– What are oscilloscopes measuring, exactly? I know the y-axis is voltage and the x-axis is time, but what does that mean? How can they display, say, sound waves? What does sound have to do with voltage?

Question

Also, if you plug a probe into it then to an outlet, what is the oscilloscope displaying? The difference in electric potential between what?

In: 0

Answer 1

In normal use the x axis indeed is time based.

The input to the Y axis has to be a voltage. You can measure many different types of signal (sound, temperature, current… blah blah) BUT you need to convert it to a voltage first.

In the case of sound – you are probaly happy with using a microphone.. this converts sound into an analog voltage which could be fed to an amplifier to hear it – OR to to a scope in which case the Y axis will be scaled for amplitude, and the X will give an indication of frequency.

Other examples –

a thermocouple provides a voltage signal based on temperature

a pressure sensor gives signal based on pressure..

most sensors provide a voltage output based on some physical input….

As for your probe – it probably has a shield or ‘ground’ clip associated with it. The voltage is normally refernced to this, or to the 0V of the scope power.