A point object at $15 \mathrm{cm}$ from a concave mirror of radius of curvature $20 \mathrm{cm}$ is made to oscillate along the principal axis with amplitude $2 \mathrm{mm}$. The amplitude of its image will be 

The distance between an object and its doubly magnified image by a concave mirror is 

[Assume $f=$ focal length]

An observer $\text{'}O\text{'}$ sees the distance $\mathrm{AB}$ as infinitely large. If the refractive index of the liquid is ${\mu }_1$ and that of glass is ${\mu }_2$ then $\frac{{\mu }_1}{{\mu }_2}$ is

In the given figure a plano-concave lens is placed on a paper on which a flower is drawn. How far from its actual position does the flower appear to be?