Photosynthesis Experiment - Do LED's work?

[mshort]

Hi,

Does anyone know if using a battery powered LED light instead of an ordinary 40W bulb will work as well for a standard photosynthesis rate experiment? (we currently use a short section of Elodea in water and a lamp).

Thanks

[JackBean]

depends on wavelength of your LED

[jonmoulton]

Try a red and a blue LED in combination.

This would be an interesting experiment to try: compare 2 red LED sources, 2 blue LED sources versus 1 red and 1 blue source in combination.

[mith]

Just remember the LED is a diode so you need to control the current running thru the circuit. Put in a limiting resistor or you will possibly damage it.

[jonmoulton]

A Buck Puck is a nice device for limiting current to an LED.

[Vaucheria]

LED lamps work, and they are pretty eco if you ask me (they use less power). But as guys before me said, you need the right colors.
Here is my handmade LED lamp:


The "white" ones on the photo are actually blue. I think maybe more blue lights would work better than the ratio I have here, but the blue ones are very expensive here and my plants were fine with this.

It's a bit ugly but it does the job:) And it costed me less then 15 euros to make (the most expensive part was the voltage adjusting device).
And I did a little laic experiment when I made it, I've planted 2 leeks at the same time (same soil) and kept them apart but made sure that they were on same temperature and humidity. One was growing under sunlight and the other one was kept without ANY exposure to natural light, in a locker with only LED lamp lighting it.
Here are the results:


The left one was kept under LED lamp and the right one was kept on the sunlight.
This was only to see for myself that the plant could survive living under LED (leeks are pretty easy to nurture so I don't give much credit to it).

Anyways, my current plants all do very well under the LED lights (I don't have any sunlight in my room so I use it as a main source of light for them) and I guess It's worth a try
The common red and blue LEDs sold here have the desired light wavelength for plants...

[JackBean]

or you can try christmas lights, that should be cheap