I keep reading that the Bohr model explained why the electron in orbit around the nucleus does not emit radiation even though it is accelerating. How does the Bohr model explain this?
Er.. the Bohr model does NOT explain why an electron "in orbit" around the nucleus does not emit radiation. While the Bohr-Sommerfeld quantization rule sort of "explains" this, there are still problems. This is because the Bohr model isn't correct! Electrons do not "orbit" the nucleus the way planets do around the sun. Refer to the solution to the Schrodinger equation for the hydrogen atom, for example.Moose352 said:I keep reading that the Bohr model explained why the electron in orbit around the nucleus does not emit radiation even though it is accelerating. How does the Bohr model explain this?
Albert Einstein was born within a few years of the completion of the Michelson Morely experiment. For his entire life the speed of light was known to be constant, and further, that there was no ether to propagate it. It was a known, but distressing, fact to all Physicists of the day. Einstein simply showed them how to square the constant velocity of Electro Magnetism with the rest of Mechanics.Think of the postulates that Albert Einstien proposed in his special theory of Relativty; stating that speed of light is constant if measured from any referance frame.
Theories or postulates , can turn out to be incorrect. Thats not the point. We are trying to state what exactly is a postlulate and what are the thoughts behind formulating one. Whether it turns out to be a correct one or not is a different story. Perhaps I was oversimplifying the idea of a postulate by saying you can assume "anything". But it is perfectly acceptable of a postulate to be contradictory and not accepted by a part of of physics and yet attempt to prove a phenomenon. The formulated postulates if true would go back and explain the contradictions.Integral said:Albert Einstein was born within a few years of the completion of the Michelson Morely experiment. For his entire life the speed of light was known to be constant, and further, that there was no ether to propagate it. It was a known, but distressing, fact to all Physicists of the day. Einstein simply showed them how to square the constant velocity of Electro Magnetism with the rest of Mechanics.
Einstein only postulated that which was already accepted Physics. It is a very dangerous thing to have a postulate which is not part of accepted Physics. It is that sort of thing that should be derived from known postulates. If your postulate are not understood, how can your results have meaning? Thus the questionable postulate of Bohr lead to an incorrect model.
Since I'm one of those who also said that the Bohr model is incorrect, and somehow, this was taken to be a sign of disrespect towards Bohr and his accomplishment, let me be clear that THAT was NEVER the intention. Pointing out the Bohr model was incorrect was meant towards those who STILL haven't gotten beyond the "planetary model" of an atom, as if our knowledge of this hasn't progressed beyond that. It wasn't a denigration of Bohr at all! Every ideas that we have in physics started out in the most naive, elementary, and restrictive form. Even the photoelectric effect model isn't correct if one were to view it today with our advanced electron analyzers. But this doesn't detract from the accomplishment of Einstein in enabling the opening of the door that led to this progress.reilly said:The problem of 1. atomic stability, and 2. discrete atomic spectra drove physicists absolutely nuts, until Bohr. His great insight was to accept as fact that "orbiting" electrons did not radiate. Given that, and acceptance of photons, as described by Einstein, Bohr was able to derive the formula for the Balmer series, and other hydrogen spectral series. Bohr started modern atomic physics, and, as a result, his work led to an explanation of the periodic table, and on-and-on.
To say that Bohr provided us with an "incorrect model", as suggested by Integral, is like saying the first motion pictures were 'wrong' because they did not have sound, or that Adam Smith was wrong because he did not anticipate modern economies, or that Newton was wrong, or Maxwell was wrong -- they never got to quantum effects. And, the planetary model of Rutherford was really wrong, yet it survived, if only as a metaphor.