# Form factor and peak factor of rectifier

##### Peak factor

The peak factor is defined as the ratio of the maximum value to the RMS value of an alternating quantity.

Peak factor = Peak value / RMS value

RMS voltage of a half wave rectifier, VRMS = Vm/2. Where Vm is the Maximum or peak voltage.

Then the Peak factor of a half wave rectifier  can be calculated as,

Vm / VRMS = Vm / ( Vm / 2 ) = 2 Vm / Vm = 2

Similarly, For a full wave rectifier, the RMS voltage VRMS = Vm / √2

Therefore, the Peak factor value of a full wave rectifier = Vm / Vm/ √2

= Vm √2 / Vm = √2 = 1.414

##### Form factor

The ratio of RMS value to the average value of an alternating quantity is known as its form factor.

Form factor = RMS value / Average value

RMS voltage of a half wave rectifier, VRMS = Vm / 2 and Average Voltage  VAVG= Vm/π,  Vis the peak voltage.

Form factor of a half wave rectifier = VRMS / VAVG = ( Vm /2 ) / ( Vm / π )

= π Vm / 2 Vm = 1.57

For a full wave rectifier, the RMS voltage VRMS = Vm / √2 and the average Voltage,

VAVG = 2 V/ π

Form factor value of a full wave rectifier = ( Vm / √ 2 ) / ( 2Vm / π )

= π Vm / 2√2  Vm = 1.11

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