Why do radio waves travel at the speed of light and not sound?

There are two key points that may cause confusion: (visible) light and radio waves are both electromagnetic radiation;; radio stations do transmit radio waves, but they're not sound waves; they're electromagnetic waves. Radio waves and light are both part of the electromagnetic spectrum. source: nasa.gov. read more

As such, they travel at the speed of light (ie 300,000 kilometres/186,000 miles per second) – a lot faster than the 340 metres (1,125 feet) per second that sound itself moves through the air. read more

Radio waves are electromagnetic waves and do not require a physical medium to travel (or propagate). So, like all EM waves, they travel at the speed of light, c. Sound waves are a type of matter wave in the sense they are compressions and rarefactions of the medium (solids, liquids, and gases) they travel in. read more

If the frequency of the light is the same as the resonant frequency of the electrons, the material is opaque. You can get sunburnt on a cloudy day, but you can't get a sunburn even on a sunny day if you are behind glass. read more