All About Lights
What exactly is light intensity (cd)?
Light source in a direction of luminous flux within the solid angle size. In general, the light source to the different intensity in different directions in order to shine their luminous flux. In a specific direction of the visible light, emit radiation known as light intensity.
What is brightness (cd/m2)?
Brightness is the perception elicited by the luminance of a visual target. This is a subjective attribute/property of an object being observed.
What is luminous efficacy (lm/W)?
Luminous efficacy or lighting effect is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power or wattage. Here are some examples of luminous efficacy of different light sources:
incandescent ~ 15
fluorescent ~ 70
CFL ~ 50-80
LED light ~ 70-90
What is illuminance (lm/m2)?
Illuminance is a measure of how much luminous flux is spread over a given area. One can think of luminous flux as a measure of the total “amount” of visible light present, and the illuminance as a measure of the intensity of illumination on a surface. Its unit is lux. One lux is equal to one lumen per square metre. Here are some examples of the illuminance provided under various conditions:
Full daylight (not direct sunlight) ~ 10,000 lux
Overcast day ~ 1,000 lux
Sunrise or Sunset ~ 400 lux
Office lighting ~ 320 – 500 lux
Very dark overcast day ~ 100 lux
Office hallway / toilet lighting ~ 80 lux
Family living room lighting ~ 50 lux
What is color temperature (K)?
The color temperature of a light source is the temperature of an ideal black body radiator that radiates light of comparable hue to that of the light source. Its unit is expressed in kelvins; A higher kelvin number means the light is cooler/more blue, and a lower number means that it’s warmer/more yellow. For example, color temperature over 5300K are called cool white color or daylight color or sunlight, which is near natural light, brings you a bright feeling, and makes you vigorous. Widely used in office, meeting room, class room, drawing room, design room, laboratory, reading room and so on. The color temperature (3300-5300K) named neutral color, the color take you a happy, comfortable, serene feeling, widely applied in shop, hospital, office, restaurant, waiting room etc. Lower color temperatures (2700-3300K) are called warm white color, which is near that of incandescent light, more red, can bring people warm, healthy, comfortable, suitably applied in family, housing, dormitory, hotel and low-temperature occasion.
What is color rendering (Ra)?
In principle, artificial light and natural light should be the same, using the naked eye can correctly identify the color of things. Of course, depending on the location and purpose of lighting may be. Color rendering light source for the extent of an object as color rendering, often called the “color rendering index”
What is beam angle (half-value)?
Beam angle is the angle between direction of light intensity to reach half of normal intensity and normal direction.
Do LEDs have to warm up like other energy efficient lights?
All LEDs are “instant-on” and “instant-off.” Anyone who has used halogen lights, fluorescent lights, or the smaller CFLs (compact fluorescent lights) will be familiar with the flickering, slow powering up of these other energy efficient lights. It is a common frustration. LEDs do not have this “warming up” problem, and reach full power and luminosity in a matter of milliseconds. They also turn off without the flickering and warming down that is common
with other types of non-incandescent lighting.
Are LEDs as bright as other lights?
Comparing the brightness of LED lights such as our LED bulbs and incandescent bulbs is difficult because they consume such different amounts of electricity. An “efficient” warm white, 60W incandescent light bulb produces around 800 lumens. A comparable 60W-equivalent LED bulb that consumes 7 watts of electricity produces roughly 700 lumens. So although it produces about 12 percent less light, the LED alternative produces 6.7 times as many lumens per watt. So for a given amount of electricity consumed, LED lamps are far brighter than traditional lamps.
How do LEDs compare to CFL bulbs?
LED lights and compact fluorescent lights (CFLs) are the two most popular energy-efficient lighting options. However, the similarities end there. LED lamps are easy to install, are durable and long lasting, generate little heat, and contain no hazardous substances of any kind. CFLs, on the other hand, may require specialty fixtures, are easy to break, have a lifespan about one-fifth that of LEDs, produce a decent amount of heat, and contain dangerous mercury gas that is released when they are broken. They are also less convenient and comfortable to use because they often take a while to “warm up” and reach full brightness and often flicker and hum. Additionally, every cycle of turning a CFL on and off decreases the bulb’s lifespan. These differences mean that for a slightly higher price, LEDs provide better safety, increased savings, greater comfort, and better environmental
friendliness. Some LED lights and CFLs available at major hardware retailers have comparable energy efficiency, while in most cases LEDs are noticeably more energy-efficient. Of course, the other advantage of LED lights is that because most of them use fewer watts than CFLs.
Why are LEDs so energy efficient?
The main reason that LEDs use so much less electricity than traditional lighting is that they don’t produce light in the same way. Incandescent lights pass electricity through a filament that must get extremely hot for its atoms’ electrons to become excited enough to give off light. Most incandescent bulbs waste about 90% of the electricity they consume as heat because of this, making them incredibly inefficient light producers. LEDs, such as the popular LED recessed fixtures that easily replace incandescent fixtures, produce light using electroluminescence. This process doesn’t use a filament and creates little heat, instead relying on a property of semiconductors to generate light. It is thus far more efficient at converting electricity into light.
That efficiency is what enables LEDs to produce the same amount of light as the bulbs that LED recessed fixtures would be replacing, while consuming so little power. Of course, the fact that LEDs don’t waste energy by creating or relying on excess heat is also part of what makes them so safe, as well as why they don’t need the large, fragile glass bulbs full of toxic gasses that make handling other lighting sources more difficult.
Do LED lights screw into standard household light sockets?
Yes, LED lights are direct screw in replacements for household lights. You unscrew your incandescent light bulb and screw in your LED Light bulb. You do not need to redo your electrical system to use the LED lights.
Do LED lights generate heat?
Yes, comparing with energy saving lamp, LED lights generate very little heat. They are ideal for kitchens, dens, offices, or anywhere you are working in close proximity to a standard light bulb. That is why LED Lights are so energy efficient.
Can I use them to replace incandescent bulbs in an enclosed ceiling light fixture ?
Yes, the LED light bulb is a direct replacement for incandescent bulbs, energy saving lamp, and CFLs.