Ray Optics and Optical Instruments

9.1 Refraction at a Spherical Surface

When light refracts at a spherical surface separating two media of refractive indices $n_1$ and $n_2$:

$$\frac{n_2}{v} - \frac{n_1}{u} = \frac{n_2 - n_1}{R}$$

where $R$ is the radius of curvature of the surface.