A beam of light of = 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between first dark fringes on either side of the central bright fringe is
- 1.2 cm
- 1.2 mm
- 2.4 cm
- 2.4 mm
Answer
(4) 2.4 mm
Solution
Distance between the first minima on either side = width of the central maximum:
0 = 2 Da
= 2 600 10-9 21 10-3
= 2.4 10-3 m = 2.4 mm
Answer: (4)