Yellow 2 Pin 5mm LED Round Light Emitting - Pack of 10

A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. The series is specially designed for applications requiring higher brightness.

The "millimeter" size refers to the diameter of the LED. For example, if you need to drill a hole in a box for your 5mm blinky LED, the hole size should be 5mm, and you'd need a 5mm drill bit to make it. 5mm is the most common size you'll see, and they can be extremely bright!

These low-current LEDs are suitable for all projects but remember the current limiting resistor. When hooking up an LED, you are always supposed to use a current-limiting resistor to protect the LED from the full voltage. If you hook the LED up directly to the 5 volts without a resistor, the LED will be over-driven, it will be very bright for a while, and then it will burn out.

Typically the LED voltage will depend on the color of the LED, being approximately 3.2 volts for cool colors such as white, blue, and green; and 2.2 volts for warmer colors such as red, orange, and yellow.

One wire is the anode (positive-long leg) and another is the cathode (negative-short leg). The two wires have different names because LEDs only work in one direction and we need to keep track of which pin is which. One goes to the positive voltage and the other goes to the negative voltage.