Answer:
a
The angle between the center and the third side bright fringe is
b
The third side bright fringe move away from the pattern's center
c
The distance by which it moves away is

Step-by-step explanation:
From the question the
The wavelength is

In the first question we a asked to obtain the angle between the center and the third side bright fringe
since we are considering the third side of the bright fringe the wavelength of light on the three sides would be evaluated as
The slit separation is given as

The angle between the center and the third side bright fringe is



When the frequency of the light is reduced the wavelength is increased
i.e
and this increase would cause the third side bright to move away from the pattern's center
Now from the question frequency is reduce to 94.5% this mean that the wavelength would also increase by the same as mathematically represented below


The angle between the center and the third side bright fringe is for new wavelength


The distance traveled away from the pattern's center is mathematically represented as

Where A is the separation between the slits and the screen

