A diode only allows current to flow through it in one directionThis property is important in electronic circuits as some components are affected by the direction of the current.The LED or light-emitting diode emits light of a specific wavelength by transferring electrical energy directly to light energy. They use very little energy are usually used as indicators to show when a circuit is live.The potential difference is not directly proportional to the current.In one direction - the reverse bias - the resistance is very high and the diode does not conduct.In the opposite direction - the forward bias - when the p.d. reaches a threshold of about 0.7V the resistance drops sharply for a very small increase in p.d. and the diode has very little resistance.Different LEDs have different threshold values.
