Question

In the diagram given a ray of light incident on a glass prism. Calculate the refractive index of the glass prism.

Answer 1

Angle of incidence, $\theta =90-i$ angle is measured from normal to the surface prism.

Angle of refraction $r=90-(i+20)=70-i$

Now using the Snell's law,

$n_{air}sin\theta =n_{glass}\times sinr$

so $sin(90-i)=n_{glass}sin(70-i)$

$n_{glass}=\frac{cosi}{sin(70-i)}$