Telangana Board-2020

A small angled prism of $4°$ deviates a ray through $2.48°$. Find the refractive Index of the prism. 

With a neat labelled diagram explain the formation of image in a simple microscope.

What focal length should the reading spectacles have for a person for whom the least distance of vision is $50 \mathrm{cm}$? (The normal distance of vision is $25 \mathrm{cm}$).

Explain the formation of Mirage.

A concave mirror produces an image of a long vertical pin, placed $40 \mathrm{cm}$ from the mirror, at the position of the object. Find the focal length of the mirror (in $\mathrm{cm}$). 
 

Explain the formation of a rainbow.

How do you determine the resolving power of your eye?

What are cathode rays?