1. Speed Change:
* When a wave (like light or sound) travels from one medium to another, its speed changes. This change in speed is because the wave interacts differently with the particles of the new medium. For example, light travels slower in water than in air.
2. Wavefront:
* A wavefront is an imaginary line connecting points of equal phase on a wave. When a wave travels in a single medium, its wavefronts move in a straight line.
3. Angle of Incidence vs. Angle of Refraction:
* The angle at which the wave hits the boundary between the two media is called the *angle of incidence*.
* The angle at which the wave continues traveling in the new medium is called the *angle of refraction*.
* If the wave slows down upon entering the new medium, it bends towards the normal (an imaginary line perpendicular to the boundary). If it speeds up, it bends away from the normal.
4. Snell's Law:
* This law mathematically describes the relationship between the angles of incidence and refraction, as well as the speeds of light in the two media.
Simple Analogy:
Imagine pushing a shopping cart on a smooth surface and then suddenly encountering a patch of grass. The wheels of the shopping cart will slow down as they enter the grass. The direction of the cart will change, bending towards the patch of grass (similar to the bending of light towards the normal).
In summary:
The bending of waves (refraction) happens because the change in speed causes the wavefronts to change direction. The degree of bending depends on the difference in the wave's speed between the two media and the angle at which it enters the new medium.
