Question

What will be the linear width of the central maximum on a screen that is kept 5 m away from the slit, if a light of wavelength 800 nm strikes a slit of 5 mm width.

(a) 1.2 mm

(b) 5.6 mm

(c) 6.5 mm

(d) 9.7 mm

I got this question in semester exam.

This intriguing question comes from Wave Optics topic in portion Wave Optics of Physics – Class 12

Answer 1

Right choice is (a) 1.2 mm

The explanation is: Linear width is given as:

β0 = \(\frac {2D\lambda }{d}\)

β0 = \( \frac { ( 2 \times 5 \times 800 \times 10^{-9} ) }{ (5 \times 10^{-3} ) }\)

β0 = 1.6 × 10^-3 m

β0 = 1.6 mm

Therefore, the linear width of central maximum on a screen kept 5 m away from the slit is 1.6 mm.