Sound is a form of energy that travels through a medium (such as air, water, or solid objects) in the form of waves. It is produced when an object vibrates, causing disturbances in the surrounding medium, which our ears perceive as sound.
1. How is Sound Produced?
When an object vibrates, it causes the surrounding particles to vibrate as well. These vibrations create regions of compression and rarefaction, forming sound waves that travel through the medium.
Examples:
When you pluck a guitar string, it vibrates and produces sound.
When we speak, our vocal cords vibrate to generate sound waves.
2. Nature of Sound
Sound is a mechanical wave, meaning it requires a medium to travel. Unlike light, it cannot propagate through a vacuum.
There are two main types of sound waves:
1. Longitudinal Waves: In these waves, the particles of the medium vibrate parallel to the direction of wave propagation (e.g., sound traveling in air).
2. Transverse Waves: In these waves, the particles vibrate perpendicular to the direction of wave propagation (e.g., water waves). However, sound in air is always longitudinal.
3. Properties of Sound
Sound has several important properties:
(a) Frequency (Pitch)
The number of vibrations per second is called frequency, measured in Hertz (Hz).
Higher frequency = higher pitch (e.g., a whistle).
Lower frequency = lower pitch (e.g., a drum).
(b) Amplitude (Loudness)
The greater the amplitude, the louder the sound.
Measured in decibels (dB).
A whisper is around 20 dB, while a jet engine is about 120 dB.
(c) Wavelength
The distance between two successive compressions or rarefactions in a sound wave.
It determines the pitch and energy of the wave.
(d) Speed of Sound
The speed of sound depends on the medium:
In air: ~343 m/s