Chapter 3 LED Lights Flashcards
What is a LED????????
LEDs differ from HID lamps in that they use a ___________ ____________to produce light instead of creating light from hot, glowing gas plasma.
LED is an acronym for light emitting diode.
Semiconductor diode
When an _______________________is passed through an LED, a tiny chunk of material at the center of the emitter called a “_______”glows a particular color depending on the material it’s made from.
ELECTRIC CURRENT
DIE
The die sits in a reflective cup to direct the light outward through an affixed ______________lens, and then the entire thing is enclosed in an ________________case.
EPOXY
EPOXY
A grow light made with LEDs consists of 5 components: \_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_
Emitters Heat Sink Drivers Cooling Fans Housing
Individual emitters are connected to the ________________, which along with cooling fans disperses the __________the LEDs generate.
Heat Sink
Heat
The light’s driver, analogous to a _______________ in HID lighting, provides _____________to the emitters
Ballast
Power
In newer-generation LED grow lights, the emitters are topped with ___________ ____________ to focus and intensify their light.
With LEDs we can control the exact __________________of light that reach our plants instead of adapting our gardening methods to what’s available. We can create plant-specific lights that are efficient for growing a particular crop.
Secondary optics
Wavelengths
3 key “stand-out qualities of LED grow lights:
________________
________________
________________
Less Heat
New Spectra Not Available Under HID
“Tunable” Lights
LED grow lights produce ___________heat than HIDs.
What happens when the light is switched off? The photons of light _____________________but what happens to them?
Less
Cease to exist
Physics tells us that photons “___________” into the “system,” which in this case is the grow room. This phenomenon is described in the theory of ______________________which states that energy cannot be created or destroyed—it can only be converted form one form to another.
This is a long way of saying that when light decays, it ultimately becomes ___________________.
Decay
Conservation of energy
Heat
1 watt of electricity equals ______________________of heat.
This is completely true for all light sources—HID lamp, fluorescent light, LED, or any other light source.
3.412 British Thermal Units (BTU).
Why do LEDs produce less heat? It’s simple: with LED grow lights, most gardeners use ________________ —somewhere between 50% to 60% of HID _____________. Less __________equals less heat.
Less watts
watts.
watts.
Infrared heaters work by heating ______________________which in turn heat the surrounding air. This is the opposite of traditional heaters where they heat the air then the air warms the surfaces. Keep in mind that in your garden, those surfaces being heated are your plants’ leaves and stems!
exposed surfaces
An additional reason LEDs produce less heat is that HID lamps, especially HPS lamps, produce a lot of waste heat in the _______________________of the light spectrum.
infrared (IR) region
If lamp manufacturers published ________________________charts that went beyond the typical end point of _______________, it would be easier to understand where this extra IR heat energy comes from.
SPD charts that go up to at least________________ would provide a way to compare some of the heat generated by different light sources.
spectral power distribution
750nm
900nm
chart below shows that HPS lights generate large peaks around ________________which is all IR heat—quite a lot, in fact, compared to the PAR light emitted.
810nm-plus,
best things about LED grow lights is the ability to control the _____________________your plants receive.
Want more blue? If your light allows it, add more blue emitters. If not, supplement with an all-blue LED fixture. If you want more red, add it. Many LED grow light manufacturers will accept special orders for grow lights with custom spectrum colors.
specific light energy
“Tunable” Lights:
Some LED grow lights offer a ____________________which allow all of the reds or blues to be turned up or down together on separate knobs.
Some growers believe that turning down the reds shortens the ___________________distance on plants—the vertical stem height between the flower or leaf sites.
Tunable spectrum
Internodal
For years, gardening “best practices” have held that internodal distances are best kept short by placing the light at the proper height and not making the plants “_____________”for a light that is positioned too high.
This holds true for LED grow lights.
Reach
These multi-adjustable lights will help unlock the spectrum secrets of many plants and will likely lead to the development of __________________ LED grow lights.
plant-or strain-specific
LED grow lights are typically positioned within _______________above the plants, while HID lamps are 18 to 36 inches above plants, saving another 12 to 18 inches.
6 to 18 inches
Rblue, and green are the primary colors of light;
Red, blue, and green
