Write the lens maker's equation for a thin lens.

(N/A) The lens maker's equation relates the focal length $(f)$ of a lens to the refractive index of the lens material $(n_2)$,the refractive index of the surrounding medium $(n_1)$,and the radii of curvature of the two lens surfaces ($R_1$ and $R_2$).
The formula is given by:
$\frac{1}{f} = \left( \frac{n_2}{n_1} - 1 \right) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)$
Where:
- $f$ is the focal length of the lens.
- $n_2$ is the refractive index of the lens material.
- $n_1$ is the refractive index of the surrounding medium.
- $R_1$ and $R_2$ are the radii of curvature of the two surfaces of the lens.