You searched for: “electromechanical chopper
electromechanical chopper, contact modulator (s) (noun); electromechanical choppers, contact modulators (pl)
A switch that is used to produce modified square waves having the same frequency as, and a definite phase relationship to, a driving sine wave or a waveform with deviation that can be graphically expressed as the sine curve or a form or shape of a wave (a ripple or undulation).

All electromagnetic radiation, including radio signals, light rays, x-rays, and cosmic rays, as well as sound, behave like rippling waves in the ocean.