Answer:
d = .9 x 10⁻⁶ m
Explanation:
The central bright fringe flanked by bordering two dark fringe will cover the whole of square screen.
Width of central fringe =[tex]\frac{2\lambda D}{d}[/tex]
Where λ is wave length of light , D is distance of screen , d is slit width
putting the values we get
[tex]\frac{2\times 450\times 10^{-9}}{d}=1\\
d=0.9\mu m[/tex]
