Frequency
Frequency is the number of cycles of the waveform in one second. Frequency is calculated as the reciprocal of ('one divided by') the time for one cycle, the period, \(T\).
This relationship is shown by the equation \(f= \frac {1}{T}\)
Frequency is measured in Hertz, Hz.
Period is measured using the 'timebase' (seconds per division) from the oscilloscope controls.
For example, to determine the frequency of the trace shown in the diagram, the signal takes four divisions for one full cycle (an example of one cycle is highlighted in yellow).
The timebase is set to two milliseconds (0.002s) per division.
Periodic time for one cycle = divisions x timebase
\(T=4 \times 0.002\)
\(T= 0.008s\)
Frequency, \(f= \frac {1}{T}\)
So \(f= \frac{1}{{0.008}}\)
\(f= 125 Hz\)
Care needs to be taken to count the number of divisions carefully and use the correct units when determining frequency.
Question
If the frequency of the applied voltage was changed to 250 Hz, describe what would be seen on the oscilloscope screen?
Twice as many cycles would be seen with peaks closer together. The height would not change as the voltage has not been changed.
