He succeeded in producing electromagnetic waves, and confirmed Maxwell's ... Among contemporary developments in radio is Digital Audio Broadcasting, or DAB. In the works since the late 1980s ...

Ultrasound travels at the speed of sound which is 330 m/s in air. This is not fast enough to track fast moving aircraft or more distant objects. So, instead of using ultrasound, radio waves are ...

For water waves and sound waves the unit hertz is usually good enough but radio and TV waves have such a high frequency that the kilohertz (\(kHz\)) or even the megahertz (\(MHz\)) are better units.

The difference is in how the carrier wave is modulated, or altered. With AM radio, the amplitude, or overall strength, of the signal is varied to incorporate the sound information. With FM ...