In empty space, both visible light and radio waves are forms of electromagnetic radiation, but they differ primarily in terms of their wavelength and frequency.
Visible light consists of a range of wavelengths that are visible to the human eye, typically ranging from approximately 400 to 700 nanometers. The different colors we perceive, such as red, blue, and green, correspond to different wavelengths within this range.
On the other hand, radio waves have much longer wavelengths than visible light, ranging from millimeters to kilometers. They are used for various purposes, including communication, broadcasting, and radar systems. Radio waves have lower frequencies compared to visible light.
The speed of electromagnetic radiation, including both visible light and radio waves, is constant in a vacuum and is denoted by the symbol "c." In empty space, electromagnetic waves travel at the same speed, approximately 299,792,458 meters per second (or about 186,282 miles per second). This speed is independent of the wavelength or frequency of the wave.
So, to summarize, the main difference between visible light and radio waves lies in their wavelength and frequency, while their speed remains the same in empty space.