# Probability of a wave function

1. ### soul

62
Hi everyone,

Assume that we have an electron in the Coulomb field of a proton, whose wave function is specified. How can I find the probability of finding this electron in the ground state of the hydrogen atom?

Thank you.

2. ### malawi_glenn

4,726
find the projection of that given wave function with the wave function of ground state for hydrogen.

3. ### soul

62
Why do we do that? I couldn't understand the reason.

4. ### malawi_glenn

4,726
It is the formalism of quantum mechanics?

Think of vectors in the plane, wavefuctions are vectors in Hilbert space.

The probability for state |a> to be in state |b> is given by: |<a|b>|^2