# The electron volt

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

## Answers and Replies

Doc Al
Mentor
The electron volt can be defined as mass, temp and energy.
The electron volt can be used to define units of mass, temp, and energy.

How can something with such small energy and mass exhibit such high temperature?
It's not a 'thing'; it's a unit of measure that proves convenient in the right context.

• sophiecentaur
Khashishi
Science Advisor
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.

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.

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?

Khashishi
Science Advisor
I already answered that...

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.

Thanks man.

I already answered that...

I think I'll call you speedy Doc Al
Mentor
Electron volt is a noun, i.e. a person, place or thing.
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.

Besides being useful, how can an energy of 1.6022 x 10-19 J be equivalent to a temperature of 1.160 x1011 K?
How the eV can be used to measure temperature and mass, nicely summarized by Khashishi, is covered in the wiki page for electron volt.

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.