Loading [MathJax]/jax/output/HTML-CSS/jax.js
Skip to main content
Library homepage
 

Text Color

Text Size

 

Margin Size

 

Font Type

Enable Dyslexic Font
Engineering LibreTexts

13: Physical Constants

( \newcommand{\kernel}{\mathrm{null}\,}\)

The speed of light in free space (c), which is the phase velocity of any electromagnetic radiation in free space, is 2.9979×108 m/s. This is commonly rounded up to 3×108 m/s. This rounding incurs error of 0.07%, which is usually much less than other errors present in electrical engineering calculations.

The charge of an electron is 1.602×1019 C. The constant e+1.602176634×1019 C is known as the “elementary charge,” so the charge of the electron is said to be e.

The permittivity of free space (ϵ0) is 8.854×1012 F/m.

The permeability of free space (μ0) is 4π×107 H/m.

The wave impedance of free space (η0) is the ratio of the magnitude of the electric field intensity to that of the magnetic field intensity in free space and is μ0/ϵ0376.7 Ω. This is also sometimes referred to as the intrinsic impedance of free space.

Boltzmann’s constant is 1.381×1023 J/K, the amount of energy associated with a change of one degree of temperature. This is typically assigned the symbol k (unfortunately, the same symbol often used to represent wavenumber).


This page titled 13: Physical Constants is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Steven W. Ellingson (Virginia Tech Libraries' Open Education Initiative) via source content that was edited to the style and standards of the LibreTexts platform.

Support Center

How can we help?