The key idea
When light crosses between media, its propagation speed changes and its direction generally changes as described by Snell’s law.
Why it matters
Frequency remains fixed across a stationary boundary while wavelength changes with propagation speed.
A picture to remember
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
The key idea
When light crosses between media, its propagation speed changes and its direction generally changes as described by Snell’s law.
Refraction of lightn₁sinθ₁ = n₂sinθ₂
The key idea
Frequency remains fixed across a stationary boundary while wavelength changes with propagation speed.
Frequency remains fixed across a stationary boundary while wavelength changes with propagation speed.