1. AC Wavefrom – The AC Waveform
The waveform of an alternating current generally follows the sine function
and is known as ‘sinusoidal’. It is stated as being alternating because it
changes polarity every half-cycle.
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360
Peak-to-Peak
Peakvalue
1 cycle
Ø degrees

2. -1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
r.m.s. value
0.707xpk
0 5 10 15 20 time
(ms)
periodic time
T = 1/ frequency
AC Wavefrom – The AC Waveform
When the frequency is known the x-axis can be scaled in units of time. The
example below is scaled for a frequency of 50Hz.
The frequency of a waveform is the number of complete cycles in one
second.

3. AC Waveform – The AC Waveform
A circle is usually expressed in terms of degrees however when working with
electrical waveforms it is more common to use the Radian.
0° or 2π radian180° or π radian
2
90° or π radian
2
270° or 3π radian
ω rad/s
Angular Velocity

4. AC Waveform – The AC Waveform
A point rotating in a counter-clockwise direction can be plotted on an x/y axis
to produce a sinusoidal waveform.
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 deg
0° / 360°
2π rad
180°
π rad
2
90°
π rad
2
270°
3π rad
Ø
r
r sinØ