Optics Question 1077
Question: The Young’s experiment is performed with the lights of blue (l = 4360 Å) and green colour (l = 5460 Å), If the distance of the 4th fringe from the centre is x, then
[CPMT 1987]
Options:
A) x (Blue) = x (Green)
B) x (Blue)> x (Green)
C) x (Blue) < x (Green)
D) $ \frac{x(Blue)}{x(Green)}=\frac{5460}{4360} $
Show Answer
Answer:
Correct Answer: C
Solution:
Distance of nth bright fringe $ y _{n}=\frac{n\lambda D}{d}i.e.\ y _{n}\propto \lambda $
$ \therefore \frac{{x _{n _{1}}}}{{x _{n _{2}}}}=\frac{{\lambda _{1}}}{{\lambda _{2}}}\Rightarrow \frac{x(Blue)}{x(Green)}=\frac{4360}{5460} $
$ \therefore $ x (Green) > x (Blue).
