NEET2015PhysicsRay OpticsActual
Assertion: A secondary rainbow have inverted colours than the primary rainbow. Reason : The secondary rainbow is formed by single total internal reflection.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion.
- BIfboth assertion and reason are true but reason is not the correct explanation of assertion.
- CIf assertion is true but reason is false.
- DIf both assertion and reason are false.
Correct answer
C. If assertion is true but reason is false.
Step-by-step solution
In the formation of secondary rainbow, light suffers two total internal reflections instead of one. In this, ray undergoes two internal partial reflections having a maximum deviation of about 50^ for red and 54^ for violet. Also secondary rainbow will sometimes be formed with inverted colours. Secondary rainbow is fainter than the primary for two reason (i) the light has undergone two internal reflections and has therebybecomes weakened, (ii) there is greater angular dispersion in this rainbow than in the primary.