Why is Class 12 Physics Chapter 9 Ray Optics important for CBSE Board and competitive exams?

Rainbow is formed due to internal reflection and dispersion.

In hypermetropia image formed by eye lens is beyond retina and is focussed to retina by a convex lens.

Heat is path dependent so path function but internal energy does not depend on path chosen.

f = 15

$m=-\frac{v}{u}=+\frac{1}{2}$            

  $v=-\frac{u}{2}$           

$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$            

$\frac{2}{-u}+\frac{1}{u}=\frac{1}{f}$            

u = – f = – 15cm

$\frac{1}{20}=\left(1.5-1\right)\left(\frac{2}{R}\right)$

R = 20cm

$\frac{1}{f\text{'}}=\left(\frac{1.5}{1.6}-1\right)\left(\frac{2}{R}\right)$            

$=\frac{-1}{16}\times \frac{2}{20}$                  

f' = – 160cm