Waves and Sound
A complete physics website covering waves, sound, characteristics of waves, transverse and longitudinal waves, speed of sound, echo, resonance, Doppler effect, musical instruments, formulas, diagrams, solved examples, and exercises.
1. Waves
A wave is a disturbance that transfers energy from one place to another without transfer of matter.
Characteristics of Waves
- Amplitude
- Wavelength
- Frequency
- Time Period
2. Types of Waves
| Wave Type | Description |
|---|---|
| Transverse Wave | Particles vibrate perpendicular to direction of wave |
| Longitudinal Wave | Particles vibrate parallel to direction of wave |
3. Sound
Sound is a form of energy produced by vibrating bodies and travels through medium as longitudinal waves.
Characteristics of Sound
- Pitch
- Loudness
- Quality
4. Speed of Sound
The speed of sound depends on nature of medium and temperature.
| Medium | Speed of Sound |
|---|---|
| Air | 340 m/s |
| Water | 1500 m/s |
| Steel | 5000 m/s |
Example
Find wave velocity if frequency is 200 Hz and wavelength is 2 m.
v = 200 × 2
v = 400 m/s
5. Echo and Reverberation
The repetition of sound due to reflection is called echo.
6. Doppler Effect
The apparent change in frequency due to relative motion between source and observer is called Doppler effect.
7. Musical Instruments
| Instrument Type | Examples |
|---|---|
| String Instruments | Guitar, Violin |
| Wind Instruments | Flute, Trumpet |
| Percussion Instruments | Drum, Tabla |
8. Practice Exercises
Short Questions
- Define wave motion.
- Differentiate transverse and longitudinal waves.
- Define sound.
- What is echo?
- Define Doppler effect.
Numerical Problems
- Find wave velocity if frequency is 100 Hz and wavelength is 5 m.
- Calculate distance if echo is heard after 4 seconds and speed of sound is 340 m/s.
- Find wavelength if speed is 300 m/s and frequency is 50 Hz.
9. Formula Summary
| Topic | Formula |
|---|---|
| Wave Velocity | v = fλ |
| Echo Distance | d = vt/2 |
| Frequency | f = 1/T |