Physics · Grades 9–12
Refraction and critical conditions · Revision sheet
Track speed, wavelength and angle while frequency stays tied to the source.
Learn the idea
Index
Refractive index relates vacuum light speed to speed in a medium: n = c/v.
Frequency
At a stationary boundary the transmitted wave keeps the source frequency while speed and wavelength may change.
Snell's law
n₁ sin θ₁ = n₂ sin θ₂, with angles from the normal.
Total internal reflection
It requires travel from higher to lower refractive index and incidence above the critical angle. Not every boundary crossing can produce it.
Explain without looking
- Why is the phrase light always bends when changing medium too broad?
- Which angle definition belongs in Snell's law?
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.