project design

[deleted-184203]

One of the "science buddies" experiments listed on this website concerns aircraft detectability using radio waves and covers stealth technology and background. My son found this topic very interesting and would like to attempt this experiment while making a modifications for originality.
His question concerns the design of this experiment presented. The design includes measuring light wave emissions versus radio waves without giving the reader an explanation as to why. The experiment designer seemed to be making an assumption that measuring light and radio waves were of the same principle therefore making the results of the light wave data applicable to measuring radio waves.
Is this true? Can my son perform a similar experiment making this assumption? If so, why?

Thank you.
Dr. Joy Dozier

[rmarz]

jd1 - This is an interesting experiment, and although I haven't actually done it, maybe I can help explain the light vs radio wave part of it a little better. As you probably know, visible light is a very narrow part of the electromagnetic wave spectrum that can practically range from kilohertz to terahertz in frequency, so light waves and radio waves are part of the same electromagnetic spectrum. Visible light is actually at a frequency much higher than traditional radar (and much shorter wavelength). For this experiment, visible light was probably chosen because measuring instruments such as the luxmeter are much cheaper than radio wave energy measurement devices. The source, or emitter (the LED flashlight) is also much cheaper than an equivalent RF transmitting device. The added benefit is that nothing too dangerous is used here, and the experimenter can readily view the setup and see if it is working. While there might be differences in how some materials reflect the much different frequencies of RF (radio waves) and 'light', remember we are just trying to do a relative measurement experiment here as to what kind of surfaces scatter light better, thus making them more or less observable, or 'stealthy'. Attached link is to a electromagnetic spectrum chart which you might find helpful in understanding the experiment. There are many more similar charts on the web. Good luck.

Rick Marz

http://www.lbl.gov/MicroWorlds/ALSTool/ ... Spec2.html

[deleted-184203]

Thank you for the clarification and feedback, Rick. I'd assumed cost and practicality were factors in driving the design, but I wanted to be sure we weren't missing anything else. I'll have him read more about the spectrum with the link that you sent.
This forum serves a great purpose. I appreciate your help.
All the best,
Joy