Science Buddies: "Ask an Expert"

I am testing to see which form of lightbulbs is the most cost effiecent ( LED's, CFL's and Incandescent's ). I have my project set up with a three socket extension cord in which each socket attachs to the lightbulb. I don't know how to attach an electrict meter to each lightbulb in order to measure each bulbs energy usage. If anyone knows how to do so please respond ASAP because my teacher announced yesterday that the procedure would be due on Monday.

Thank You

Hello and welcome to the forum:

I would suggest using a meter such as the "Kill A Watt" http://www.google.com/products/catalog? ... CHoQ8wIwAQ

You will need to measure the bulbs one at a time.

Keith

How are you planning to measure the light intensity?

Take for example a two filament "Three Way" tungsten bulb 50/100/150w. It is straight forward to demonstrate that at 50w, less light is produced than at 100w, and 150w produces the most light. The same can't be said for comparing a 19w CFL bulb to a 25w tugsten bulb.

If you are powering all your bulbs under test from the same voltage power source, you should be able to simply use the manufacturer's wattage rating and not have to measure the power consumed as long as there is no other circuitry such as a balast involved. You probably can't just use any manufacturer's data on how many lumens a bulb produces. For most CFL bulbs, the temperature has a huge effect on the light output. For fluorescent bulbs, the balast has a large effect on the efficiency. Many light bulbs have highly directional light intensity patterns so the light fixture and the surroundings have a big effect on how useful the light output is.