LEDs or Light Emitting Diodes are small lights that come in many different colours and sizes.  They even emit infra-red and ultra-violet light.

LEDs are used in car lights, traffic signals, holiday lights, televisions and indicators to show something is switched on or off.\

More importantly, they have begun to be used as replacements for household lights for a number of reasons:

  • Unlike CFL lights, they have no toxic chemicals or mercury
  • They are very low power
  • They last for 20 years or more
  • They can be the same colour as incandescent light bulbs (CFLs cannot get the same colour match)
  • They take up less room, weigh less and thus cost less to transport


As a comparison:

 LED Light BulbCFL Light BulbIncandescent Light Bulb
Cost to run$32 / year$80 / year$330 / year
DangerousNoContains MercuryNo
Works in Cold TemperaturesYesNoYes
Turns on instantlyYesNo - has to warm upYes
Environmentally friendlyYesNoNo


The long leg of the LED is called the anode or positive leg.

The short leg near the flat spot on the case is called the cathode or negative leg.