Okay guys, I need you to help me...I´ve got a physical question, I just hope I can translate it, so anybody does understand what I mean....

Okay I´ll start describing the experiment....A light light beam beams onto a white background, through a glass with a "gratings"....anyway the light gets diffracted over 150 times on one millimeter....The light it white in the 0. "diffraction zone" but at the 1. and 2. a spectrum (the colours) appears.....

so the question is, why do colours appear if you diffract light?

Please if you know the answere, try to explain it as easy as you can

I hope my translation isn´t too bad, I don´t really know all the physical terms, but I did my best

 

*not_secure_link*www.what-is-this.com/images/blogs/7-2008/bright-light-16250.jpg

 

yeah thank you that doesn´t help me :lol:

 

My very very simple answer to you is that the "diffraction" you're talking about causes the different wavelengths of light to break up and scatter, thus casting different colored beams of light (at the different wavelengths).

This answer would in no way satisfy anybody with any background in science, so I hope some of the more research-inclined members come around soon.

But that's your basic answer.

 

so its like that the diffraction causes the different wavelengths to break up and so the different colours appear?

 

Different colours are on different wavelengths of light, so when put through glass, the light is scattered in different directions, and because of the angle of refraction and the angle of incidence, the light refracted comes out of the glass at right angles to the way it was shone through the glass. Because of this, the different wavelengths of light are refracted differently in glass, so a white light shone into the glass is broken up into the colours that make it up,making a rainbow.

i hope that's right :S
its been a while since i've done physics, but i'm pretty sure thats the way it works - or its damn close!

 

*not_secure_link*www.motmplus.com/portal/images/products/Magician.jpg
​

 

yeah thats how it works with refracting it, but is it the same with diffracting it?

 

Oh now I get it, its magic...wow thank you Az

 

Well, firstly, you must understand that the colour white light actually has all the colours of the rainbow in. They all mix togetherto form white light.

All these different colours are lights with different wavelengths.When the light passes through a gap, the different wavelenghts diffract at different rates.

The gap is 1/150mm wide. If one of the colours have a wavelength of 1/150mm, it will difract the most and appear on the outside of your band of coulours, and smaller or larger wavelenthg will not diffract as much.

get me? hope that's ok...

 

honestly.....science sucks......just saying "its done by magic" is SOOO much more romantic!

i'm having a love-hate ralationship with science today....

 

Diffracted light

Diffracted light is a phenomenon exhibited by a light’s wave front when passing the edge of an opaque object (one that does not allow light to pass through it). The light becomes modulated, causing a redistribution of the light’s energy within the wave front. You will see it at the edges of the object’s shadow, in the form of minute dark and light bands. The edges of the shadow have a fuzzy appearance. Think of ripples meeting a rock in a pond. They go around the rock in a new series of ripples that can be seen on the sides of the rock. Light waves behaving in a similar manner are said to be diffracted.

 

Yeah I knew all the white light has all the clours thing....

okay so I have one question left.....exactly in front of the light beam, the light was still white, it only showed the colours at the side (because it had it´s intersection there), even though it was all beamed through the "grating", so why is that?

awwww romantic :lol:

 

Okay I got all that, but what causes the spectrum to appear, why do I see the colours? Is it because of the different wavelenghts of the different colours?

 

yes, i explained that earlier as simple as i could, but i'm crap at making things make sense. lol the wavelenths that are the same size to the gap diffract the most, so soem colours are more spread out then others, red is the most diffractiing...i think...

 

Probably red and blue......thank you, I think I got it, I guess my teacher will be okay, if I only give "food for thoughts"......he kinda surprised me today and said, okay you´ll explain tomorrow, and I was like what the hell :lol: but I think I got it, partly, if anybody still cares to explain, I won´t complain

 

[SIZE=+1]How light behaves[/SIZE]

​

Light, whatever its source, moves out in straight lines and spreads out over a larger and larger area as it travels, much the same as ripples in a pond after throwing in a rock. When light strikes an object, it is either absorbed or scattered. Some frequencies are absorbed more than others. This is what gives objects their colors. White surfaces scatter all colors equally, while black surfaces absorb all light.

