AP Physics 2 / Unit 13: Geometric Optics
13.3 Refraction
Notes
Snell's law: $n_1\sin\theta_1=n_2\sin\theta_2$, with $\displaystyle n=\frac{c}{v}$.
- Light bends toward the normal entering a slower (higher-$n$) medium.
- Total internal reflection happens going to lower $n$ beyond the critical angle: $\displaystyle \sin\theta_c=\frac{n_2}{n_1}$.
Practice
Light goes from air into glass. It bends:
Slower in glass.
Light's speed in a material with $n=1.5$:
$\displaystyle \frac{3\times10^8}{1.5}$.
Total internal reflection can happen when light travels:
High $n$ to low $n$.
Ready for more? Take the Unit 13 test.