Answer to Question #164560 in Optics for Sama

Question

   A narrow parallel pencil of monochromatic light is incident on a plane boundary between air and

glass. Describe the phenomena which occur as the angle of incidence of the light is progressively

increased from 0° to 90°, (a.) in the air, (b.) in the glass.                    

Answer 1

Answer

The schematic diagram can be shown as

According to concepts of optics

The maximum possible angle of refraction is 90°.if the angle of refraction were greater than 90°, then the refracted ray would lie on the incident side of the medium ,which is not possible. So in the case of the laser beam in the water, there is some specific value for the angle of incidence that yields an angle of refraction of 90$^°$ This particular value for the angle of incidence could be calculated using 

Snell's Law

$\frac{\sin i}{sin r}=\mu$

Where I indicates angle incident or r indicates for refraction.

 (n_i = 1.33, n_r = 1.000,  = 90 °,  ) and would be found to be 48.6°.Any angle of incidence that is greater than 48.6° would not result in refraction. Instead, when the angles of incidence is greater than 48.6 degrees (the critical angle), all of the energy (the total energy) carried by the in process of refraction.