Planck charge

In physics, the Planck charge is the natural unit of electric charge, denoted by <math>q_p<math>. It is defined as

<math>q_p = (2ch\epsilon_0)^\frac{1}{2}<math>

where :

c is the speed of light in a vacuum,

h is Planck's constant,

<math>\epsilon_0<math> is the permittivity of free space.

Its value as expressed in SI units is

<math>q_p<math> = 1.875 × 10⁻¹⁸ C.

It is equal to the recriprocal of the square root of the fine structure constant (about 11.7) times the charge on an electron, ignoring the sign.