0
$\begingroup$

Suppose an electron in the 2nd shell gets excited and jumps to the 4th shell. Shouldn't the electron then exist in an unstable equilibrium in the 4th shell, than lose energy and drop down to the 2nd shell? What causes it to come out of the equilibrium position and lose energy? The teacher who gave me this problem to think about said that quantum mechanics plays a role in this. Can anyone please give an explanation?

$\endgroup$
  • 4
    $\begingroup$ Why does a stone fall to the ground, rather than just sit comfortably in the air? $\endgroup$ – Ivan Neretin Oct 9 at 19:15
  • 3
    $\begingroup$ In order for the excited state to decay it needs to be perturbed. An excited isolated system in vacuum can decay to a lower state by spontaneous emission which is caused by the fact that on very short times scales the vacuum is not empty. The energy-time uncertainty locally allows for large energies in a short time. In fact, so much energy that a electron-positron pair can be formed and annihilated during this short time. These vacuum fluctuations induce the decay. $\endgroup$ – Paul Oct 9 at 19:45
  • 3
    $\begingroup$ @IvanNeretin I don't think that's the right picture. After all, one could instead ask 'why does a stone fall off the mountain, rather than staying at the peak?'. The answer is that in fact they don't spontaneously fall off the peak—some can rest there for centuries or more; to fall, they need to be perturbed. $\endgroup$ – theorist Oct 10 at 0:02
  • 2
    $\begingroup$ en.wikipedia.org/wiki/Spontaneous_emission $\endgroup$ – Buck Thorn Oct 10 at 7:48
0
$\begingroup$

The energy here is a kind of potential energy. By very nature, it always tries to stay minimum in magnitude, so it is said to have a "potential" to change its energy into other form of energy. Like stretch bow's potential energy change into (and transferred to) arrow's kinetic energy. in case of electron jumps, the energy transformed is in the form light.

$\endgroup$
  • $\begingroup$ As Ivan Neretin has also hinted at the concept with another example of potential energy $\endgroup$ – Aditya Oct 9 at 19:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.