Sound waves can be classified into four main types based on their behavior and interaction with the medium they travel through. These are:
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### 1. **Longitudinal Waves**
- **Characteristics**:
- The particle displacement in the medium is parallel to the direction of wave propagation.
- Composed of compressions (areas of high pressure) and rarefactions (areas of low pressure).
- **Example**: Sound traveling through air or water. Vibrating air molecules oscillate along the same direction as the wave movement.
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### 2. **Transverse Waves**
- **Characteristics**:
- The particle displacement in the medium is perpendicular to the direction of wave propagation.
- Often visualized as up-and-down oscillations relative to wave travel.
- **Example**: Although most sound waves in fluids (air, liquids) are longitudinal, sound waves in solid materials can sometimes behave as transverse waves.
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### 3. **Surface Waves**
- **Characteristics**:
- A combination of longitudinal and transverse wave motions.
- Occur at the interface between two different media, such as air and water.
- Particles move in circular or elliptical paths.
- **Example**: Ocean waves and seismic waves on the Earth's surface.
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### 4. **Stationary Waves (Standing Waves)**
- **Characteristics**:
- Formed by the superposition of two waves traveling in opposite directions with the same frequency and amplitude.
- Do not travel through the medium; instead, they create nodes (points of no displacement) and antinodes (points of maximum displacement).
- **Example**: Sound waves in a musical instrument like a guitar string or a flute.
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### Summary Table:
| **Wave Type** | **Direction of Particle Motion** | **Medium** | **Examples** |
|-----------------------|---------------------------------------|--------------------|-----------------------------------------|
| Longitudinal | Parallel to wave direction | Air, water | Speech, music through air |
| Transverse | Perpendicular to wave direction | Solids | Vibrations on a stretched string |
| Surface | Circular or elliptical paths | Interface (e.g., air/water) | Ocean waves, seismic surface waves |
| Stationary (Standing) | Varies based on nodes/antinodes | Solids, gases | Musical instruments, sound in a tube |
Each type of sound wave arises from specific conditions and interactions, playing a vital role in understanding acoustics and wave mechanics.