Question

A ray of light is minimally deviated when incident at an angle 30 degrees on one face of a glass prism of refractive index 1.5. The minimum angle of deviation is?

Answer 1

Solution;

$n = \frac{sin i}{sin r}$

$sin r = \frac{30^o}{n}$

$sin r = \frac{0.5}{1.5}$

Then, $sin r = 0.3333$

solving you find $r=19.5\degree$

Therefore deviation is; $30\degree-19.5=10.5\degree$