How can compact fluorescent bulbs use only 13 Watts and put out the equivalent of 60 Watts?

The first thing to understand is the construction of each type of bulb. The light from an incandescent bulb is generated by sending a lot of electricity through a tungsten filament which causes it to get white hot. A compact fluorescent (CFL) lamp however, is filled mostly with mercury gas. As electricity pulses through the mercury vapor, the energy associated with the electrons on the mercury atoms increases. Because the electricity is pulsed on and off, electrons eventually lose the extra energy, and they release the extra energy in the form of emitted light.

The key difference here is in the colors that are emitted, and to illustrate the difference I have analyzed each type of bulb with an optical spectrometer, a device which analyzes light signals and determines what "color", or wavelengths" are present. Both bulbs were analyzed within minutes of each other. Both bulbs were allowed the same amount of time (minutes) to warm up, and were analyzed at the same distance and spectrometer settings. Here is the plot showing the two types of bulbs:

The point of this graph is to show that the incandescent bulb emits light not only in the visible spectrum, but also in the infrared region that we can't see. That means that 42% of the tungsten bulbs efforts are wasted, and we haven't even talked about energy losses to the heat generated in this kind of light bulb. Considering the CFL bulb, humans can see 95% of the light that is emitted, and these bulbs generate less heat.

So, in basic terms, a tungsten bulb is wasting a lot of energy. But, tungsten bulbs still have a healthy self-esteem because they will never be as toxic to the environment as the mercury in the CFL's.

Are compact fluorescent bulbs really more efficient than traditional light bulbs?

Yes!

Really, that's the answer.

Well, this would be a boring post if there wasn't an explanation. So, here goes . . .

First off, a typical compact fluorescent lamp (CFL) designed to be equivalent to a 60 W incandescent bulb, only uses 13 W. That is an immediate 25% saving on the electricity required to power the light! But, what about the upfront purchase price? Typically, incandescent bulbs are about $0.25 each, while a CFL can be anywhere from about $1.33 at IKEA to upwards of $5 depending on where you buy it! So, then how long will it take to break even?

Let's start with an average price for the CFL, about $2.50. The incandescent is 10 times cheaper. How long will it take to break even? Using local electric utility prices ($0.07/kWh), it turns out that the break even point is about 2000 hours of use. Over that time, two traditional bulbs will be required, while the original CFL will continue to run for about 6000 more hours.

The final cost break down means that over the life of one CFL, you would have gone through about 8 tungsten bulbs, and by using the CFL, you would save about 2 dollars in electricity! Now multiply that by the total number of bulbs in your house, and that adds up to night out for dinner.

P.S. In order to save that kind of money, you would have to be a person who leaves their lights on all day and all night for an entire year, I'm just sayin' . . . .

Is that exit sign radioactive?

Adorning the exits of the church building I attend are exit signs that look generally unassuming like this:

However, you may note that there are no wires or conduit leaving this lighted sign. How is it lighting up then? It turns out if you look underneath the sign, you see a label that looks like the picture below. It is radioactive!

But, don't worry, this exit sign is not the reason you feel warm and fuzzy when you leave the building. In fact, the sign is designed so that no radiation should leave the tubes holding the radioactive material, tritium. Tritium emits one kind of radioactive particle, beta particles, which are contained within the tubes that hold the tritium, and nothing else. The insides of these tubes are lined with a phosphorescent material. When the radioactive particles collide with the phosphor, green light is emitted!

This type of sign is only good for a about 10-15 years. During that time, no electricity is required, and everything will be fine as long as no one knocks the sign off and it crashed down and releases all the radioactive tritium gas.

Are rainbows reflecting polarized light?

This question came to me (6/13/2009) while looking at a rainbow out my back porch. Rainbows frequently appear behind my house (east) when it is raining in the evening. I was thinking about how the light is reflected inside the raindrops when I remembered that reflected light tends to be polarized. This is why polarized sunglasses work so well. For a fishing example, see: http://bit.ly/gS1x9E. I held my polarized sunglasses in front of my camera and rotated the glasses back and forth. I apologize for the low quality, I was more worried about recording the phenomenon at the time, and didn't check the settings. his was a fun discovery!

How can people handle fire and not be burned?

Someone recently asked me about how people can handle fire. My first thought was about a chemistry demonstration called "the burning dollar," where a dollar is soaked in a 50:50 mix of water and rubbing alcohol. When a match is set to the dollar, the alcohol ignites and dollar appears to be on fire. But the water in the dollar prevents it from burning, at least for a little while (avoid ever trying this out with a $20 - and uh, no, this recommendation doesn't come from experience). They referred to a YouTube video where someone used a small piece of rag rolled up and held together with a rubber band to form a small ball. It was then soaked in some kind of fuel, and by continually moving the ball between hands, handling the burning ball was possible.

Using this technique, it is relatively easy to handle fire; and by easy, I mean that I only got a few first degree burns in the process of trying to do it. Additionally, when there is too much fuel, it drips out of the ball and onto other surfaces, subsequently lighting them on fire. Also note that in the following video, the ball is soaked with a little too much fuel, and it leaked onto my fingers (OUCH!). As a result, I give this one the "Don't try this at home" status, or, "Just watch the video instead," advice. I also found a few videos of people (whose sanity should be checked) trying to breathe fire, with disastrous results I should add. Is there a slogan somewhere that says something about only you can prevent a forest fire on your face?