Quick question, what does the size of an LED do? For example like the 10mm and the 5mm and the 3mm. Ive been trying to find an answer and i cant.

 

Typically the size of the LED has nothing to do with the electrical parameters of the LED.

hgmjr

 

does it affect brightness?

 

The brightness is more a function of the amount of the current that is established in the LED within the limits for which the LED was designed.

hgmjr

 

It also has to do with visual appearance of the project. For example, if you were making traffic lights it might be better to have a larger bulb size, such as the 10mm.

 

Hello,

Here is a lot of information on LEDS.
http://www.educypedia.be/electronics/composemiconductorsled.htm

Greeting,
Bertus