Embibe Experts Solutions for Chapter: Ray Optics and Optical Instruments, Exercise 1: Uttar Pradesh Board-2019

Define first focus of a concave lens.

Draw a ray diagram of astronomical telescope and derive the formula of its magnifying power, when final image is formed at the least distance of the distinct vision.

A ray of light incident on face $\mathrm{AB}$ of an equilateral glass prism, shows minimum deviation angle of ${30}^{\mathrm{o}}$. Calculate the speed of light through the prism. Find the angle of incidence at the face $\mathrm{AB}$ so that the emergent ray grazes along the face $\mathrm{AC}$.

Given: Speed of light in vacuum

$=3\times {10}^8 {\mathrm{ms}}^{-1} \mathrm{and} \sin {15}^{\mathrm{o}}=\frac{\sqrt{3}-1}{2\sqrt{2}}$

When a ray of light enters in a medium of refractive index $\mathrm{n}$, the angle of refraction is half of the angle of incidence. Value of the angle of refraction will be

An object is kept in front of a concave mirror of $15 \mathrm{cm}$ focal length. The image formed is real and three times the size of the object. Find the distance of the object from the mirror.

Draw a labelled ray diagram of an astronomical telescope, when final image is formed at the least distance of the distinct vision. Which of the following convex lenses are to be used for making a telescope having maximum magnifying power ? 

Derive the formula for the refraction at a convex spherical surface.

Derive the formula for the focal length of a thin lens with the help of refraction formula of spherical surface.