1. Change in Direction (Refraction)
* The Cause: Light travels at different speeds in different mediums. This difference in speed causes the light to bend as it enters a new medium at an angle. Think of it like a car driving from pavement onto a muddy field – its speed slows down, and it changes direction slightly.
* The Physics: Snell's Law describes this bending:
* n₁sinθ₁ = n₂sinθ₂
* n₁ and n₂ are the refractive indices of the two mediums (a measure of how much light slows down in that medium)
* θ₁ and θ₂ are the angles of incidence and refraction, respectively.
2. Change in Speed
* The Cause: Light interacts with the atoms and molecules of the medium. It gets absorbed and re-emitted, which slows it down.
* The Physics: The speed of light in a vacuum (c) is the fastest it can travel. In a medium, the speed of light (v) is less than c, and is related to the refractive index (n) by:
* v = c/n
3. Change in Wavelength (Not Always)
* The Cause: The frequency (how many wave crests pass a point per second) of light remains constant as it enters a new medium. Since the speed changes, the wavelength (the distance between wave crests) must also change to maintain the relationship between speed, frequency, and wavelength:
* v = fλ
* v = speed
* f = frequency
* λ = wavelength
* Important Note: The change in wavelength doesn't always happen. If light enters a medium at a perpendicular angle, it won't change direction, so its wavelength remains constant.
In Summary
* Refraction: Change in direction due to changing speed.
* Speed: Always slows down in a medium.
* Wavelength: Changes to compensate for the speed change, but only if the light enters the medium at an angle.
Examples:
* Light bending as it enters water from air.
* Light slowing down in a prism, causing different colors to separate (dispersion).
* Microwaves being slowed down in the atmosphere, affecting their communication range.
Let me know if you have any further questions!
