Answer:
The pattern would spread out.
Explanation:
The fringe width is given by the relation
fringe width = λ L / D where λ is wavelength of light used, L is distance of wall from the source of light and D is slit separation.
If we increase λ , fringe width will increase and therefore pattern will spread out .
Answer:
The speed of the galaxy relative to the Earth is 
.
Explanation:
We have,
(a) Wavelength emitted by light at distant galaxy is 434.1 nm. On earth, the wavelength of this light is measured to be 438.6 nm. It can be seen that the wavelength of light reduces as it reaches Earth. It is called Red shift. As per Doppler's effect, we can say that the galaxy is receding from the Earth.
(b) Let v is the speed of the galaxy relative to the Earth. It can be given by :
So, the speed of the galaxy relative to the Earth is .
Remark
All the statements are correct except for B
B is wrong because the Force is inversely proportional to the square of the distance.
D is correct. That's what Newton saw when he watched the apple fall. The apple did all the moving.
A is correct. The formula is
F = G*m1*m2/r^2
If r is held constant the formula becomes
F = k * m1 * m2 where k = G/r^2
C is true as well, but it sure decreases in strength because of the distance and the smallness of G.
Answer: 
Explanation:
The mean free path 
of an atom is given by the following formula:
(1)
Where:
is the Universal gas constant
is the absolute standard temperature
is the diameter of the helium atom
is the Avogadro's number
absolute standard pressure
Knowing this, let's find from (1), in order to find the radius 
of the helium atom:
(2)
(3)
(4)
If the radius is half the diameter:
(5)
Then:
(6)
(7)
However, we were asked to find this radius in nanometers. Knowing 
:
(8)
Finally:
This is the radius of the helium atom in nanometers.
