question_answer

A single slit of width 0.1 mm is illuminated by a parallel beam of light of wavelength \[6000\overset{\text{o}}{\mathop{\text{A}}}\,\] and diffraction bands are observed on a screen 0.5 m from the slit. The distance of the third dark band from the central bright band is –                              [JEE Online 09-04-2017]

A) 9 mm

B) 3 mm

C) 4.5 mm

D) 1.5 mm

Correct Answer: A

Solution :

[a]

for 3rd dark