Figure below shows a lens of refractive index, $$\mu=1.4$$. $$C_1$$ and $$C_2$$ are the centres of curvature of the two faces of the lens of radii of curvature $$4 \mathrm{~cm}$$ and $$8 \mathrm{~cm}$$ respectively.

The lens behaves as a

When a biconvex lens of glass of refractive index 1.5 is dipped in a liquid, it acts like a plane sheet of paper. This means the refractive index of the liquid is

A hollow prism is filled with water and placed in air. It will deviate the incident rays

In the normal adjustment of an astronomical telescope, the objective and eyepiece are $$32 \mathrm{~cm}$$ apart. If the magnifying power of the telescope is 7, find the focal lengths of the objective and eyepiece.