Physics
A ray of white light is incident on the interface of glass and air as shown in the figure. At the given angle of incidence, green light suffers total internal reflection. The rays emerging out from glass to air contain :
- yellow, orange and red colours
- violet, indigo and blue colours
- all colours
- all colours except green
Answer
yellow, orange and red colours
Reason — When white light passes from glass to air, different colours have different critical angles. Colours with higher refractive index (violet, indigo, blue) undergo total internal reflection more easily. If green light undergoes total internal reflection, then these colours will also be totally reflected. Only colours with lower refractive index—yellow, orange and red—will emerge from the glass.
Hence, yellow, orange and red colours will emerge out from glass to air.
Related Questions
In the process of total internal reflection, …………… of energy (or intensity) of light is reflected back.
- 70%
- 80%
- 100%
- 50%
Out of violet, blue, yellow and red, the critical angle would be the least for …………… light for a pair of media.
- violet
- blue
- blue
- yellow
How is the critical angle related to the refractive index of a medium?
The critical angle for glass-air is 45° for the light of yellow colour. State whether it will be less than, equal to, or more than 45° for
(i) red light,
(ii) blue light ?