Optics Question 198

Question: A slit of size 0.15 cm is placed at 2.1 m from a screen. On illuminated it by a light of wavelength 5 x 10^-5 cm. The width of central maxima will be

[RPMT 1999]

Options:

A) 70 mm

B) 0.14 mm

C) 1.4 mm

D) 0.14 cm

Show Answer

Answer:

Correct Answer: C

Solution:

Width of central maxima $ =\frac{2\lambda D}{d} $

$ =\frac{2\times 2.1\times 5\times {{10}^{-7}}}{0.15\times {{10}^{-2}}}=1.4\times {{10}^{-3}}m=1.4\ mm $



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