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The value of form factor is
0
1
1.11
2.22
0
Quick Summary: The form factor of an alternating current waveform is defined as the ratio of its Root Mean Square (RMS) value to its Average value. For a pure sinusoidal waveform, this ratio is mathematically constant at approximately 1.11.
The form factor of an alternating current waveform is defined as the ratio of its Root Mean Square (RMS) value to its Average value. For a pure sinusoidal waveform, this ratio is mathematically constant at approximately 1.11.
Kf=VavgVrms — Definition of Form Factor
Kf=22π≈1.11 — For pure sinusoidal waveform
For a sine wave with peak value Im, the RMS value is 2Im and the average value (over half cycle) is π2Im. Calculating the ratio: Form Factor=AverageRMS=2Im/πIm/2=22π≈1.11. This factor is critical for characterizing the shape of periodic electrical waveforms.
Form factor depends purely on the waveform shape, not the magnitude or frequency.
A form factor of 1.11 is the standard calibration reference for most AC meters.
A square wave has a form factor of 1.0 since RMS equals Average value.
Provides a simple coefficient to describe waveform distortion.
Useful for calculating the reading errors in non-true RMS measuring instruments.
Only strictly 1.11 for pure sinusoidal waves; distorted waves will yield different values.
Cannot be used to determine peak voltage without the peak factor.
AC motor and generator design analysis.
Calibration of AC voltmeters and ammeters.
If the waveform is not sinusoidal, the form factor will differ from 1.11.
Option A (0) is physically impossible for any real periodic signal. Option B (1) is the form factor for a square wave.
C is correct — The form factor of a sinusoidal alternating current is the ratio of RMS value to average value, which evaluates to approximately 1.11.
Remember that Form Factor is RMS/Avg (1.11) and Peak/Crest Factor is Peak/RMS (1.414) for sine waves; these are frequently tested in engineering exams.