Homework Help: V and eV question

1. Jan 23, 2008

dangsy

1. The problem statement, all variables and given/known data
Light of the wavelength Lambda = 5893 Angstrom is incident on a surface. The stopping potential for the emitted electrons is 0.36 volt. Calc the max energy of the photoelectron, the work function and threshold frequency.

my question is about the stopping potential, the problem is given in volts, how do I convert to eV? does "emitted electrons" indicate it as an Electron volt in words, so that the eV would be 0.36?

Thanks!

2. Jan 23, 2008

blochwave

Well volts and eV are fundamentally different

an eV is energy, you could, for example, express it in joules if you wanted to

a volt is a unit of potential difference

An eV is how much energy an electron would have after being accelerated across one volt of potential difference

3. Jan 23, 2008

dangsy

If I took the 0.36V and multiplies by e = (1.6E-19) would that give me an eV? I'm also not understanding your explanation very well, is there any other way to put it?

Thanks!

4. Jan 23, 2008

mda

Yes, that tells you how many Joules in 0.36eV.

5. Jan 23, 2008

dangsy

so...just to make sure...

if I'm given volts I can multiply by e (1.6E-19) to get eV?

so 0.36V x 1.6E-19 = 5.76E-20eV?

Thanks!

6. Jan 23, 2008

mda

No, 0.36eV = 5.76E-20 J

7. Jan 23, 2008

dangsy

But if the problem gives Volts as in "The stopping potential for the emitted electrons is 0.36 volt"

how do I get eV out of this?

8. Jan 23, 2008

mda

Then the electron energy associated with this potential is 0.36eV, which as you have shown is 5.76E-20 J. Generally energy = charge * potential.