An equiconvex lens of glass (${\mathrm{\mu }}_{\mathrm{g}}$ =1.5) of focal length 10 cm is silvered on one side. It will behave like a

For equiconvex lens

$\left|{\mathrm{R}}_1\right|=\left|{\mathrm{R}}_2\right|=\mathrm{f}=10\mathrm{cm}$

$\begin{array}{l}\mathrm{if}{\mathrm{\mu }}_{\mathrm{g}}=1.5\\ \mathrm{now}\mathrm{P}=2{\mathrm{P}}_{\mathrm{L}}+{\mathrm{P}}_{\mathrm{M}}\\ \mathrm{or}-\frac{1}{\mathrm{F}}=2\left(\mathrm{\mu }-1\right)\left(\frac{1}{{\mathrm{R}}_1}-\frac{1}{{\mathrm{R}}_2}\right)+\frac{2}{R}=2\left(1.5-1\right)\left(\frac{1}{10}-\frac{1}{-10}\right)-\frac{2}{-10}\\ \mathrm{or}\mathrm{F}=-2.5\mathrm{cm}\\ \mathrm{Theref}o\mathrm{re},\mathrm{the}\mathrm{system}\mathrm{will}\mathrm{behave}\mathrm{like}\mathrm{a}\mathrm{concave}\mathrm{mirror}\end{array}$