# B The electron volt

1. Apr 21, 2016

### Kevin McHugh

The electron volt can be defined as mass, temp and energy.

1 eV = 1.6022 x 10-19J

1 eV = 1.783 x 10-36kg

1 eV= 1.160 x 104K

How can something with such small energy and mass exhibit such high temperature? 104K is white hot

2. Apr 21, 2016

### Staff: Mentor

The electron volt can be used to define units of mass, temp, and energy.

It's not a 'thing'; it's a unit of measure that proves convenient in the right context.

3. Apr 21, 2016

### Khashishi

It's unfortunately confusing because physicists are lazy. Electron volts are really a measure of energy. But if you multiply temperature by Boltzmann's constant you get an energy, so if we (lazily) say the temperature is 0.03 eV, what we really mean is that temperature times $k_B$ is 0.03 eV.
If we measure mass in electron volts, we really mean the energy equivalent of the mass is in electron volts. $E = mc^2$ gives the energy equivalent for a mass.

4. Apr 21, 2016

### Kevin McHugh

Electron volt is a noun, i.e. a person, place or thing. Besides being useful, how can an energy of 1.6022 x 10-19 J be equivalent to a temperature of 1.160 x1011 K?

5. Apr 21, 2016

### Khashishi

6. Apr 21, 2016

### Kevin McHugh

Thanks man.

7. Apr 21, 2016

### Kevin McHugh

I think I'll call you speedy

8. Apr 21, 2016

### Staff: Mentor

You need to expand your definition of noun to include abstractions, such as units of measure. The idea that there is some "thing" called an electron volt that has the given mass and temperature is incorrect.

How the eV can be used to measure temperature and mass, nicely summarized by Khashishi, is covered in the wiki page for electron volt.

9. Apr 21, 2016

### David Lewis

In this context, electron actually means the amount of electric charge possessed by one electron or proton (a.k.a. an elementary charge), which is the same as 1.6 x 10-19 coulomb.

When you multiply charge by voltage, you get energy.