A device that displays the continuous plot of a wave called

The correct answer is Oscilloscope.

Explanation:

An Oscilloscope is a device used to graph variable signal voltages. It can also convert to voltages and show a sound or a vibration.

What they do is show how an electrical signal changes over time. You can show the shape of a wave, by analyzing its amplitude, frequency, distortion, etc. and it can be adjusted so that we can continuously see the repetitive signals.

this device is called the Oscilloscope.