Answer:
(a) Expands
(b) decreases
Solution:
As per the question:
Width of the central maxima for a single slit diffraction can be given as:
[tex]w = \frac{2\lambda d}{x}[/tex]
where
w = width
[tex]\lambda = wavelength[/tex]
x = slit width
Now,
From the above expression, width, w is proportional to the wavelength and slit width is in inverse proportion to the width of the central maxima.
w ∝ [tex]\lambda [/tex]
And
w ∝ [tex]\frac{1}{x}[/tex] (1)
We know that, red light has the longest wavelength whereas blue light has the shortest wavelength:
[tex]\lambda_{red}[/tex] > [tex]\lambda_{red}[/tex]
width of the central maxima is greater for red light than for blue light
(a) Thus on replacing by red light the pattern broaden
(b) From eqn (1):
When the slit width, x is increased the width of the central maxima, w decreases.
