This is a topic of introductory electronics. Here’s a complete, all-embracing explanation of the CRO in just six points:

Cathode Ray Oscilloscope Explained

1. A CRO is an instrument designed to measure time intervals and voltages. It is used to display signals in electrical fault form. A non-electrical signal is required to be converted into electrical form for the display. For example: A sound wave is converted into electrical form microphone to display on a CRO.
2. Shape of the trace on screen is similar to that of input signal.
3. Time base and Y – gain are used to change the sight of trace. Y-gain is also called a voltage gain.
4. In order to measure value, the time base and Y-gain must be adjusted to have at least one complete cycle displayed on screen. If Y – gain and time base increase, the trace appears to shrink.
5. The trace displayed on the screen can be moved horizontally or vertically.
6. In order to measure DC voltages, the trace must be brought to the center of the screen with no input so that the shift determines the input voltage.