The speed of light in a vacuum is approximately 299,792,458 meters per second (or about 186,282 miles per second). The speed of sound, on the other hand, varies depending on the medium through which it travels. In dry air at room temperature, sound travels at about 343 meters per second (about 1,125 feet per second).
So, in a vacuum, light travels much faster than sound by a factor of nearly 874,030.
Despite both light and sound being forms of waves, they exhibit different behaviors because they are fundamentally different types of waves:
Nature of Propagation:
- Light: Light waves are electromagnetic waves. They are transverse waves, which means that the oscillations of electric and magnetic fields occur perpendicular to the direction of wave propagation. Electromagnetic waves can travel through a vacuum and do not require a medium.
- Sound: Sound waves are mechanical waves. They are longitudinal waves, meaning that the oscillations of particles occur parallel to the direction of wave propagation. Sound waves need a medium (solid, liquid, or gas) to travel through because they rely on the physical displacement and compression of particles in the medium.
Medium Dependency:
- Light: As mentioned earlier, light does not require a medium to propagate and can travel through a vacuum, like space. However, when light travels through different materials (e.g., air, water, glass), its speed may change due to interactions with atoms and molecules in the material, leading to phenomena like refraction.
- Sound: Sound waves, being mechanical waves, rely on the particles of a medium to propagate. The properties of the medium, such as density and elasticity, significantly affect the speed of sound. Sound waves travel faster in denser and more elastic materials, and they are slower in less dense or less elastic media.
Frequency and Wavelength:
- Light: Light waves have much higher frequencies and shorter wavelengths compared to sound waves. Visible light, for example, has frequencies ranging from hundreds of terahertz to hundreds of petahertz.
- Sound: Sound waves have lower frequencies and longer wavelengths compared to light waves. Audible sound for humans typically ranges from about 20 to 20,000 hertz.
In summary, light and sound are both electromagnetic and wave phenomena, but their fundamental nature, propagation, and speed are different due to the type of waves they are and their dependency on a medium for propagation.