What is RMS (Root Mean Square) Value ?
The RMS (Root Mean Square) value (also known as effective or virtual value) of of an
alternating current (AC) is the value of direct current (DC) when flowing through a circuit
or resistor for the specific time period and produces same amount of heat which produced
by the alternating current (AC) when flowing through the same circuit or resistor for a
specific time.
What is Average Value
If we convert the alternating current (AC) sine wave into direct current (DC) sine wave
through rectifiers, then the converted value to the DC is known as the average value of
that alternating current sine wave.
What is Instantaneous Value
The value attained by an alternating quantity at any instant is known as instantaneous
value. It is denoted by “i” and e.
OR
the value of an alternating current or voltage at any particular moment us called an
instantaneous value.
What is Peak Voltage or Maximum Voltage Value ?
Peak value is also known as Maximum Value, Crest Value or Amplitude. It is the
maximum value of alternating current or voltage from the “0” position no matter positive
or negative half cycle in a sine wave. Its expressed as IM and EM or VP and IM.
Equations of Peak Voltage Value are:
VP = √2 x VRMS
Peak to Peak Value
The sum of positive and negative peak values is known as peak to peak value. Its
expressed as IPP or VPP.
Equations and formulas for Peak to Peak Voltage are as follow:
VP-P = 2√2 x VRMS
What is Peak Factor
Peak Factor is also known as Crest Factor or Amplitude Factor.
It is the ratio between maximum value and RMS value of an alternating wave.
What is Form Factor
The ratio between RMS value and Average value of an alternating quantity (Current or
Voltage) is known as Form Factor.
Other Terms Related To AC Circuits
Waveform
The path traced by a quantity (such as voltage or current) plotted as a function of some
variable (such as time, degree, radians, temperature etc.) is called waveform.
Cycle
1. One complete set of positive and negative values of alternating quality (such as voltage
and current) is known as cycle.
Time period “T”:
The time taken by a alternating quantity (such as current or voltage) to complete one
cycle is called its time period “T”.
It is inversely proportional to the Frequency “f” and denoted by “T” where the unit of time
period is second.
Mathematically;
T = 1/f
Frequency
Frequency is the number if cycles passed through per second. It is denoted by “f” and
has the unit cycle per second i.e. Hz (Herts).
The number of completed cycles in 1 second is called frequency.
f = 1/T
Amplitude
The maximum value, positive or negative, of an alternating quantity such as voltage or
current is known as its amplitude. Its denoted by VP, IP or EMAX and IMAX.
Alternation
One half cycle of a sine wave (Negative or Positive) is known as alternation which span
is 180° degree.
