Optics Question 37
Question: Assertion : Dispersion of light occurs because velocity of light in a material depends upon its colour. Reason : The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism.
Options:
A) If both assertion and reason are true and the reason is the correct explanation of the assertion.
B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
C) If assertion is true but reason is false.
D) If the assertion and reason both are false.
E) If assertion is false but reason is true.
Show Answer
Answer:
Correct Answer: B
Solution:
The velocity of light in a material medium depends upon it’s colour (wavelength).
If a ray of white light incident on a prism, then on emerging, the different colours are deviated through different angles.
Also dispersive power $ \omega =\frac{({\mu _{V}}-{\mu _{R}})}{({\mu _{Y}}-1)} $ i.e. w depends upon only m.
