1. Introduction to Characteristics of Sound
Every sound we hear has certain qualities that make it unique. These qualities depend mainly on amplitude, frequency, wavelength, and time period. Together, they decide how loud or soft a sound is, and whether it feels high or low.
2. Amplitude
Amplitude is the maximum displacement of the vibrating particle from its rest position.
It tells us how strong the vibration is. Bigger amplitude means stronger vibrations.
2.1. Effect of Amplitude
The loudness of a sound depends on amplitude. A sound with larger amplitude is louder, while smaller amplitude produces a softer sound.
2.2. Example
Plucking a guitar string lightly produces small amplitude and soft sound. Plucking it harder increases amplitude and makes the sound louder.
3. Frequency
Frequency is the number of vibrations produced in one second.
It decides whether the sound is high-pitched or low-pitched.
The unit of frequency is hertz (Hz).
3.1. Relation with Pitch
Pitch is how high or low a sound seems. Higher frequency means higher pitch, and lower frequency means lower pitch.
3.1.1. Examples
- A whistle has high frequency → high pitch.
- A drum produces low frequency → low pitch.
4. Time Period
Time Period (T) is the time taken to complete one vibration.
It is related to frequency by:
\( T = \dfrac{1}{f} \)
4.1. Understanding This
If a vibration takes a long time to complete one cycle, the time period is large and the frequency is low. If the vibration is fast, the time period becomes small and the frequency becomes high.
5. Wavelength
Wavelength (\( \lambda \)) is the distance between two consecutive compressions or two consecutive rarefactions in a sound wave.
It shows how long one wave cycle is.
5.1. Formula
Wavelength, frequency, and speed of sound are related by:
\( v = f \lambda \)
5.2. Example
If the frequency of a sound is high, its wavelength becomes shorter. That is why high-pitched sounds have closely spaced wave patterns.
6. Speed of Sound
Speed of sound is how fast the sound wave travels through a medium.
It depends on the nature of the medium—sound travels slowest in gases, faster in liquids, and fastest in solids.
7. Putting It All Together
The nature of a sound depends on how fast it vibrates (frequency), how strongly it vibrates (amplitude), how far each wave cycle spreads out (wavelength), and how fast the wave moves (speed).