Scientific Ontology

R

Electromagnetism

Resistance

Opposition to the flow of electric current.

ohm (Ω)

Dimension: $[\,M L^2 T^{-3} I^{-2}\,]$

How values of resistance span the physical world (in Ω, log scale).

Copper wire

10^-2 Ω

Human body (dry)

10⁵ Ω

Glass insulator

10¹⁴ Ω

Lower limit10^-8 ΩUpper limit10¹⁶ Ω

Ohm's Law

V = I R

Resistivity

R = \dfrac{\rho l}{A}

Capacitor Discharge

Q = Q_0 e^{-t/RC}