Why each energy state is having only 1 electron?

[Sampad Saha]

Why each energy state is having only 1 Fermion or electron instead of 2?
as we know fermions or electrons obey pauli's exclusion principal so 1 state can have two electrons with different spin (i.e if one spins up then second spins down) isn't it?

 

[jfizzix]

Each orbital can hold two electrons because they have two different spin states. The complete state of both electrons is not identical, so Pauli's exclusion principle doesn't prevent two electrons with different spin states from occupying the same orbital.

 

[Sampad Saha]

Each orbital can hold two electrons because they have two different spin states. The complete state of both electrons is not identical, so Pauli's exclusion principle doesn't prevent two electrons with different spin states from occupying the same orbital.

Ya...I know 2 electron can occupy 1 energy state. But in Fermi-Dirac statistics there is mentioned that "only one electron can occupy one energy state"...!

 

[jfizzix]

Fermi-Dirac statistics say that only one electron can occupy one quantum state.

The complete quantum state of an electron would include both its energy state and its spin state, so there's no conflict.

 

[jfizzix]

Note that there is a factor of two in describing Fermi-Dirac statistics in the context of thermodynamics and such.