Now that we know that even the mighty LED has its limits, we need to make sure we stay below those limits. Being kind to your LEDs will let them last longer and keep them shiny & bright!
Lets examine the specification sheet for a 5mm LED, specification sheets are also called datasheets. Datasheets are immensly useful, they have all the information you need for an electronic component. You can download the datasheet we'll be referring to here.
The first useful thing you'll find is the dimensional 'package' information. The 'package' here is the LED itself.
As you can see, the main diameter of the LED is 5mm (its a '5mm LED') and there's a lip that makes it around 6mm. The lip can make it handy if you're gluing the LED into a drilled hole, so it doesnt fall through. The datasheet also tells you which pin is the cathode and other lengths and sizes. Note that the figures are in mm with the inches in ()'s afterwards.
Keep scrolling down. Next you'll find this small table. This section tells you how bright the LED is in mcd. Since these are general purpose LEDs, the brightness can vary a bit, these LEDs average around 250 mcd, but the manufacturer may sell you LEDs that are as dim as 180mcd. This variation is pretty standard.
The first two rows talk about the 'wavelength' - this is a specific way of indicating the color. After all, 'super bright red' is a very subjective description. With the wavelength, we can know exactly what color is emitted.
The third row is basically saying 'how much does the color vary from the wavelength'
The forth row isnt so important, we'll skip that
The fifth row, however, is what we're looking for…