# Homework Help: Energy uncertainty of an atom in an excited state

1. Dec 4, 2012

### Ezequiel

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

A Na atom is in an excited state for a mean time of $1.6 \times 10^{-8}s$. Then it jumps to the ground state emitting a photon with 2.105 eV of energy. Find the energy uncertainty of that excited state.

2. Relevant equations

3. The attempt at a solution

I don't even know where to start. Any help would be appreciated!

2. Dec 4, 2012

3. Dec 4, 2012

### Ezequiel

I just don't know how to use that to solve the problem. Could you be more specific?

4. Dec 5, 2012

### Ezequiel

Could it be $\Delta E > \frac{\hbar}{2} \frac{1}{\Delta t} = 32.96 \times 10^{-28}J$?

5. Dec 6, 2012

### sankalpmittal

Doesn't seem to be correct. What you did basically? And the question mentions Na atom , so we cannot use bohr equations. Also I don't know why they gave you energy of de-excitation. There is no use of it , I guess.... I think you used the correct equation but did not solve it correctly.

Last edited: Dec 6, 2012