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    Query 1: This thread refers when a molecule changes state. Okay so when a molecule melts or evaporates, there is a decrease in molecular potential energy and hence there are more collisions but the temperature does not rise. This is the part that gets me a little, cause of course energy cannot be destroyed nor created so it has to be given out in terms of heat to the surroundings, or provided to keep the potential energy between the molecules?

    Query 2: When the molecule condenses or solidifies there is a decrease in kinetic energy and therefore a increase in potential energy but the temperature does not fall. Again is heat given out to the surroundings here?

    Thanks in advance
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    Just a thought, but based on kinetic thoery, is the kinetic energy not, in fact, the heat energy?
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    (Original post by SOTEK)
    Just a thought, but based on kinetic thoery, is the kinetic energy not, in fact, the heat energy?
    It requires movement of the molecules in order to generate the heat, yeah.
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    (Original post by boromir9111)
    It requires movement of the molecules in order to generate the heat, yeah.
    I may be completely wrong here, but thinking along the lines of collisions, the temperature doesn't rise because the increased collisions simply means the energy is spread around the substance, not staying with that same molecule.
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    (Original post by SOTEK)
    I may be completely wrong here, but thinking along the lines of collisions, the temperature doesn't rise because the increased collisions simply means the energy is spread around the substance, not staying with that same molecule.
    So yeah, the energy is provided in order to increase the potential energy of the substance(not molecule as i was saying lol)????
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    (Original post by boromir9111)
    So yeah, the energy is provided in order to increase the potential energy of the substance(not molecule as i was saying lol)????
    I'd go for the idea that it's a transfer between potential and kinetic, so yes, I think you've just about got it nailed down there, if you're saying what I think you're saying, and I am too...
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    (Original post by SOTEK)
    I'd go for the idea that it's a transfer between potential and kinetic, so yes, I think you've just about got it nailed down there, if you're saying what I think you're saying, and I am too...
    Yeah exactly, there is a transfer between the two and we know that due to the first law of thermodynamics - energy can neither be created nor destroyed only transferred. Thanks for that mate.

    I have another question but this is relating towards "redshift" i know what it is, the longest wavelength produced from a radiation source (a planet) and therefore a low frequency. But i am concerned with the process that occurs in order to see that light cause i need to know that. Has it got to do with the absorption of light?
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    (Original post by boromir9111)
    Yeah exactly, there is a transfer between the two and we know that due to the first law of thermodynamics - energy can neither be created nor destroyed only transferred. Thanks for that mate.

    I have another question but this is relating towards "redshift" i know what it is, the longest wavelength produced from a radiation source (a planet) and therefore a low frequency. But i am concerned with the process that occurs in order to see that light cause i need to know that. Has it got to do with the absorption of light?
    Redshift? I'm pretty certain that's the doppler effect, as the light source moves away at speed, the faster it's going away from the observer, the longer the wavelength appears to be.
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    (Original post by SOTEK)
    Redshift? I'm pretty certain that's the doppler effect, as the light source moves away at speed, the faster it's going away from the observer, the longer the wavelength appears to be.
    Yeah i know about Doppler effect inside out but i also need to know about how we are able to see this "redshift" it's due to each atom having it's own unique light that it emits due to a drop in energy levels and release a photon. Is that on the right lines?
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    (Original post by boromir9111)
    I have another question but this is relating towards "redshift" i know what it is, the longest wavelength produced from a radiation source (a planet) and therefore a low frequency. But i am concerned with the process that occurs in order to see that light cause i need to know that. Has it got to do with the absorption of light?
    If, by redshift, you mean the effect where the wavelength of light emitted from stars is shifted towards the red (becomes longer); it's caused by the motion of the star away from the observer, and is the Doppler Effect. It is not caused by absorption.
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    (Original post by Stonebridge)
    If, by redshift, you mean the effect where the wavelength of light emitted from stars is shifted towards the red (becomes longer); it's caused by the motion of the star away from the observer, and is the Doppler Effect. It is not caused by absorption.
    Yeah i know, read my above post please.
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    (Original post by boromir9111)
    Yeah i know about Doppler effect inside out but i also need to know about how we are able to see this "redshift" it's due to each atom having it's own unique light that it emits due to a drop in energy levels and release a photon. Is that on the right lines?
    Not really. It's all the doppler effect, the wavelength simply appears longer, and due to the fact that wavelength is what the observer recognises as colour, that's all that redshift is.
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    (Original post by SOTEK)
    Not really. It's all the doppler effect, the wavelength simply appears longer, and due to the fact that wavelength is what the observer recognises as colour, that's all that redshift is.
    Doppler shift is the effect of an objects radial velocity on the Wavelength.If the object is closer to spot X or is coming toawrds that spot, it will be blue-shifted that is more frequency in the waves and vice versa for an object moving away with respect to the observer. =)
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    (Original post by ibysaiyan)
    Doppler shift is the effect of an objects radial velocity on the Wavelength.If the object is closer to spot X or is coming toawrds that spot, it will be blue-shifted that is more frequency in the waves and vice versa for an object moving away with respect to the observer. =)
    Thankyou, that's a better technical explanation of the point.
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    Okay but that doesn't explain the colour it EMITS out.... how does that work? that surely can't be doppler effect?
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    (Original post by boromir9111)
    Okay but that doesn't explain the colour it EMITS out.... how does that work? that surely can't be doppler effect?
    Actually, it is. The emission itself doesn't change, but as soon as it is emitted, that is to say, even as it is being emitted, the doppler effect begins to take effect. Perhaps think of a un being shot from a moving train, the gun has not changed, the bullet has not changed, but due to the train's velocity, even as the bullet is emitted from the barrel, relative to the world outside the train it's velocity is affected by the train's velocity, but relative to the barrel it has just left, it's velocity is exactly as if the whole thing had been stationary. Apologies if this seems an odd explanation, it's the best I could think of.
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    (Original post by SOTEK)
    Actually, it is. The emission itself doesn't change, but as soon as it is emitted, that is to say, even as it is being emitted, the doppler effect begins to take effect. Perhaps think of a un being shot from a moving train, the gun has not changed, the bullet has not changed, but due to the train's velocity, even as the bullet is emitted from the barrel, relative to the world outside the train it's velocity is affected by the train's velocity, but relative to the barrel it has just left, it's velocity is exactly as if the whole thing had been stationary. Apologies if this seems an odd explanation, it's the best I could think of.
    That makes complete sense what you're saying but i don't think i am making my point clear and that's my bad on side. But thank you very much for your help mate, you've helped me alot!!!!
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    (Original post by boromir9111)
    That makes complete sense what you're saying but i don't think i am making my point clear and that's my bad on side. But thank you very much for your help mate, you've helped me alot!!!!
    You're welcome, if anything else pops up, don't hesitate to ask.
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    (Original post by boromir9111)
    Yeah i know about Doppler effect inside out but i also need to know about how we are able to see this "redshift" it's due to each atom having it's own unique light that it emits due to a drop in energy levels and release a photon. Is that on the right lines?
    If you understand the Doppler Effect, then you will understand that it doesn't actually matter how the light is emitted from the object. There just needs to be some light in the 1st place.
    Now you are probably thinking about the effect as observed in stars or galaxies that are moving rapidly away from us.
    In these cases, the red shift is measured by looking at the characteristic wavelengths emitted or absorbed by the stars. These wavelengths have known values and can even be observed in the laboratory on Earth. When the same emissions are observed in distant stars, the characteristic wavelengths are longer than expected. I.e. shifted to the red.
 
 
 
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