when an electron revolves in orbits then why they do not loss energy?

Answer 1

Only a motion disturbed loses energy, a stable orbit has no energy loss.

Answer 2

A planet in circular orbit around a star is a stable system. No energy change takes place. With an elliptical orbit, there is some interchange between potential and kinetic energy, but the total is conserved. A satellite orbiting earth has some atmosphere to deal with, so their orbits decay.

An electron orbiting a nucleus has no atmosphere to deal with. However, the time-varying electric field associated with its motion should induce a magnetic field, and result in energy being lost to the emitted electromagnetic wave. But now add the quantum constraint that the length of the orbit must be an integral multiple of the wavelength of the electron's wavefunction. That means the orbit can't experience continuous decay. Instead, an electron can drop from a higher energy orbit to a lower one, emitting in the process a photon whose energy is the energy difference between the two orbits. This accounts for the discrete emission spectrum of elements.

Exactly what happens while the electron is 'waiting' to drop to that lower energy orbit is beyond my understanding of quantum mechanics.

Answer 3

As per Maxwell any accelerated charged particle must radiate energy by emiting electromagnetic waves....
1.This means that the electron which is a charged particle revolving aroud the nucleus in an orbit must also do the same and lose energy and thus thus revolve in spiral path and thus fall in the nucleus....
2.Now the frequency of radiation of ecectromagnetic waves is directly proportional to frequency of revolution of the charged particle and hence when the electron will rotate in spirals its frequency of revolution increases and thus frequency of radiation of ecectromagnetic waves increases....
3.But this must give rise to a continuous spectrum..of the atom but instead we observe a line spectrum...also we know that no electron falls in the nuclues as this would destroy the nuclear stability ...which means that the above electrons do not lose energy while revolving and thus to explain this Neils Bohr stated the electrons revolve only in those orbits where the angular momentum is an integral multiple of h/2pie.......
Thus is the required explanation..
Thanks

Answer 4

They have to move or the attraction will pull the - and + together which would not work at all, obviously. They maintain a balance in their shell situation like little moons and satellites around their little planets (funny how nature has a pattern it employs). It is balance with no loss, as the size and composition of an electron precludes any loss, for any of the smaller component parts of the electron must always be there, or it becomes something different, no longer the electon on an element's atom, no longer the element.

Answer 5

To the other posters - Come on people, haven't you heard of Quantum Mechanics? Newtonian physics don't apply at the atomic and subatomic level
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You're right, khattak - applying the laws of Newtonian physics, the orbit of an electron should degrade and it should fall into the nucleus. The fact that it doesn't is exactly why Quantum Mechanics exists. The laws of Newtonian physics don't work with atomic and subatomic particles.

Quantum Mechanics doesn't describe electrons as moving as another poster put it "like little planets and satellites". Rather, an eletctron is described as having a probability of existing somewhere in a shell around the nucleus.

Wikipedia will give you a very cursory description of Quantum Mechanics - http://en.wikipedia.org/wiki/Quantum_mechanics

If you want to learn more, the book Quantum Mechanics for Dummies is a good starting point.

Answer 6

They do! In an excited atom the electrons are not all in their lowest state so the electrons do lose energy by falling into lower states -- the energy is emitted as photons. This is how the light from your computer screen is produced. However, in quantum mechanics, electrons can only stay in fixed orbits and cannot lose any more energy when they are in the lowest state.

Answer 7

The analogy that an electron moves around the nucleus, rather as a planet moves round a star, is an oversimplification of an electron's motion.

Answer 8

Every atom contains electrons which move at the speed of light. An atom from a million year old dinosaur bone still contains these electrons which have never slowed down. I can't explain it without invoking God, which seems to really bother a lot of people who use Yahoo Answers.

Answer 9

and since there is little smaller than it, it has no friction to disrupt it...