Question

The waveform of a certain signal can be studied by

Answer 1

Waveform is any shape or form of a signal of a wave moving in a physical medium or an abstract representation. To be more specific, a waveform is depicted by a graph that shows changes in a recorded signal's amplitude over the duration of recording. 

To study a certain signal of waveform, as instrument called oscilloscope is used to pictorially represent a wave as a repeating image on a screen.