1. A ray of light travels from water to glass. What will be the angle of refraction in glass if the angel of incidence in water is 20 degree? The refractive index of water is 1.33 and that of glass is 1.5.
  2. A ray of light falls on a transparent glass of refractive index 1.62. If the reflected ray and refracted ray are mutually perpendicular, what is the angle of incidence?

Asked by Sukrit Saha | 10th Dec, 2015, 08:24: PM

Expert Answer:

2. 
Let the incident ray MO fall on a transparent glass slab at the point of incidence O. 
From the figure, OP and OR are reflected and refracted rays. The reflected and refracted rays are mutually perpendicular.
Therefore, begin mathsize 14px style angle POR equals 90 degree end style
begin mathsize 14px style angle N O P plus angle POR plus angle R O N apostrophe equals 180 degree end style
i + 90º + r = 180º
i + r = 90º
or r = 90º - i
From Snell's law,
begin mathsize 14px style straight mu equals fraction numerator sin space straight i over denominator sin space straight r end fraction space space space equals fraction numerator sin space straight i over denominator sin space left parenthesis 90 degree minus straight i right parenthesis end fraction space space space equals fraction numerator sin space straight i over denominator cos space straight i end fraction space space space equals space tan space straight i Angle space of space incidence comma space straight i equals tan to the power of negative 1 end exponent left parenthesis straight mu right parenthesis space equals tan to the power of negative 1 end exponent left parenthesis 1.62 right parenthesis therefore straight i equals 58 degree 19 apostrophe end style
 
 
Note: Kindly ask the other question as a separate query.

Answered by Faiza Lambe | 11th Dec, 2015, 08:14: AM