Explanation:
It is given that,
The distance between the first spot and the central minimum is, s = 0.007 cm
Length, l = 12 m
Wavelength, [tex]\lambda=6\times 10^{-7}\ m[/tex]
We need to find the width of the hair. Using the condition of diffraction pattern as :
[tex]s=\dfrac{m\lambda l}{d}[/tex], d is the width of the hair
[tex]d=\dfrac{m\lambda l}{s}[/tex]
[tex]d=\dfrac{1\times 6\times 10^{-7}\times 12}{0.007}[/tex]
d = 0.00102
or
[tex]d=1.02\times 10^{-3}\ m[/tex]
So, the width of the hair is [tex]1.02\times 10^{-3}\ m[/tex]. Hence, this is the required solution.