The CRO is the electrical and electronic engineer's best
friend. So it's worth getting to know the instrument.
The CRO is connected in exactly the same way as a
voltmeter, i.e. in parallel with a component.
This is a typical display of a sinusoidal waveform on
the CRO screen:
The screen has a grid of 1
cm squares and the y-gain is marked in volt cm-1. The
time-base is marked in ms cm-1 or
This CRO screen shows the idea:
The horizontal scale is the
time period, measured in seconds, or, more usually, in
1 ms = 1 × 10-3 s
We count how many squares
there are on the horizontal axis, then calculate the time by
multiplying the number of squares by the time per square.
T = length (cm) ×
time-base (s cm-1)
This time is the period. To get the frequency,
we need to take the reciprocal of the period.