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Resistance is a measure of how difficult it is to pass an electric current through a conductor.

It is defined as the electromotive force needed to push a unit current through that conductor.

It is conventionally denoted $R$.



The usual symbol used to denote resistance is $R$.

Its $\LaTeX$ code is R .


The dimension of measurement of resistance is:

$\mathsf {M L^2 T^{−3} I^{−2} }$

This derives from its definition as:

$R = \dfrac {\text {EMF} } {\text {current} }$


The SI unit of resistance is the ohm $\Omega$: $1 \, \Omega = 1 \, \mathrm V \, \mathrm A^{-1}$

In the CGS unrationalised electromagnetic system, the base unit of resistance is the abohm $\mathrm {ab\Omega}$.

In the CGS unrationalised electrostatic system, the base unit of resistance is the statohm $\mathrm {stat\Omega}$.

Conversion Factors

\(\ds \) \(=\) \(\ds 1\) ohm
\(\ds \text {corresponds to}\) \(\) \(\ds 10^9\) abohm (or e.m.u. of resistance)
\(\ds \text {corresponds to (approximately)}\) \(\) \(\ds \dfrac 1 9 \times 10^{-11}\) statohm (or e.s.u. of resistance)

Also see

  • Results about resistance can be found here.