Electron volt

The AP Physics 2 and AP Physics C: Electricity and Magnetism tables both print $1\ \text{eV} = 1.60 \times 10^{-19}\ \text{J}$.

Where the number comes from is worth seeing once, because it settles the confusion in the name. Energy and potential difference are linked by $\Delta U_E = q\,\Delta V$. Put in one elementary charge, $e = 1.60 \times 10^{-19}\ \text{C}$, and one volt, and the energy is $1.60 \times 10^{-19}\ \text{J}$. The unit is a charge times a voltage, and charge times voltage is energy. An electron volt is no more a voltage than a kilowatt hour is a power.

It exists because joules are an awkward size for single particles. Visible photons carry a few eV, and atomic ionisation energies run to tens of eV. The AP Physics 2 sheet supports working directly in these units, printing $h = 4.14 \times 10^{-15}\ \text{eV}\cdot\text{s}$ alongside the value in joule seconds, and $hc = 1240\ \text{eV}\cdot\text{nm}$. That last one is the shortcut worth memorising: a $500\ \text{nm}$ photon carries $1240/500 = 2.48\ \text{eV}$.

Two traps. Convert to joules before using any equation that mixes in kilograms and metres, such as $K = \tfrac{1}{2}mv^2$. And $\text{MeV}/c^2$, as in $1\ \text{u} = 931\ \text{MeV}/c^2$, is a unit of mass, not energy.