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Ohm's law

Current is charge per time, voltage is energy per charge, and resistance is a component's opposition to the current. Ohm's law links these three: doubling the voltage across a given resistance doubles the current. The law holds for most common components such as wires and resistors.

U = RI

Ohm's law

I = \dfrac{Q}{t}

current, charge per time

Symbols

$U$	voltage	V
$I$	current	A
$R$	resistance	$\Omega$

Example

A 12 V battery is connected to a resistance $R = 8.0$ Ω. The current becomes $I = U/R = 12/8.0 = 1.5$ A.

Convert mA and kΩ to A and Ω before calculating, or remember that mA times kΩ actually gives volts directly.

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Part of Foundations of Physics: Electricity.