3311701 SEM: 1 BI
IC DEPARTMENT
GOVERNMENT POLYTECHNIC GANDHINAGAR 1
PRACTICAL: 10
AIM: Obtain various parameters related to given A.C. waveform.
APPARATUS: Function Generator
CRO
CRO Probes
THEORY:
Whether the waveform is uni-directional, bi-directional, periodic, non-periodic, symmetrical,
non-symmetrical, simple or complex, all electrical waveforms include the following three
common characteristics:
Period: – This is the length of time in seconds that the waveform takes to repeat itself
from start to finish. This value can also be called the Periodic Time, (T) of the waveform
for sine waves, or the Pulse Width for square waves.
Frequency: – This is the number of times the waveform repeats itself within a one second
time period. Frequency is the reciprocal of the time period, (ƒ = 1/T) with the standard
unit of frequency being the Hertz, (Hz).
Amplitude: – This is the magnitude or intensity of the signal waveform measured in volts
or amps.
Periodic waveforms are the most common of all the electrical waveforms as it
includes Sine Waves. The AC (Alternating Current) mains waveform in your home is a sine
wave and one which constantly alternates between a maximum value and a minimum
value over time.
The amount of time it takes between each individual repetition and cycle of a sinusoidal
waveform is known as its “periodic time” or simply the Period of the waveform. In other
words, the time it takes for the waveform to repeat itself.
Then this period can vary with each waveform from fractions of a second to thousands
of seconds as it depends upon the frequency of the waveform. For example, a sinusoidal
waveform which takes one second to complete its cycle will have a periodic time of one
second. Likewise a sine wave which takes five seconds to complete will have a periodic
time of five seconds and so on.
