AC Concepts

Combining fundamental frequency with only odd harmonics creates what type of waveform?

Square

Period formula

T= 1/f (if frequency is known, time can be calculated

Formula to calculate wavelength

300M / f

4 factors that affect the amount of EMF induced into a conductor

(CARS) 1. Conductor length within the mag field 2. Angle at which the conductor cuts through 3. Rate of speed at which the conductor is moved 4. Strength of the magnetic field

Formula to find harmonic frequencies

(Fundamental freq. hz ) * (# of harmonic freq) Ex: (20hz)(8(th harmonic)) = 160hz

Substitute variables to solve Vrms of an AC sine wave with a Vpk-pk of 12v

0.707 * 6

Vrms equation

0.707 * Vpk

A loop of wire is rotated in a magnetic field, What voltage is produced at the following sine wave locations? 0 degrees, 90 degrees, 180, 270, 360

0: 0V 90: Max positive volts 180: 0V 270: Max negative volts 360: 0V

2 advantages of AC over DC

1. DCV must be produced to the level required by the load. AC can use a transformer to step up or down voltage. 2. AC can be transmitted at a high voltage and low current levels, reducing power loss. DC transmits low voltage, high current which is dangerous and inefficient.

3 characteristics needed for sine wave calculations

1. Frequency 2. Period 3. Wavelength

3 things needed in order to produce an AC wave

1. Magnetic field 2. Conductor 3. Relative motion

Frequency formula

1/t (if period is known, frequency can be calculated)

How to calculate 8th harmonic of a 12kHz sine wave?

12k*8

An AC sine wave that has a (+) peak voltage of 7v and a (-) peak voltage of 7 has what peak to peak voltage?

14v

AC waveform is a plot of current or voltage which constantly changes in —- and —-

Amplitude / direction

Square waves can be both AC and —-

DC

What is the difference between AC and DC?

DC: current only flows in one direction - it may change magnitude (pulsating dc) - does NOT change polarity AC: current which constantly changes in both magnitude and polarity

—— ——- is an action that causes an EMF to be induced in a conductor or coil as it moves relative to a magnetic field

Electromagnetic induction

_____ is determined by the number of cycles that occur in one second

Frequency

—- frequency is the original frequency of a sine wave

Fundamental

—— frequencies are considered echoes of the fundamental frequency

Harmonic

How is period or time of a waveform defined?

How many seconds it takes for the wave to complete 1 cycle

As the speed of the generator increases, frequency (increases / decreases)

Increases

Units for wavelength

Meters / centimeters

Frequency is determined by

Number of cycles per second

When the conductor loop has completed one revolution, or 360 degrees, it has completed how many cycles of AC?

One. 1 rotation = 1 cycle AC

One cycle of AC consists of a —- and —- alternation

Positive Negative

An AC waveform is identified by having a —- and a —— alternation

Positive / negative

Combining fundamental frequency with all the harmonica creates what kind of waveform?

Ramp

Period of a sine wave is expressed as a decimal part of a —-

Second

T or F Square waveforms can be symmetrical or asymmetrical

True

If a conductor is moved through a magnetic field, a —- will be induced into the conductor

Voltage

The maximum value reached during one alternation is called

Vpk (peak voltage)

When determining circuit values in an AC circuit, what must be done first before making any other calculations?

Vpk and Vpk-pk must be converted to Vrms

A ____ is a physical activity that rises and falls periodically.

Wave

Abbreviation and unit of measurement for frequency

f Hz

Symbol for wavelength

lambda (λ)