Answer:

Explanation:
The expression which represent the first diffraction minima by a circular aperture is given by
--------eqn 1
The angle through which the first minima is diffracted is given by
---------eqn 2
As
is very small so we can write 
So from eqn 1 and eqn 2 we can write
--------eqn 3
Here
is the position of first maxima D is the distance of screen from the circular aperture d is the diameter of aperture
It is given that diameter of circular aperture is 14.7 cm so 
Now putting all these value in eqn 3


Answer:
3.82 Hertz
Explanation:

This is the equation of a wave which varies sinusoidally.
The standard equation of a wave is given by

where, A be the amplitude of the wave, k be the wave number, x be the displacement of wave, ω be the angular frequency and t be the time taken, and Ф be the phase angle.
now compare the given equation by the standard equation, we get
k = 3
ω = 24
Ф = π / 2
So, the angular frequency = 24
The relation between the angular frequency and the frequency is given by
ω = 2 x π x f
24 = 2 x 3.14 x f
f = 3.82 Hertz
concentration is the ratio of solute in a solution to either solvent or total solution.
I have no idea just getting points