# Kirchoff's laws

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**Kirchoff's Laws** are a set of two laws which enable one to analyse arbitrary circuits.

- First law or Junction Rule
- For a given junction or node in a circuit, the sum of the currents entering equals the sum of the currents leaving. This law is a statement of charge conservation.

- Second law or Voltage Rule
- The algebraic sum of the potentials in a closed path is zero.

In algebraic sum, we take a rise in potential as positive and fall in potential as negative. This implies that:

- If we pass through a resistor in the direction of current, the change in potential is
**-iR**. If we pass through the resistor opposite to the current, the change in potential is**+iR**. - If we pass through the cell in the direction of
*emf*(i.e. from negative terminal to positive terminal), the change in potential is +*E*. The change in potential is -*E*, if we go from the positive to negative terminal (i.e. opposite to*emf*).