A ray of light is incident in situation as shown in figure.

Which of the following statements `is//are` true?

Options

A. If `mu_(2) = 3.2` then the angle of deviation is zero
B. If `mu_(2) = 2.8` then the angle of deviation is `60^(@)`
C. If `mu_(2) = 1.8` then the angle of deviation is `120^(@)`
D. If `mu_(2) = 1.8` then the angle of deviation is `60^(@)`

Answer

B, C

Explanation

`mu_(1) "sin" 30^(@) = mu_(2)"sin"theta= mu_(3)"sin"theta_(1) implies 2= mu_(2)"sin"theta = 2 "sin"theta_(1) implies theta_(1) = 90^(@) "and" mu_(2) gt 2`
For `mu_(2) lt 2 , TIR` will take place at first surface.

`implies delta = 120^(@)`