# Energy of an electron

## Main Question or Discussion Point

Suppose we have 3 equipotential surfaces V1 V2 & V3(V1>V2>V3) and an electron residing in second surface and roaming freely with kinetic energy say K.E. Now if our K.E is greater than e(V1-V2) will the electron jump to the top surface with decreased kinetic energy? On the other hand will it jump to the lower state?If none of the above happens how will an electron jump to higher states if we provide external energy(as in the case of energy bands)?

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tiny-tim
Homework Helper
welcome to pf!

hi ajith.mk91! welcome to pf!
Suppose we have 3 equipotential surfaces V1 V2 & V3(V1>V2>V3) and an electron residing in second surface and roaming freely with kinetic energy say K.E. Now if our K.E is greater than …
it can't have any KE …

compare it with a body orbiting the Earth at a particular radius …

to do so it must have a particular speed (and KE) …

it stays on that equipotential surface not because the potential is constant, but because its gradient exactly matches its KE

same for an electron in an electromagnetic field

Do you mean to say that both PE and KE are interrelated? If they are,which law governs their relation?
And secondly what is meant by KE of a hole in the valence band. Is it the KE of incoming electron?

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tiny-tim
Homework Helper
hi ajith.mk91 !
Do you mean to say that both PE and KE are interrelated? If they are,which law governs their relation?
not exactly

yes, KE and PE are related by the law KE + PE = constant (or = work done if there's some external force)

no, they aren't related to what we were talking about … the relation needed for that is between the centripetal acceleration (which happens to be proportional to KE) and the gravitational or electric force (not potential)
And secondly what is meant by KE of a hole in the valence band. Is it the KE of incoming electron?
sorry, not my field, never heard of it