Sound and light waves are both forms of waves that carry energy, but they differ in several fundamental ways:
Nature: Sound waves are mechanical waves, which means they require a medium (such as air, water, or solids) to travel through. In contrast, light waves are electromagnetic waves that can propagate through a vacuum (like outer space) as well as through a medium.
Speed: Light waves travel much faster than sound waves. In a vacuum, light travels at a constant speed of approximately 299,792 kilometers per second (or about 186,282 miles per second), whereas the speed of sound varies depending on the medium. For example, in dry air at room temperature, sound travels at about 343 meters per second (or roughly 1,125 feet per second).
Medium of Propagation: As mentioned earlier, sound waves require a material medium to travel through, such as air, water, or solids. They rely on the vibrations of particles in the medium to transmit energy. In contrast, light waves can travel through a vacuum and do not require a material medium. They consist of oscillating electric and magnetic fields that can propagate through space.
Directionality: Sound waves are longitudinal waves, meaning the vibrations occur parallel to the direction of wave propagation. The particles in the medium move back and forth in the same direction that the wave is traveling. Light waves, on the other hand, are transverse waves, where the oscillations of the electric and magnetic fields occur perpendicular to the direction of wave propagation.
Interaction: Sound waves interact with objects by causing them to vibrate. When sound waves encounter an obstacle or a boundary, they can be absorbed, reflected, refracted, or diffracted. Light waves, on the other hand, can interact with matter in various ways, including absorption, reflection, refraction, diffraction, and interference. They can be absorbed by certain materials, reflected off surfaces, bent when passing through different mediums, and diffracted or interfered with to produce patterns.
Wavelength and Frequency: Sound waves have longer wavelengths and lower frequencies compared to light waves. The range of audible sound for humans is typically between 20 Hz and 20,000 Hz (cycles per second), while light waves have much higher frequencies, ranging from hundreds of terahertz (THz) for infrared light to hundreds of petahertz (PHz) for ultraviolet light and beyond.
In summary, sound waves are mechanical, require a medium, travel slower, and have longitudinal vibrations, while light waves are electromagnetic, can travel through a vacuum, are faster, and have transverse oscillations of electric and magnetic fields.