Re: Young's Interference, on the cheap

Harry,

I forgot to mention where you could see a picture of my iron ring:
http://www.flashevap.com/ironring082605.jpg

Bob



hhc314@xxxxxxxxx wrote:
Bob, then you are an "old fart" like myself. :-)

Actually, you're not quite that old, since the first edition of
Halliday and Resnick was copyrighted in 1970, while Sears and Zemansky
dates back to 1949. Still, both are excellent introductions to physics
for the serious student.

On a plus note, you've inspired me to visit Radio Shack and pick up one
of those laser pointers to play with. My only laser currently is a
surplus assembly from an early supermarket scanner that will eventually
either electrocute me or zap out my eyeballs! (In my case, having
cataract lens replacements in both eyes, I need to be a little
cautious. Too much neutron flux in my earlier years...I guess.)

Harry C.




Front Office wrote:

hhc314@xxxxxxxxx wrote:

Sorcerer, actually I should have steered him to a textbook explaing
Young's Experiment rather than some simplist web crap.

A little late, but here are two:

"Fundamentals of Physics", Halliday & Resnick. Page 784.

Good ol' Halliday & Resnick. I've had both volumes for over
40 years now. I consult them often -- so often the cover has
fallen off Volume II, the one with page 784. Wonderful set
of books.

Bob




"University Physics", Sears & Zemansky. Page 836.

One or both of these are available at most libraries (college and
public). Both are written at the level of Physics 101, and should be
quite readable for any highschool student. In this case no knowledge of
calculus is even required, although a basic working ability in algebra
of trigonometry will help to comprehend the idea.

The important concept here is to understand the Young's Experiment
requires two separate the phase consistent beams. Coherent laser
radiation is not required to perform the experiment, although it makes
it far easier. If you don't understand how these two beams are created,
or the difference between diffraction pattern and interferrence
pattern, you need to refer to a textbook, not the web.

Harry C.






Sorcerer wrote:


<hhc314@xxxxxxxxx> wrote in message
news:1163558688.210428.145010@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
| What did you use for the beam splitter? Young used two slits, and the
| article that you cited employed a card. You did use something to split
| the beam, right, since a pinhole will not do that.
|
| The pinhole alone will give you a diffraction pattern, not an
| interferrence pattern as in Young's Experiment. While both
| interferrence and diffraction are both consequences of the wave nature
| of light, they are quite different effects. Please take time to learn
| the difference, else an error of this type can cost you dearly on an
| advanced college placement exam.
|
| For a simple sanity check, when you replicate the two beam experiment,
| make some simple measurements and compute the observed wavelength. Then
| compare your result with that published for your laser pointer.
| Physicists and engineers refer to this as a sanity check, without which
| you don't know what you are observing or its experimental validity.
|
| Realize that I am trying to be helpful, not critical.
|
| Good luck and kindest regards, Harry C.

About as much help as a tit on a bull.
You could at the very least have steered him to one of these
http://www.google.co.uk/search?hl=en&q=diffraction+grating&btnG=Google+Search&meta=||| Front Office wrote:| > I think I might have succeeded, on the cheap, in doing| > Thomas Young's demonstration of the wave nature of| > light. Photos are at:| >| > http://www.flashevap.com/Young.jpg| >| > I used a Radio Shack laser pointer and a piece of brass| > shim stock with a pinhole in it and a 0.005-inch diameter| > wire in front of the pinhole.| >| > I projected the pinhole light about two meters across| > my office and onto the wall, where I took photos of| > what might be interference of the red light.| >| > The version of the experiment I am copying is shown| > at the site of the Cavendish Laboratory:| >| > http://www.cavendishscience.org/phys/tyoung/tyoung.htm|



.

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