# Free space (electromagnetism)/Related Articles

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## Parent topics

## Subtopics

- Electromagnetism [r]: Phenomena and theories regarding electricity and magnetism.
^{[e]} - Vacuum (science) [r]: A realizable vacuum with a gaseous pressure that is much less than atmospheric.
^{[e]}

- Coulomb's law [r]: An inverse-square distance law, like Newton's gravitational law, describing the forces acting between electric point charges; also valid for the force between magnetic poles.
^{[e]} - Electric constant [r]: A physical constant in the International System of Units (SI) relating capacitance to area in classical vacuum with an exact value
*ε*= 10_{0}^{7}/(4πc_{0}^{2}) F/m,*c*being the defined value for the speed of light in classical vacuum in the SI units._{0}^{[e]} - Electromagnetic wave [r]: A change, periodic in space and time, of an electric field
**E**(**r**,t) and a magnetic field**B**(**r**,t); a stream of electromagnetic waves, referred to as electromagnetic radiation, can be seen as a stream of massless elementary particles, named photons.^{[e]} - Heisenberg Uncertainty Principle [r]: The quantum-mechanical principle that states that certain pairs of physical properties cannot simultaneously be measured to arbitrary precision.
^{[e]} - Maxwell equations [r]: Mathematical equations describing the interrelationship between electric and magnetic fields; dependence of the fields on electric charge- and current- densities.
^{[e]} - Speed of light [r]: A physical constant
*c*describing the speed of electromagnetic radiation in vacuum. In the International System of Units the metre is the distance light travels in classical vacuum in 1/*c*seconds, using the defined value*c = c*≡ 299 792 458 m/s (exact)._{0}^{[e]}