- #1
Tranceform
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The following text is an excerpt from a physics book:
I find this paragraph a bit hard to grasp, so I have some questions about it and I would appreciate if they are clarified.
1) What is meant by "the energy carried off by the radiated electromagnetic waves"? As I interpret this it means the energy that are within (travelling) electromagnetic waves. Right? (I think the word "off" confuses me, why not just say "carried BY"?)
2) What does it mean that the energy is "lost"? As energy can't be destroyed but only transformed, what is it transformed into?
3) As I understood a a perfect blackbody, it is a body which absorbs AND re-emits all electromagnetic waves that are incident on it. But if the body re-emits everything that is incident on it, how can the object both gain (absorb) this energy and at the same time re-emit it? That would mean it duplicated the energy? Or does it only absorb half the incident energy and re-emits the other half?
4) Are "the energy carried off by the radiated electromagnetic waves" and "the energy lost by the atomic oscillators" always identical? Or only so for a perfect blackbody?
5) Is there some other energy form involved in this situation that is not mentioned here?
Conservation of energy requires that the energy carried off by the radiated electromagnetic waves must equal the energy lost by the atomic oscillators in Planck’s model. Suppose, for example, that an oscillator with an energy of 3hf emits an electromagnetic wave. According to Equation 29.1*, the next smallest allowed value for the energy of the oscillator is 2hf. In such a case, the energy carried off by the electromagnetic wave would have the value of hf, equaling the amount of energy lost by the oscillator.
* E = nhf, n = 0,1,2,3,...
I find this paragraph a bit hard to grasp, so I have some questions about it and I would appreciate if they are clarified.
1) What is meant by "the energy carried off by the radiated electromagnetic waves"? As I interpret this it means the energy that are within (travelling) electromagnetic waves. Right? (I think the word "off" confuses me, why not just say "carried BY"?)
2) What does it mean that the energy is "lost"? As energy can't be destroyed but only transformed, what is it transformed into?
3) As I understood a a perfect blackbody, it is a body which absorbs AND re-emits all electromagnetic waves that are incident on it. But if the body re-emits everything that is incident on it, how can the object both gain (absorb) this energy and at the same time re-emit it? That would mean it duplicated the energy? Or does it only absorb half the incident energy and re-emits the other half?
4) Are "the energy carried off by the radiated electromagnetic waves" and "the energy lost by the atomic oscillators" always identical? Or only so for a perfect blackbody?
5) Is there some other energy form involved in this situation that is not mentioned here?