Elementary charge

Reader's Guide

The elementary charge is a cornerstone of modern physics, serving as the unit of electric charge in natural unit systems such as atomic units. Later, the name 'electron' was assigned to the particle, and the unit of charge e lost its name, though the unit of energy electronvolt (eV) remains a remnant. All known elementary particles have charges that are integer multiples of the charge on the down quark, an observation known as charge quantization, though the physical cause is not known and has no explanation in the Standard Model. Quarks have quantized charge in multiples of e/3 but cannot be isolated. Quasiparticles in the fractional quantum Hall effect exhibit fractional charges but are not considered a violation of charge quantization.

Did You Know?

• All known elementary particles have charges that are integer multiples of the charge on the down quark, an observation known as charge quantization.
• Quarks have quantized charge in multiples of e/3 but cannot be isolated; stable groupings of quarks all have charges that are integer multiples of e.