LED lamp is an electric light or light bulb for use in light fixtures that produces light using light-emitting diodes (LEDs). LED lamps have a lifespan and electrical efficiency which are several times greater than incandescent lamps, and are significantly more efficient than most fluorescent lamps,[1][2][3] with some chips able to emit more than 300 lumens per watt (as claimed by Cree and some other LED manufacturers).[4] The LED lamp market is projected to grow by more than twelve-fold over the next decade, from $2 billion in the beginning of 2014 to $25 billion in 2023, a compound annual growth rate (CAGR) of 25%.[5] As of 2016, LEDs use only about 10% of the energy an incandescent lamp requires.[6]
Like incandescent lamps and unlike most fluorescent lamps (e.g. tubes and compact fluorescent lamps or CFLs), LEDs come to full brightness without need for a warm-up time; the life of fluorescent lighting is also reduced by frequent switching on and off.[7] The initial cost of LED is usually higher. Degradation of LED dye and packaging materials reduces light output to some extent over time.
Some LED lamps are made to be a directly compatible drop-in replacement for incandescent or fluorescent lamps. An LED lamp packaging may show the lumen output, power consumption in watts, color temperature in kelvins or description (e.g. “warm white”), operating temperature range, and sometimes the equivalent wattage of an incandescent lamp of similar luminous output.
Most LEDs do not emit light in all directions, and their directional characteristics affect the design of lamps, although omnidirectional lamps which radiate light over a 360° angle are becoming more common. The light output of single LED is less than that of incandescent and compact fluorescent lamps; in most applications multiple LEDs are used to form a lamp, although high-power versions (see below) are becoming available.
LEDs, as their name suggests operate as diodes, and run on DC, whereas mains current is AC and usually at much higher voltage than the LED can accept. Although low voltage LED lamps are available LED lamps can contain a circuit for converting the mains AC into DC at the correct voltage. These circuits contain rectifiers, capacitors and may have other active electronic components, which may or may not permit the lamp to be dimmed.