JEE Main & Advanced Physics Ray Optics Lens Maker's Formula and Lens Formula

Lens Maker's Formula and Lens Formula

Category : JEE Main & Advanced

(1) Lens maker's formula : If \[{{R}_{1}}\] and \[{{R}_{2}}\] are the radii of curvature of first and second refracting surfaces of a thin lens of focal length f and refractive index \[\mu \] (w.r.t. surrounding medium) then the relation between f, m, \[{{R}_{1}}\] and \[{{R}_{2}}\] is known as lens maker's formula.

\[\frac{1}{f}=(\mu -1)\left( \frac{1}{{{R}_{1}}}-\frac{1}{{{R}_{2}}} \right)\]

Focal length of different lenses

Lens Focal length For  \[\mu =1.5\]

Biconvex lens



\[f=\frac{R}{2(\mu -1)}\] \[f=R\]

Plano-convex lens

\[{{R}_{1}}=\infty \]


\[f=\frac{R}{(\mu -1)}\] \[f=2R\]




\[f=-\frac{R}{2(\mu -1)}\] \[f=-R\]


\[{{R}_{1}}=\infty \]


\[f=\frac{-R}{(\mu -1)}\] \[f=-2R\]

(2) Lens formula : The expression which shows the relation between u, v and f is called lens formula.        


You need to login to perform this action.
You will be redirected in 3 sec spinner