# Resistor

Resistors are used to change the amount of current flowing through a part of the circuit. This is often used as a means of protecting components which cannot handle large currents.

The current allowed to flow through a resistor can be calculated using: I = V/R (current = voltage/resistance).

There are many different resistors available, so they have a sequence of coloured stripes to show their resistance. See here for details on how to decipher the colour coding.

## PURCHASE

Resistors can be purchased from most electronics retailers.

For the purposes of these tutorials, any wattage rating is sufficient. If you later intend to use the resistor in higher-power circuits, you will need to ensure that the wattage is at least as large as the resistance multiplied by the current squared (P = I^{2}R).