Question

  A ray of light is incident in air at an angle of 40° to the normal to one face of a 60° glass prism.

   Calculate the angle through which the ray has been deviated by the time it emerges from the prism.

Answer 1

Angle of prism $A=60^{\circ}$

Angle of incidence $i_1=40^{\circ}$

Let angle of deviation be $\delta$

As we know $r_1=r_2=\dfrac{A}{2}=30^{\circ}$

Using snell's law-

 Refractive index $\mu=\dfrac{sin i_1}{sin r_1}=\dfrac{sin 40}{sin30}=1.2855$

Angle of deviation is given by-

$\delta=(\mu-1)A$

$=(1.2855-1)\times 60\\=0.2855\times 60=17.13^{\circ}$