Boundary Behaviour: Reflection, Refraction & Diffraction Explained

[Misr]

Hellllllllllo World
1-
[url]http://www.physicsclassroom.com/Class/refrn/u14l3a1.gif[/url]

When a light ray falls on the boundary between two media , some of the energy is reflected back to the first medium,some energy refracts and some energy is absorbed.
how is this exlplained?does it has something to do with the natural frequency of the electrons?

A light ray is a combination of different wavelengths ( different frequencies),if some frequencies were the same as the natural frequencies of the elctrons of water,they are absorbed and the other wavelengths are refracted and reflected.
Is that true?I mean does this explains the previous?Actually,I don't think so.

but this begs another question:What does the intensity of refraction and reflection depends upon?we study that it depends upon the difference between speed of light in the two median light falls from air to water ,most of the energy is reflected since the difference in speed between the two media is great.How to explain something like this?


2-I have a big misconception about diffraction:I think that in order for difrraction to occur, the wavelength must be smaller than the dimensions of the slit

if the wavelength is larger than the dimensions of the slit,diffraction cannot occur.
I got this misconception from the equation :
http://library.thinkquest.org/19537/media/equation1.gif
see this page
http://library.thinkquest.org/19537/Physics6.html
and since the value of the sine cannot be larger than one , I concluded the previous MISCONCEPTION
and also According to the equation,we can conclude that diffraction is greatest when the wavelength is equal to the dimensions of the slit
okay,
why do I call this a "misconception"?
see this page

If the boundary is merely an obstacle implanted within the medium, and if the dimensions of the obstacle are smaller than the wavelength of the wave, then there will be very noticeable diffraction of the wave around the object

http://www.physicsclassroom.com/Class/refrn/u14l1a.cfm
in addition to that,all the teachers assured the previous quotation that the dimensions of the obstacle are smaller than the wavelength of the wave, then there will be very noticeable diffraction of the wave around the object.

Thanks in Advance.

 

[AndyW]

Hello there,

Thank you for sharing your thoughts and questions about the concepts of reflection, refraction, and diffraction. I can offer some explanations and clarifications to help deepen your understanding.

Firstly, the phenomenon of reflection and refraction can be explained by the wave nature of light. When a light ray strikes the boundary between two media, some of the light is reflected back because the boundary acts as a barrier, not allowing the light to pass through. The amount of reflection depends on the difference in the refractive indices of the two media. The refractive index is a measure of how much light slows down when it enters a medium. If the difference in refractive indices is large, then most of the light will be reflected. This is why, as you mentioned, when light falls from air to water, most of the energy is reflected because the refractive index of water is significantly different from that of air.

Now, for refraction. As you correctly stated, when light passes from one medium to another, it changes speed and direction. This is because the different wavelengths (colors) of light travel at different speeds in different media. This is also related to the natural frequency of electrons, as you mentioned. When light passes through a medium, it interacts with the electrons in that medium. If the natural frequency of the electrons matches the frequency of the light, then the light is absorbed by the electrons, resulting in a decrease in speed. This is why different colors of light bend at different angles when passing through a prism – they have different frequencies and interact with the electrons in the prism differently.

Now, let's move on to diffraction. Your misconception about diffraction is understandable, but it is important to remember that diffraction can occur for any size of the slit, as long as the wavelength of the light is comparable to the size of the slit. The equation you referenced is known as the "diffraction grating equation" and it is used to calculate the angles at which light will diffract when passing through a grating with evenly spaced slits. As the number of slits increases, the diffraction pattern becomes more pronounced. This is why, as you mentioned, diffraction is greatest when the wavelength is equal to the dimensions of the slit. However, this does not mean that diffraction cannot occur for larger or smaller wavelengths. In fact, diffraction is a fundamental property of waves and it occurs whenever a wave encounters an obstacle or