What is Cathode Ray Oscilloscope (CRO)?

A Cathode Ray Oscilloscope (CRO) is an instrument that makes use of an electron beam and a cathode ray tube to display and analyze waveforms from electrical circuits. It is basically a very fast X-Y plotter that can display an input signal versus time or another signal. The voltage and time describe a shape and are continually graphed next to a scale because the oscilloscope monitors change in electrical signals over time.

and the current i to the quantity of electricity (or charge) is given by the relation

Extra

We can examine parameters, such as amplitude, frequency, rising time, distortion, time interval, and others, by studying the waveform.