question_answer

A ray of light falls on the surface of a spherical glass paper weight making an angle \[\alpha \] with the normal and is refracted in the medium at an angle \[\beta \]. The angle of deviation of the emergent ray from the direction of the incident ray [NCERT 1982]

A)            \[(\alpha -\beta )\]           

B)            \[2(\alpha -\beta )\]

C)            \[(\alpha -\beta )/2\]       

D)            \[(\beta -\alpha )\]

Correct Answer: B

Solution :

                   From the following ray diagram it is clear that                    \[\delta =(\alpha -\beta )+(\alpha -\beta )\]\[=2(\alpha -\beta )\]