# Homework Help: MeV to Joules Units : How? 'In Electricity'

1. Jun 21, 2006

### Spirit

So Hi,

how you transfer from MeV to Joules?

Thx, Exam this Friday :)

2. Jun 21, 2006

### nrqed

One electronvolt is defined to be the kinetic energy acquired by an electron accelerated through a potential difference of one volt so

$$1 eV = 1.602 \times 10^{-19} J$$

(basically, the numerical constant is the elementary charge. The above expression is obtained by multiplying the absolute value of the charge of an electron by a optential difference of one volt, hence the name "electron-volt").

And one MeV )mega electronvolt) is a million times that

3. Jun 22, 2006

### ek

To go from MeV to J you multiply by 1.6E-13. To go the other way you just divide by that same number.

Of course that's very specific. In general, it's more practical to simply remember the definition of the electron volt as 1.6E-19 J and go from there.