Optics Question 1094
Question: In double slit experiment, the angular width of the fringes is 0.20o for the sodium light (l = $ 5890{AA} $ ). In order to increase the angular width of the fringes by 10%, the necessary change in the wavelength is
[MP PMT 1997]
Options:
A) Increase of $ 589{AA} $
B) Decrease of $ 589{AA} $
C) Increase of $ 6479{AA} $
D) Zero
Show Answer
Answer:
Correct Answer: A
Solution:
$ \theta =\frac{\lambda }{d};\theta $ can be increased by increasing l, so here l has to be increased by 10% i.e., % Increase $ =\frac{10}{100}\times 5890=589{AA} $
