The speed of light in a vacuum, denoted by the symbol "c," is approximately 299,792,458 meters per second (m/s) or about 299,792 kilometers per second (km/s). This is a fundamental constant in physics and plays a crucial role in the theory of special relativity.
On the other hand, the speed of sound, denoted by the symbol "v," depends on the medium through which it travels. In air at room temperature, the speed of sound is approximately 343 meters per second (m/s) or about 1,235 kilometers per hour (km/h). The speed of sound varies in different materials; for example, it is faster in water and even faster in solids like steel.
In comparison, other electromagnetic waves, such as radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays, all travel at the speed of light in a vacuum (c). However, their wavelengths and frequencies differ, which is what gives rise to their distinct properties and interactions with matter.
To summarize:
- Speed of light in a vacuum (c) ≈ 299,792,458 meters per second (m/s).
- Speed of sound in air (at room temperature) ≈ 343 meters per second (m/s).
- Speed of other electromagnetic waves (e.g., radio waves, visible light) = Speed of light in a vacuum (c). The only difference is in their respective wavelengths and frequencies.
In everyday experiences, the speed of light is significantly faster than the speed of sound. For example, light from the Sun takes about 8 minutes and 20 seconds to reach the Earth, while sound from a nearby thunderstorm is heard almost instantly. This is why we often see lightning before hearing the associated thunder.