LED guide: LED terms and definitions you need to know
Color temperature, more completely Correlated Color Temperature (CCT), is a reference number for judging how warm or cold is the color of a white light source. CT is the color of light given off by a particular light source that most closely represents the light emitted from a perfect blackbody radiator when heated to a specific temperature. Incandescent bulbs are often 2700K, called a warm white light, while fluorescent lamps can have CCT’s varying from 3000K to 5000K, called a cool white light. 3500K is generally considered “neutral” white light. Today’s LED tube lights can have CCTs ranging from 2700K to 5000K. (K, or Kelvin, is used as the unit of measurement for temperature in the physical sciences. As a reference, 2700K is about 2427°C.)
Because LEDs are such an intense light source, lenses are often placed in front of them to spread the light out and these lenses are called diffusers. They often have a frosted appearance.
A basic component of electronic circuit design, diodes only allow current to flow one way. For current to flow, the diode must be positively biased, with a positive voltage on the anode side, and the negative voltage on the cathode. All diodes, including LEDs, have a forward voltage drop; Vf. Vf remains relatively constant even as the current run through it varies. (Within limits: If you run 10 amps of current through a diode rated at 100mA, the diode simply burns up.) Generic diodes are valued more for the amount of current they can carry and still withstand a reverse voltage. [Side note: Diodes have a common use in LED replacement bulbs: When arranged in a diode bridge, they block the negative half of the ac house voltage and rectify it, or turn it into a positive voltage so that it can be massaged by the LED driver into a well-behaved current source.] LEDs are special form of diode: As you run current through them, they emit light.