Answer:
80 cm
Explanation:
To find the minimum distance from the slits to the screen you use the following formula for the m-th fringe of the interference pattern:
[tex]y=\frac{m\lambda D}{d}[/tex]
m: order of the fringe
λ: wavelength = 632.8*10^-9 m
D: distance to the screen
d: distance between slits = 0.034*10^-3
for the distance between fringes you have:
[tex]\Delta y=y_{m+1}-y_m=\frac{\lambda D}{d}=1.5cm=1.5*10^{-2}\ m[/tex] ( 1 )
By replacing the values of the parameters in (1) you can find the distance D to the screen:
[tex]D=\frac{\Delta y d}{\lambda}=\frac{(1.5*10^{-2}m)(0.034*10^{-3}m)}{632.8*10^{-9}m}=0.80m=80\ cm[/tex]
hence, the distance from the slits to the screen is 80 cm
