* Refraction: Refraction is the bending of a wave as it passes from one medium to another. This happens because the wave's speed changes as it enters the new medium.
* Speed and Wavelength: The speed of a wave is related to its frequency (how many wave crests pass a point per second) and its wavelength (the distance between two crests). The relationship is:
* Speed = Frequency x Wavelength
* Frequency is Constant: When a wave refracts, its frequency usually remains the same. This is because the source of the wave (e.g., the light source) continues to emit waves at the same rate.
* Speed Changes, Wavelength Adjusts: Since frequency stays the same, and the speed changes during refraction, the wavelength *must* change to maintain the relationship between speed, frequency, and wavelength.
How the wavelength changes:
* Slower medium: If the wave travels into a medium where it slows down, the wavelength will decrease.
* Faster medium: If the wave travels into a medium where it speeds up, the wavelength will increase.
Example:
Light traveling from air into water slows down. To maintain the constant frequency, the wavelength of the light will decrease in the water. This is why a straw in a glass of water appears to be bent at the water's surface.
