Answer to Question #214919 in Optics for lala

Question

Several monochromatic lights pass through double slits with a separation of s 50 3m. The screen to slits distance is 2.5 m. What is/are the width of its central maximum and its corresponding wavelength(s) where the bright spot can occur? [width is expressed in 3 significant figures]

Wavelength (nm) Width (cm)

A. 350 1.75

B. 400 2.00

C. 575 5.75

D. 700 3.50

Answer 1

Gives

$d=503nm \\D=2.5m\\\theta=53°$

Central bright fringe

$m\lambda=dsin\theta$

Put value

m=1

$\lambda=503\times sin53°$

$\lambda=400.17$ nm

$\lambda=400nm$

Fring width

$\beta=\frac{\lambda D}{d}=\frac{400\times10^{-9}\times2.5}{503\times10^{-9}}=2.0$

Option (b) is correct option