The Total solution for NCERT class 6-12
A parallel beam of light ofwavelength 500 nm falls on a narrow slit and the resulting diffraction patternis observed on a screen 1 m away. It is observed that the first minimum is at adistance of 2.5 mm from the centre of the screen. Find the width of the slit.
Wavelength of light beam, λ = 500 nm = 500 × 10−9 m
Distanceof the screen from the slit, D =1 m
For firstminima, n = 1
Distancebetween the slits = d
Distanceof the first minimum from the centre of the screen can be obtained as:
x = 2.5 mm = 2.5 × 10−3 m
It isrelated to the order of minima as:
Therefore, the width of the slitsis 0.2 mm.