Sound and light are both forms of energy that can travel through a medium like air, but they propagate differently and at different speeds because they interact with the medium in distinct ways.
Sound is a mechanical wave, which means it requires a medium (such as air, water, or solid materials) to propagate. When a sound is produced, it creates compressions and rarefactions in the medium. In the case of air, the air particles are compressed together and then spread apart, creating a series of pressure waves that travel through the air. These pressure waves carry the sound energy from the source to our ears, allowing us to hear the sound.
The speed of sound in air (or any other medium) depends on the properties of that medium, particularly its density and compressibility. In general, sound travels faster in denser and less compressible mediums. In dry air at room temperature, the speed of sound is approximately 343 meters per second (about 1235 kilometers per hour or 767 miles per hour).
On the other hand, light is an electromagnetic wave, and it does not require a medium to propagate. It can travel through a vacuum (like outer space) as well as through a medium, such as air. Unlike sound, light does not rely on the motion of particles in the medium to propagate. Instead, it consists of oscillating electric and magnetic fields that generate self-sustaining waves.
The speed of light in a vacuum is constant and is approximately 299,792,458 meters per second (about 299,792 kilometers per second or 186,282 miles per second). When light travels through a medium like air, its speed decreases due to interactions between the light and the atoms or molecules in the medium. These interactions cause the light to be absorbed and re-emitted multiple times as it traverses the medium, resulting in a reduced net speed compared to its speed in a vacuum.
The speed of light in a medium depends on the refractive index of the material, which is a measure of how much the speed of light is reduced in that medium compared to a vacuum. In air, the speed of light is still very close to its vacuum value, with a refractive index very close to 1, so the difference is not easily noticeable to human perception.
In summary, sound and light travel through the same medium (air) but have different speeds of propagation because they are fundamentally different types of waves. Sound is a mechanical wave that relies on the motion of particles in the medium, while light is an electromagnetic wave that does not require a medium and has a constant speed in a vacuum but experiences reduced speed when passing through a medium.