LEDs

LED’ stands for Light Emitting Diode, a circuit component that emits light. The symbol for an LED is displayed below:

A diode is a special kind of component that only permits current to flow through it in one direction. To achieve this it has very low resistance in one direction to allow current flow and high resistance in the other direction to impede current flow. This feature of diodes is clearly represented in the generic diode circuit symbol:

An LED diode lights up when the right amount of current flows through it. A standard LED has a maximum current of 20mA. An appropriate resistor must therefore be added to the circuit to ensure the current doesn’t exceed this amount.