A parallel beam of light of 500 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen 1 m away. It is observed that the first minimum is at a distance of 2.5 mm from the centre of the screen. Calculate the width of the slit. (2)



The distance of the nth minimum from the center of the screen is,Where, D = distance of slit from screen, λ = wavelength of the light, a = width of the slitFor first minimum, n=1Thus,