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

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## Kirchhoff's current law[edit | edit source]

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

## Kirchhoff's voltage law[edit | edit source]

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

## Ohm's law[edit | edit source]

```
The voltage across a resistor is equal to the product of the resistance and the current flowing through it.
```

## Watt's law[edit | edit source]

```
The power across a resistor is equal to the product of the voltage and the current flowing through it.
```