Answer:
Explanation:
a ) Distance of screen (D) = 50 X 10⁻²
Wavelength of light λ = 690 x 10⁻⁹
d = width of slit
Distance between first and third dark fringe = 2 x fringe width
= 2 x λD/d = 3 x 10⁻³
d = 2 x 690 x 10⁻⁹ x 50 x 10⁻² /3 x 10⁻³ = 0.23 mm
b ) Width of central bright fringe = 2 λD/d
2 x 690 x 10⁻⁹ x 50 x 10⁻² /23 x 10⁻⁵ m
= 3 mm.
