# Atomic Energy Levels

1. Aug 1, 2009

### physicsNYC

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

State the De Broglie Wavelength for electrons with an energy of 50eV

and

the following is a picture is a diagram of the energy levels in Fe:
What is the energy required to ionise Fe in in the ground state

2. Relevant equations
*lambda* = h/p = h/mv = h/sqr(2Em)

3. The attempt at a solution
for the first question i got 1.74x10^-10m but that is not the solution

and for the next question

is it -11.6 or +11.6

2. Aug 1, 2009

### rock.freak667

you mean

$$\lambda = \frac{h}{m \sqrt{2Em}}$$

did you remember to multiply by the mass again in the denominator?

We'd need to see the diagram to help you with the next part of the question.

3. Aug 2, 2009

### ideasrule

If it's "energy required", it's positive; in this case it makes no sense to talk about adding a negative amount of energy.