I used a USB Microscope Camera from adafruit to capture this detail. Read more about light emitting diodes on wikipedia

Remember the first time you played with Light Emitting Diodes? Well today I have the privilege of sharing LEDs with Tasmeem! The wikipedia LED entry tells all. I would add a label for the P-N junction and note that typically the positive lead is the longer one.  

Charged electrons flow from the power source along the negative trace (green) thru a resistor to the cathode. Like excited lemmings they jump the P-N junction emitting light. Finally, the spent electrons slide along the positive trace (red) to get charged up at the battery.         KEY battery is black negative trace is green resistor is blue […]