V(t) = V0 sin (2πft) (set calculator to radians)
- V voltage in V
- V0 peak voltage in V
- f frequency in Hz
- t time in s
Vrms = ½ √2 V 0
- Vrms root-mean-square value of voltage
Example 1
In the drawing above.
V 0 =10 V
T = 50 ms
f = 1/T=1/(50 x 10-3) = 20 Hz
So :
V(t) = 10 sin (2π 20 t)
Vrms = ½ √2 V0 = ½ √2 ( 10) = 7.0 V
This means :
A DC voltage of 7.0 V produced the same power as an AC voltage with a peak voltage of
10.0 V
Example 2
The mains voltage is : V =230 V (This means : V rms = 230 V)
Find the peak voltage.
Vrms = ½ √2 V 0
230 = ½ √2 V 0
V 0 = 325 V