# Homework Help: Radiation - energy states

1. Aug 24, 2011

### mstud

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

The figure (see attachment) shows part of a energy-state-diagram for an atom. Three energy states are included. At energy transition 1 & 2 the atom emit radiation with the wavelengths of $2.56 \cdot 10^{-8} m$ and $3.04 \cdot 10^{-8} m$, respectively.

Find the wavelength for the radiation which is emitted at transition 3.

2. Relevant equations

N/A

3. The attempt at a solution

I tried to take wavelength 1 minus wavelength 2, but this gave a completely wrong answer.

I got 4.8 nm. But the answer should be 162 nm.

How shall I then solve it? Does it make any difference to calculate the energy of the two transitions and find the difference between them, or will that give me the same weird answer?

ANY ideas?

Thanks

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2. Aug 24, 2011

### PeterO

You can only subtract energy - the difference between energy levels.

You need to convert the wavelengths to energy, subtract the energies, then convert the answer back to a wavelength

3. Aug 24, 2011

### mstud

Thought of doing so but I didn't know if it was the right way.

Thank you , know I both got the right answer and know how to do it next time ...