FEE Flashcards - Intro to AC Circuits (2)

Question 1

A signal that has the form of the sine or cosine function

Answer 1

Sinusoid

Question 2

a sinusoidal current is usually referred to as ___

Answer 2

alternating current (AC)

Question 3

This current reverses at regular time intervals and has alternately positive and negative values.

Answer 3

Alternating Current (AC)

Question 4

Circuits driven by sinusoidal current or voltage sources

Answer 4

AC Circuits

Question 5

In what ways do electricity flow

Answer 5

Direct Current (DC) Alternating Current (AC)

Question 6

Difference between AC and DC in flow of eelctrons

Answer 6

DC: electrons move forward AC: Electrons switches forward and backward

Question 7

Difference between AC and DC in cause of direction of elections

Answer 7

DC: Steady magnetism along the wire AC: Rotating magnet along the wire

Question 8

Difference between AC and DC in Current

Answer 8

DC: Current is constant AC: Current varies with time

Question 9

Difference between AC and DC in amount of energy carried

Answer 9

DC: Voltage cannot travel far AC: Safe to transfer over longer city distances

Question 10

Difference between AC and DC in Frequency

Answer 10

DC: Frequency of current is 0 AC: 50 or 60Hz depending on the country

Question 11

Where are AC and DC obtained from

Answer 11

DC: Cell or Battery AC: AC generator and mains

Question 12

Passive parameters of AC and DC

Answer 12

DC: Resistance AC: Impedance

Question 13

Power factors of AC and DC

Answer 13

DC: Always 1 AC: Between 0 and 1

Question 14

the ratio of the real power that is used to do work and the apparent power that is supplied to the circuit.

Answer 14

Power Factor

Question 15

Alternating voltage may be generated by?

Answer 15

(a) by rotating a coil in a magnetic field or (b) by rotating a magnetic field within a stationary coil

Question 16

the resulting graph of an alternating current plotted to a base of time.

Answer 16

Waveform

Question 17

It also refers to a time-varying waveform known as a sinusoidal wave or a generated sine wave.

Answer 17

AC Waveform

Question 18

Types of Waveform

Answer 18

sinusoidal wave, Half wave, Triangular wave, Semi-circular wave, Trapezoidal wave, Square wave

Question 19

One complete series of values

Answer 19

Cycle

Question 20

One complete cycle is equivalent to

Answer 20

1 revolution

Question 21

The time taken in seconds for an alternating quantity to complete one cycle

Answer 21

Period or Periodic Time (T)

Question 22

Electromagnetic Induction formula

Answer 22

E(emf) = -N(dΦ/dt)

Question 23

Time period formula

Answer 23

T = 2π/ω or T = 1/f ; ω: Angular Velocity in rad/s

Question 24

Angular Velocity (ω) formula

Answer 24

ω = 2πf

Question 25

The number of cycles completed per second

Answer 25

Frequency (f)

Question 26

The standard frequency of the electricity supply in the Philippines

Answer 26

60 Hz

Question 27

Frequency (f) formula

Answer 27

f = PN/120 or f = 1/T ; P: No. of pole/s ; N: speed in rpm ; T: Time in seconds

Question 28

the voltage produced when a conductor winding in a magnetic field or by altering the direction of flux

Answer 28

emf

Question 29

This is largest value reached in a half cycle (during positive or negative) of the waveform.

Answer 29

Max Value (or peak/crest value)

Question 30

This is the average value measured over a half cycle

Answer 30

Ave Value (or mean value)

Question 31

form factor formula

Answer 31

ff = rms/ave

Question 32

peak factor

Answer 32

pf = max/rms

Question 33

This is the current which will produce the same heating effect as an equivalent direct current

Answer 33

Effective (rms) value

Question 34

It is sometimes called as root mean square (rms) value and whenever an alternating quantity is given, it is assumed to be the rms value

Answer 34

Effective value

Question 35

For sine wave, form factor is equivalent to ___ while ___ for the peak factor.

Answer 35

1.11 ; 1.41

Question 36

rms formula in sine wave

Answer 36

rms = max/√2

Question 37

ave formula in sine wave

Answer 37

ave = 2max/π

Question 38

the values of the alternating quantities at any instant of time or angle of rotation. They are represented by small letter.

Answer 38

Instantaneous values

Question 39

sinusoidal voltage formula

Answer 39

e = Emsin(wt + θ)

Question 40

sinusoidal current formula

Answer 40

i = Imsin(wt + θ)