# Simple question regarding spin

1. Dec 14, 2006

### land

Simple question regarding spin :)

1. The problem statement, all variables and given/known data

An electron is in spin state (superposition of spin eigenstates) given by the wavefunction: $$\chi=\frac{1}{3}\chi_+ + \frac{2\sqrt{2}}{3}\chi_-$$. I need to find the probabilities that a measurement would find the electron with spin up or spin down.

2. Relevant equations

Uh.. you just square the coefficients, right? :)

3. The attempt at a solution

Probably a silly question but this seems too easy. I don't have this as a formula anywhere in my notes or book.. but to find the probability of spin up, you just square (1/3), and to find the probability of spin down, it's just the square of 2sqrt(2)/3... right?

2. Dec 14, 2006

### OlderDan

If it's properly normalized, that will do it.

3. Dec 15, 2006

Thanks! :)