Question

In young's double slit experiment, distance between two slits is 0.28 mm and distance between slits and screen is 1.4 m. Distance between central bright fringe and third bright fringe is 0.9 cm. What is the wavelength of light used?

Answer 1

Answer:

450

Explanation:

Distance between the slits, d = 0.28 mm = 0.28 × 10−3 m

Distance between the slits and the screen, D = 1.4 m

Distance between the central fringe and the fourth (n = 4) fringe,  

u = 0.9 cm = 0.9 × 10−2 m

In case of a constructive interference, we have the relation for the distance between the two fringes as -

u = nλD/d, where n = order of fringes and 4λ = wavelength of light

Thus,

= 0.9 × 10−2 × 0.28×10-3/4×1.4

= 4.5×10-7

= 450

Hence, the wavelength of the light is 450 nm