__Properties of Waves:__

**1. Phase:** The quantity from which the motion of a wave can be known completely is called the **phase** of the wave.

**2. Complete Wave:** The wave in between two consecutive particles, having the same phase at an instant is known as a **complete wave**.

**3. Wavelength:** The length of a complete wave, the distance between two consecutive particles having the same phase at an instant is called the **wavelength (λ)**.

**4. Time Period:** Time required to form a complete wave, the time taken by a wave to cover a distance between two consecutive particles having the same phase of vibration is called the **time period**.

**5. Frequency:** Frequency (n) of a wave is the number of complete waves formed in unit time.

**6. Amplitude of a Wave:** The amplitude of a wave is the maximum displacement of any particle producing the wave, from its mean position.

**7. Wave Velocity:** Distance traveled by a wave in a unit of time is called its **wave velocity (V)**.

**8. Wavefront:** All the particles on a surface normal to the direction of propagation of a wave have the same phase. A surface of this type is called a wavefront.

In other words, the wavefront is the locus of all points having the same phase of motion at the same instance of time. This surface is perpendicular to the direction of propagation of wave at any point.

**9. Ray:** A normal drawn on a wavefront is called a **ray**.