Editor note: For information on the properties of light and how to control it please go here.
WAYS IN WHICH LIGHT BEHAVES

Light can be:
reflected,
scattered,
transmitted,
diffused,
refracted,
diffracted,
polarized or absorbed

*Reflected light

Light travels in a straight line until it meets an object that alters its course. When it strikes a smooth flat surface, such as a mirror or the calm surface of water, it bounces like a ball off of it at the same angle with which it struck the surface. The reflected light waves remain in the same order as they were when they approached the surface. This is why objects we see in a mirror remain clearly defined.

All objects reflect light. In fact, it is this reflected light that we see and photograph (unless the object produces its own light), not the object itself.
There are three types of reflected light. It can be:
(1) diffuse, reflecting with uniform brightness regardless of the observer’s position,
(2) direct (also known as “specular”), reflecting off a mirror-like surface and visible only by an observer who is directly in the path of the reflection, and
(3) glare, which is also a direct reflection, but is polarized.

Most surfaces will reflect light in all three ways to varying degrees.

*Scattered light

When the surface that is struck by light is rough, the light waves reflect off it at different angles, scattering widely in all directions. Once it is scattered, the light becomes diffused in character.

*Transmitted light

There are two kinds of light transmission - direct and diffused.

We all know that light travels through clear plate glass and other transparent materials, and comes out the other side pretty much unchanged. This light is “transmitted” through the glass, and this type of light transmission - where the light passes through without changing - is known as direct transmission. Direct transmission occurs only when light strikes the surface of the glass head on, that is, at a perpendicular angle. The light will refract if it strikes the glass at any other angle.

*Diffused light

Light will also pass through translucent materials - i.e. materials that permit light to pass through but that also diffuse it so that persons or objects on the other side are not clearly visible or not visible at all. Frosted glass and onion skin paper are examples of translucent materials. Photo studios commonly use translucent material between the studio lights and the subject being photographed to diffuse the light.

The largest example we have of diffused light is the sky itself. Its diffused light is caused by light striking and becoming scattered by molecules of air, dust and water in the atmosphere. Shorter wavelengths are affected more than longer ones. Since the wavelengths of blue light are not as long as those of the reds and yellows, blue light gets more scattered, causing the characteristic blue color of the sky.


*Refracted light

Refraction is a change of direction of a ray of light. Light bends when it strikes light-transmitting substances at any angle other than perpendicular. The density of the transmitting substance - for instance, glass or water - causes a change in the speed of the light, making it alter course to travel through the substance. It picks up its speed again as it leaves the substance, and therefore bends or refracts one more time.

*Diffracted light

Diffracted light is a phenomenon exhibited by a light’s wave front when passing the edge of an opaque object (one that does not allow light to pass through it). The light becomes modulated, causing a redistribution of the light’s energy within the wave front. You will see it at the edges of the object’s shadow, in the form of minute dark and light bands. The edges of the shadow have a fuzzy appearance. Think of ripples meeting a rock in a pond. They go around the rock in a new series of ripples that can be seen on the sides of the rock. Light waves behaving in a similar manner are said to be diffracted.

*Polarized light

Light waves from the sun undulate at all angles, which means that sunlight is not polarized. A polarizing filter can polarize sunlight, making its waves undulate at one angle. When properly used, this filter almost totally eliminates glare and reflections from glass.

*Absorbed light

When light is neither reflected, dispersed nor transmitted by an object, it is absorbed by it.

All materials actually absorb some light in varying amounts. If they didn’t, we would not see things in color. A leaf, for instance, is green because it absorbs red and blue wavelengths and reflects green. Technically-speaking, the colors of most objects are not their true colors. They are instead the colors of light wavelengths that they reflect. Place these objects under a different type of light, and their colors may appear to change, dependent upon how much of that light they absorb and reflect.

Absorbed light disappears as visible light, but its energy continues to exist, having been transformed by absorption, usually into heat. A black shirt absorbs sunlight, and the heat created can be felt by the person wearing the shirt more so than a person wearing a white shirt, which reflects all light.

 

We only see the combined wavelengths as white, it is not, it is multi colored. Refraction or diffraction seperated the wavelengths to ALLOW us to see the different colors.

 

yep. it's the visible spectrum effect

*not_secure_link*www.windows.ucar.edu/physical_science/magnetism/images/visible_spectrum_waves_big.jpg

 

Jamie darlin, if you need to know how light acts in whater, then i'm your gal...marine stuff is no problem, but physics is just beyond me

haha, funny you should post that pic of the ligh spectrum Inky - i used the same one in a presentation on bioluminesence a few months ago