# Fundamental Physics/Electricity/Electric circuits/Electric circuit laws

## Kirchhoff's current law

The sum of all currents entering a node is equal to the sum of all currents leaving the node.

## Kirchhoff's voltage law

The directed sum of the electrical potential differences around a loop must be zero.

## Ohm's law

The voltage across a resistor is equal to the product of the resistance and the current flowing through it.
${\displaystyle V=IR}$

## Watt's law

The power across a resistor is equal to the product of the voltage and the current flowing through it.
${\displaystyle P=IV}$