Monochromatic light of wavelength produces an interference pattern on a screen away…

PHYSICS · Subjective · A Level · Physics · Waves · Waves

Problem

Monochromatic light of wavelength

500\,\text{nm}

produces an interference pattern on a screen

1.2\,\text{m}

away from two slits separated by

0.40\,\text{mm}

. How many complete dark fringes lie between the points located

2.0\,\text{mm}

and

7.0\,\text{mm}

above the central maximum on the screen?