Physical Constant

Key Stage 5

Meaning

A physical constant is a quantity which is believed to have the same value at all points in space and time.

About Physical Constants

Physical constants are found through measurement and therefore carry a level of uncertainty in their values. As a result much time is spent by physicists to reduce that uncertainty with more precise and accurate measurements.

The physical constants you should know of, but do not need to memorise are:

Physical Constant	Symbol	Value	Units
Elementary Charge	\(e\)	\(1.60\times10^{-19}\)	\(C\)
Rest Mass of a Proton	\(m_p\)	\(1.67\times10^{-27}\)	\(kg\)
Rest Mass of a Neutron	\(m_n\)	\(1.68\times10^{-27}\)	\(kg\)
Rest Mass of an Electron	\(m_e\)	\(9.11\times10^{-31}\)	\(kg\)
Gravitational Constant	\(G\)	\(6.67\times10^{-11}\)	\(Nm^2kg^{-1}\)
Permittivity of Free Space	\(\varepsilon_0\)	\(8.85\times10^{-12}\)	\(Fm^{-1}\)
Permeability of Free Space	\(\mu_0\)	\(4\pi\times10^{-7}\)	\(Hm^{-1}\)
Speed of Light in Free Space	\(c\)	\(3.00\times10^{8}\)	\(ms^{-1}\)
Planck's Constant	\(h\)	\(6.63\times10^{-34}\)	\(Js\)
Boltzman Constant	\(k\)	\(1.38\times10^{-23}\)	\(JK^{-1}\)