A classic observation of refraction occurs when a pencil is placed in a glass half filled with water. Do this and observe the shape of the pencil when you look at the pencil sideways, that is, through air, glass, water. Explain your observations. Draw ray diagrams for the situation.
Determine the index of refraction from refraction data
Find the index of refraction for medium 2 in
[link] (a), assuming medium 1 is air and given the incident angle is
and the angle of refraction is
.
Strategy
The index of refraction for air is taken to be 1 in most cases (and up to four significant figures, it is 1.000). Thus
here. From the given information,
and
. With this information, the only unknown in Snell’s law is
, so that it can be used to find this unknown.
Solution
Snell’s law is
Rearranging to isolate
gives
Entering known values,
Discussion
This is the index of refraction for water, and Snell could have determined it by measuring the angles and performing this calculation. He would then have found 1.33 to be the appropriate index of refraction for water in all other situations, such as when a ray passes from water to glass. Today we can verify that the index of refraction is related to the speed of light in a medium by measuring that speed directly.
Suppose that in a situation like that in
[link] , light goes from air to diamond and that the incident angle is
. Calculate the angle of refraction
in the diamond.
Strategy
Again the index of refraction for air is taken to be
, and we are given
. We can look up the index of refraction for diamond in
[link] , finding
. The only unknown in Snell’s law is
, which we wish to determine.
Solution
Solving Snell’s law for sin
yields
Entering known values,
The angle is thus
Discussion
For the same
angle of incidence, the angle of refraction in diamond is significantly smaller than in water (
rather than
—see the preceding example). This means there is a larger change in direction in diamond. The cause of a large change in direction is a large change in the index of refraction (or speed). In general, the larger the change in speed, the greater the effect on the direction of the ray.
The changing of a light ray’s direction when it passes through variations in matter is called refraction.
The speed of light in vacuum
Index of refraction
, where
is the speed of light in the material,
is the speed of light in vacuum, and
is the index of refraction.
Snell’s law, the law of refraction, is stated in equation form as
.
Conceptual questions
Diffusion by reflection from a rough surface is described in this chapter. Light can also be diffused by refraction. Describe how this occurs in a specific situation, such as light interacting with crushed ice.
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life