of capacitance is required in a small physical size

The two metal plates in a conductor are superheated by a

dielectric layer

A cap is inversely proportional to the distance between its plates and

directly proportional to the size of its plates

Amount of capacitance a capacitor has is determined by the

distance between the plates size of plates dielectric type

Capacitive Reactance

is a measure of a capacitor's opposition to AC

Dielectric Permittivity is

the ease at which electrostatic lines of force can exist in an insulating material compared to a vacuum

True Power

the power that actually exists in an AC circuit. It is the product of voltage, current, and power factor or is the product of the voltage and the current that is in phase with that voltage

Frequency

the rate at which a cycle occurs or is repeated over a particular period of time or in a given sample

Power Factor

the ratio of the resistance of an electrical circuit to the circuit impedance measured by a wattmeter and in AC, the ratio of apparent power to true power