Critical angle (TIR) (sin θc = n2/n1 (rarer over denser))
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sin θc = n2/n1 (rarer over denser)
What each symbol means
| Symbol | What it stands for |
|---|---|
| n_1 | Refractive index of denser medium (incident side, inside medium) |
| n_2 | Refractive index of rarer medium (refracted side, e.g. air) |
| \theta_c | Critical angle measured from the normal (sin θc = n2/n1 when n1 > n2) |
When to use this
Standard JEE / NCERT assumptions unless stated (paraxial, thin lens, coherent YDSE sources, etc.).