# Homework Help: Need some help please

1. Sep 16, 2008

### caseman

I am searching for some answers to some physics questions, can you help?

My back is against the wall, willing to accept a small challenge gang? Thanks again...

1. Calculate the energy in joules of photons of light with frequency 6.00 × 1014 Hz.
2. Calculate the frequency in hertz of photons of light with energy of 2.00 × 10-19 J
3. Calculate the energy En (in electron volts) of a hydrogen atom’s electron with n = 5.
4. Calculate the radius in nanometers of the orbit of a hydrogen atom’s electron with n = 5.
5. If the energy of n = 4 is −0.85 eV and that of n = 2 is −3.40 eV in a hydrogen atom, a transition from n = 4 to n = 2 will release a photon of what energy?
6. Calculate the energy in electron volts of the photon emitted when an electron in a hydrogen atom goes from n = 2 to n = 1.
7. Calculate the de Broglie wavelength for an electron (m = 1 × 10-31 kg) moving at 2.4 × 106 m/s.
8. Calculate the de Broglie wavelength of a 0.145-kg baseball moving at a speed of 45.2 m/s.
9. Calculate the energy En (in eV) and the radius in nanometers of a hydrogen atom’s electron with n = 6, using Bohr’s model.
10. If the energy of n = 6 is −0.378 eV and that of n = 4 is −0.850 eV in a hydrogen atom, a transition from n = 6 to n = 4 will emit a photon of what energy?

2. Sep 16, 2008

### danago

Have you tried reading a textbook or searching for anything? What equation do you know that relates the energy of a photon to its frequency. If you dont know of one, try googling it.

3. Sep 16, 2008

### Melawrghk

Those are really simple one-line calculation questions I'm sure you can do. I recommend you take a look at your Physics formula sheet.
The first question is easy to figure out with E=hf, same with second.. Just trying reading your book/notes.

4. Sep 16, 2008

### caseman

Thanks for the note..you've got a great point. I am trying to help my son out a bit..he has not exactly been doing a great job in school. Probably not the most responsible thing to do but I am just trying to get some quick answers for him.

I guess at the end of the day he needs to understand the concepts himself otherwise he will not do well on the exams...I was hoping to get someone to give the formulas and explanations then review them with him..I can do the math but it has been 25 years since I studied physics and I have long forgotten the formulas and relationships.

Thanks again!