Question

what is the formula for double convex lens

Answer 1

$$\begin{gathered} \mathbf{Lens}\mathbf{}\mathbf{maker}\mathbf{\text{'}}\mathbf{s}\mathbf{}\mathbf{formula}\mathbf{}\mathbf{for}\mathbf{}\mathbf{double}\mathbf{}\mathbf{convex}\mathbf{}\mathbf{lens}\mathbf{:} \\ \frac{\mathbf{1}}{\mathbf{f}}\mathbf{=}\left(\mathbf{\mu }\mathbf{-}\mathbf{1}\right)\left(\frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{1}}}\mathbf{+}\frac{\mathbf{1}}{{\mathbf{R}}_{\mathbf{2}}}\right) \\ \mathbf{Here}\mathbf{,} \\ \mathbf{f}\mathbf{}\mathbf{is}\mathbf{}\mathbf{focal}\mathbf{}\mathbf{length}\mathbf{,} \\ \mathbf{\mu }\mathbf{}\mathbf{is}\mathbf{}\mathbf{refractive}\mathbf{}\mathbf{index}\mathbf{,} \\ {\mathbf{R}}_{\mathbf{1}}\mathbf{}\mathbf{is}\mathbf{}\mathbf{Radius}\mathbf{}\mathbf{of}\mathbf{}\mathbf{curvature}\mathbf{}\mathbf{of}\mathbf{}\mathbf{first}\mathbf{}\mathbf{refracting}\mathbf{}\mathbf{surface} \\ {\mathbf{R}}_{\mathbf{2}}\mathbf{}\mathbf{is}\mathbf{}\mathbf{Radius}\mathbf{}\mathbf{of}\mathbf{}\mathbf{curvature}\mathbf{}\mathbf{of}\mathbf{}\mathbf{second}\mathbf{}\mathbf{refracting}\mathbf{}\mathbf{surface} \end{gathered}$$