question_answer

A prism having an apex angle \[4{}^\circ \] and refractive index 1.5 is located in front of a vertical plane mirror as shown in figure. Through what total angle is the ray deviated after reflection from the mirror?

A) \[176{}^\circ \]            

B) \[4{}^\circ \]

C) \[178{}^\circ \]            

D) \[2{}^\circ \]

Correct Answer: C

Solution :

\[\delta =(\mu -1)\,A=\left( 1.5-1 \right)\,4=2{}^\circ \] \[Deviation\text{ }by\text{ }mirror=180-\angle i=176{}^\circ \] \[\therefore \,\,\text{ }Total\text{ }deviation=2+176=178{}^\circ \]