Here's why:
* Different speeds: Waves travel at different speeds in different media. For example, light travels slower in water than in air.
* Change in direction: When a wave enters a new medium at an angle, one side of the wavefront enters the new medium before the other side. This causes the wavefront to bend, resulting in a change in the direction of propagation.
Snell's Law describes this relationship mathematically:
```
n1 * sin(θ1) = n2 * sin(θ2)
```
where:
* n1 and n2 are the refractive indices of the two media
* θ1 is the angle of incidence (angle between the incoming wave and the normal to the boundary)
* θ2 is the angle of refraction (angle between the refracted wave and the normal to the boundary)
Key Points:
* Angle of incidence and refraction: The angle of incidence and the angle of refraction are related, but not always equal.
* Speed and wavelength: The speed and wavelength of the wave also change when it enters a new medium.
* Total internal reflection: If the angle of incidence is large enough, the wave may be totally reflected back into the original medium.
Examples:
* Light refracting through a prism: This is a common example of refraction, where light bends as it passes from air into glass.
* Sound waves refracting through different layers of air: Sound waves travel at different speeds through warm and cold air, causing them to bend and creating phenomena like mirages.
Let me know if you'd like to explore specific examples or dive deeper into the physics of refraction!
