How to Use LED

LED is stands for light emitting diode .light make great indicator lights.they use very little electricity and they pretty much last forever.

In this lesson.you will use perhaps the most common of all LED s,a 5 mm red led.5 mm refers to the diameter of the LED.Other common sizes are 3 mm and 10 mm.you cannot directly connect an LED to a battery or voltage source because .

1.the LED has a positive and a negative lead and will not light if places the wrong way and

2.an LED must be used with a resistor to limit or 'choke ' the amount of current flowing through it otherwise , it will burn out!

if you do not use a resistor with and LED,then it may well be destroyed almost immediately, as too much current will flow through,heating it and destroying the 'junction' where the light is produced

There are two ways to tell which is the positive lead of the LED and which the negative.

Firstly , the positive lead is longer.

Secondly ,where the negative lead enters the body of the LE, there is a flat edge to the case of the LE.

If you happen to have an LED that has flat side next to the longer lead ,you should assume that the longer lead is positive.

1.Arduino UNO

2.LED

3.Resistor

4.jumper wires

connect the resistor to the positive side of the LED and negative site to ground.