The electron - couple questions

[DiracPool]

The electron -- couple questions

Couple questions on the electron: First, as an accelerating charged body, an electron radiates electromagnetic energy in the form of photons (wiki). But I learned that photons are only emmited when an electron transitions energy states. It would seem to still be accelerating in its orbital even when staying in the same energy state. So why not continue to radiate photons while remaining in the same energy state?

Two, is the spin of an electron an inherent characterisitc of THAT particluar electron, or can the spin of any given electron switch from, say, up to down? In other words, is it a mechanical property of its motion, like a spinning ball, or is it a structural characteristic of the particle itself, like chirality in identical molecules?

 

[dextercioby]

There's no concept of <accelerating charged body> in quantum theory, this is entirely classical, so that you should have written <as an accelerating charged body, an electron radiates electromagnetic energy> without the <...in the form of photons>.

 

[andrien]

As for your second question.spin of electron is a pure quantum mechanical attribute.It does not mean that it is spinning around certain axis.Every electron has a spin 1/2 ,it is not for any particular electron.You can not change the spin of any electron.

 

[jtbell]

All electrons have the same magnitude of intrinsic angular momentum ("spin"), namely

$$| \vec S | = S = \sqrt{s(s+1)} \hbar
= \sqrt{\frac{1}{2} \left( \frac{1}{2} + 1 \right) } \hbar
= \frac{\sqrt{3}}{2} \hbar $$

but they can be either "spin up" or "spin down", namely the component of $\vec S$ along any axis (usually called the "z-axis" for convenience) can be either $S_z = + \hbar / 2$ or $S_z = - \hbar / 2$. A particular electron can have its spin "flipped" from "up" to "down" or vice versa, but the magnitude remains the same.

 

[DiracPool]

Thank you all for the responses