LED Bulbs: Characteristics And Features

Light Emitting Diode (LED) and Compact Fluorescent Light (CFL) bulbs, in the recent past, pushed out traditional incandescent bulbs from the shops, homes and work places. The efficiency in lighting and savings in electricity costs have been two major factors that influenced the change. Now, with more innovations that have taken place in the field of lighting, LED bulbs are emerging as more dependable and eco-friendly alternative to CFL bulbs. 


LED Bulb 4

LED bulbs: An introduction

LED stands for Light Emitting Diode. It is a semiconductor device that generates light when electrical current travels through the device. The strength of light produced by a single LED is meager and hence multiple devises are to be used for practical purposes.  A proper design of LED bulbs ensures durable and efficient lighting. These bulbs emit light with colors of red, green, blue or amber. LED bulbs do not generate white color. To generate white light, different color LEDs are mixed or a phosphor material cover, capable of changing the color to white is used.   

Since LEDs are small in size, they offer better designing opportunities. Whatever be the chosen design, LED bulbs perform better than traditional bulbs. 

LED bulbs: Why better efficiency?

Incandescent and CFL bulbs emit light and heat in all directions. But LEDs emit light in a specific direction. It is easy to use this directional light more effectively in various applications. But, better engineering is needed to make LEDs emit light uniformly in all directions. One of the conditions stipulated for getting energy star for LED bulbs is that they should be able to discharge light uniformly in all directions. 

LED bulbs: Special characteristics

LED bulbs and useful life: LEDs normally do not burn out or fail, but the strength of light produced decreases over a period of time. This feature is called lumen depreciation.  The life time of LED product is decided based on the duration by which the strength of light decreases over 30% of its original strength.

LED bulbs require direct current: LED lighting work on direct current (DC) sources. Whenever used in alternate current (AC) sources, special circuits are required to convert AC current to DC current. 

LED bulbs and heat: The heat generated in LED lights must be drawn out from the LEDs.  In normal lights, heat generated is radiated. But, in LED bulbs, a heat sink is used to absorb the heat generated and radiate to surroundings.

LED bulbs do not require warm up time: LED bulbs reach full brightness without any time delay unlike in the case of most fluorescent bulbs. But the strength of light output of single LED light is less compared to other types of lightings and hence multiple LEDs are used together to form LED lightings. 

LED lightings: Comparison with incandescent and CFLs. 






Yellowish hue


Wide range varying from purple to red and a spectrum of white color.





Energy usage


Less (75% less than incandescent bulbs)


Power cost




Purchase cost




Life time


6 times more than incandescent

Longer, 30 times longer than incandescent and 5 times more than CFLs. Lasts for more than 15 years.

Eco friendliness

Eco friendly

Negative impact because of the presence of toxic mercury

Eco friendly

Conversion to light

10% of electricity only is converted to light and 90% becomes heat and waste.


Heat emission is negligible.

Quickness of light emission


Require warm up time


Dimming capability

Not available

Not available



LEd Bulb 2


LED bulbs: Points to be remembered during selection. 

Lumens: We are accustomed to looking for watts while selecting incandescent or CFL lamps. There is a direct relation between the brightness and watts.  In the case of LED bulbs, the parameter is lumens. The lumen (lm) is a measure of brightness provided by a light bulb. 

Here is an easy chart for reference




1600 lm



1100 lm

75 W


800 lm

60 W

8-12 W

450 lm

40 W

6-9 W

An incandescent draws 4 to 5 times more power compared to LED bulb for same brightness. LED bulbs thus become savers  of energy and power cost. 

Color: The light produced by incandescent has a yellowish hue. LED bulbs produce wide range of colors from purple to red and wide spectrum of white. Popular LED white shades are ‘warm white’, ‘soft white’ and ‘bright white’. Bright white is closer to day light, while the other two have yellow hue.  
Kelvin: Light color is measured in kelvin. Higher kelvin number indicates better closeness to day light. The light with yellow hue from incandescent is around 3000 K 

Dimming: LED bulbs can be made dimmable either with traditional dimmers or with a leading-edge (LED-compatible) dimmer.

Heat dissipation: LED bulbs too produce heat, but it does not radiate heat. If the heat generated is not drawn away, it will affect the life of the bulb. In order to have a longer life, the heat sink in the base of the bulb should be very efficient. 

Initial investment: Initial investment for an LED bulb is much higher compared to incandescent. This is recovered by its cost effective performance for a longer period. 


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