Dave's ESL Cafe's Student Discussion Forums

[NMO2]

How does different colored water make the water gain and retain thermal energy at different speeds? Why do darker colors like blue, black, and violet gain and retain thermal energy faster and longer than lighter colors like yellow, orange, and red? Would yellow water gain more thermal energy than plain water? What causes these changes? How come color has this effect and why? Please help me!
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Natalie

[stellara]

okay, that's a bit difficult to explain, especially in english..
white light contains every colour of the optical spectrum. it can be dispersed by a prism into these colours
see:


so if white light falls onto a (for us) red object, the reason why we see it red is that because of its chemical structure (along with some other things) it can absorb every single colour of the optical spectrum except red. so we see it red. (same goes with evey other colour we see!)

light is energy (E = mc2, if you know), so naturally if an object absorbs light, it absorbs energy and heats.
so, we know that white contains every colour, and black contains none. so the darker an object is, the more light it can absorb, the more (thermal) energy it absorbs, the more it heats.
i think with water it's the same. if you have coloured water, for example dark blue, this colour can absorb more light = thermal energy than for example yellow coloured water.

for the speed of gaining thermal energy... hm. you need to know some physic and chemical basic knowledge to understand and I'm not sure i can explain them to you so clearly..
my explanation above is also not really good.. I hope you understand!
greets
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[Lorikeet]

Wow, I'm impressed at your explanation. Thanks, Stellara

[stellara]

no poblem i hope it's all right, though...
greets
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Don't cry because it's over - smile because it happened!

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[NMO2]

Thanx so much..... that actually helped a lot!!! Thank you thank you thank you!!!!!!!!!
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Natalie

[admiral]

Although this topic is over, I still want to give my opinions about it.

Why does light colour absorb less energy than dark colour? That mirrors reflect light, I can understand. I can't understand why it should happen to colours, because the material constant of water doesn't change with the colourchanging, right? I know that I have to test it with running around on a sunshine day with black pullovers and white pullovers, but why?

I'm a theorist, you should know.

Look, eyes are stimulated by the electromagnetic radiation. Our eyes have rods (St�bchen) and cons (Zapfen). The rods let us see black-white contrasts, and the cons let us see the colours. The rods for red is stimulated by a long wave length, green for a medium and blue for a short one.


So the colors are dependent from the wave lengh. And from a longer wave lengh, I think it's simple to derivate the energy absorbtion of the "warm" colours. Lambda (wavelengh) = phase velocity/ frequency of wave.

And so, I guess your question is answered.
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If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you"

[admiral]

Sorry, I haven't told all as I was to tired this morning.
As we know that lambda = c * f, we also know that the frequency is
f= c/ lambda

So lambda, as I showed you the last time, is antiproportinal to the frequency. The higher lambda is, the longer the wave will be.

According to the quanta theories, the energy of radiation, for example light radiation, is E= h *f (the constant h is the "Planck'sche Wirkungsquantum", hmmm...) h= 6,62 * 10^-34 J*s

And that is the prove that a short wave lengh saves more energy than a long wave lengh.
_________________
If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you"

[stellara]

you're absolutely right, but how do you explain that for example red coloured water absorbs more heat than for example yellow coloured water? red electromagnetic waves have a longer wave-length than yellow ones. so the energy they contain is because of E = h*c/λ (λ is lamda, the symbol for wave-length) is higher than the energy of the yellow waves.

it is totally right what you explain though it has not much to do with the question i think. the question was why different coloured water can differently absorb energy from (I assume white) light. It's not about light and it's different colours, but about objects with different colours which can differently absorb energy.

hmm, although, it would be funny to see how for example yellow coloured water absorbs energy that comes one time from yellow light, then from red light and from violet light. and then change the water's colour and make the experiment once again and compare

greets
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Don't cry because it's over - smile because it happened!

MOKEY ROCKS!!!

[asterix]

Objects appear dark because they absorb light instead of reflect it. When light is absorbed by a dark object, the energy carried by the light doesn't just disappear, it raises the energy of the object doing the absorbing ( In this case, small particles of colour pigment suspended in water). The object, in turn, releases the absorbed energy by emitting infrared (heat).

The darker the object, the better its emission of heat because it is a better
absorber of light.

[stellara]

hey asterix! nice to hear from you again!!
yep, that's what I wanted to say you have found a clearer way of explaining it
greets and I hope you'll have a good start in the new year 2006!!!
_________________
Don't cry because it's over - smile because it happened!

MOKEY ROCKS!!!

[admiral]

heyhey, I thought it was clear, isn't it?
You only say that darker colours absorb more light than lighter ones, without any explanation.
And according to the fact that statements without reasons are stupid, I only wanted to show what I thought was exactly responsible for the light absorbtion.

As you said, that energy is proportional to light, I thought that different colours must have to do something with the light absorbtion.

And as you already said, we only perceive something as red. But the reason why something is red is because of it's wave lengh. See the nice diagram for which I searched very very long at 7:02 pm, friday 30th.

That was the prove of lambda=c*f, and from the diagram, you can see that

[admiral]

Listen, I'm trying to explain why ultraviolet colours are better absorbers than infrared colours, and not only telling you that it is so. And next time I will explain to you what this has to do with black and white. Or stellara can do it with http://www.seilnacht.com/Lexikon/Farbe.htm

It's all about mixing colours, with aqua colours, and that mixing light is the other way round. However, black and white are extrme points.
_________________
If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you"

[NMO2]

Thanks very much!!! is there a way to get that site in english?? You guys have been so helpful!! THANKS AGAIN!!!
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Natalie

[admiral]

I haven't found.
But it's really not a problem. Look, you have also painted in your childhood. And the more colors you mix together, the darker this will be, right?
And with light, it's the opposite. So, the more colors light contain, the whiter it will be.

A white light is a mix of the red light (which has a long wave length) and the violet light. (with a short wave length).

Light water absorb light colors of the light with long wave lengh. (infrared)
Dark water absorb dark colors with a short wave lengh. (ultraviolet)

That's why dark water absorbs more energy than light water.

That's really all behind it. You don't need an english site for tihs.
_________________
If I say "I love you" to someone, then I also have to say "I love inside you everyone else. I love the whole world because of you. I also love myself inside you"

[stellara]

ah, you mixed up a few things