<em>Important thing is that all unitless quantity is dimensionless quantity. .</em><em>A</em><em> dimensionless physical quantity may have an unit</em>
A) 1.55
The speed of light in a medium is given by:
where
is the speed of light in a vacuum
n is the refractive index of the material
In this problem, the speed of light in quartz is
So we can re-arrange the previous formula to find n, the index of refraction of quartz:
B) 550.3 nm
The relationship between the wavelength of the light in air and in quartz is
where
is the wavelenght in quartz
is the wavelength in air
n is the refractive index
For the light in this problem, we have
Therefore, we can re-arrange the equation to find , the wavelength in air:
As light from a star races through our atmosphere, it bounces and bumps through the different layers, bending the light before you see it. Since the hot and cold layers of air keep moving, the bending of the light changes too, which causes the star's appearance to wobble or twinkle.
You may look at what group they are in
Group
1A=Group 1
2A = Group 2
3A = Group 13
4A= Group 14
5A=Group 15
6A=Group 16
7A=Group 17
The #A tells you how many valence electrons there are by the # before A. Such as Chlorine, which is in 7A, so therefore has 7 valence electrons.
Longitude was. Determining longitude requires knowing the exact time of day, which was difficult prior to modern clocks. The source book below tells the story of Englishman John Harrison's life-long pursuit of building a reliable clock and its importance to navigation.
