Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: radio waves?  (Read 646 times)
KC0IMF
Member

Posts: 10




Ignore
« on: January 06, 2001, 10:03:46 PM »

my dad asked me a strange question today. he asked wich traveled faster radio waves or light waves.I personally think light waves do by a large margin. but like all humans i could be wrong if you have any data that may help exsplain this to him easier then please let me know
Logged
N6QTH
Member

Posts: 42




Ignore
« Reply #1 on: January 06, 2001, 10:58:47 PM »

I believe the best way to answer your question is to recommend you read the information on this single web page:

http://www.scitoys.com/scitoys/scitoys/radio/homemade_radio.html

Logged
VK2GWK
Member

Posts: 196


WWW

Ignore
« Reply #2 on: January 07, 2001, 05:19:14 AM »

Instead of inviting your Dad to build a crystal radio - as the previous Elmer suggested - it may be simpler to tell him that radio waves and light waves are the same..... Light is a radio wave with a very short wave length (thousands of a millimeter - or over ten thousands of an inch if this feels better for people that still did not accept the decimal system).
So... radio waves and light waves have the same speed.
(I wonder what the curriculum in US schools is these days).
Logged
N2MG
Administrator

Posts: 0



« Reply #3 on: January 08, 2001, 11:47:25 AM »

Light waves and radio waves are both electromagnetic waves and they travel at the same speed, c (297,000,000 meters/second), in a vacuum, somewhat slower in air, and significantly slower in cables.

One uses the velocity factor (typically .66-.80) of coax to determine the true speed of RF in the cable (e.g., for coax w/ 0.80 velocity factor, radio waves travel at 0.8 * c).  The Index of Refraction (IOR, one standard being 1.476) is a similar factor for fiber optic cable where (1/IOR) * c is the speed of light in the fiber.  Notice that using these two cables, RF in the coax travels faster than light in the fiber.

Several years ago, a front page article in the Wall Street Journal was extolling the virtues of fiber optic-based communications and credited the "fact" that light travels so much faster than radio waves, and this was the primary technical reason for using fiber.  Sigh.
Logged
WB6BYU
Member

Posts: 13567




Ignore
« Reply #4 on: January 08, 2001, 01:58:35 PM »

Actually,  I should stand up and defend our system of measurement!
Ten-thousands of an inch is, indeed, a decimal system.  Otherwise
we would use 2.4 / 64 / 64's of an inch!

(Actually, the US has officially adopted the metric system - in fact,
it was before 1900.  However, they have allowed the use of
common units of measurement in the interim...)

At any rate, light and radio waves are both electromagnetic
waves, which travel at essentially the same rate, whether it is
measured in meters per second, miles per hour, or furlongs per
fortnight.
Logged
N6QTH
Member

Posts: 42




Ignore
« Reply #5 on: January 09, 2001, 12:11:40 AM »

Toby,
I recommended you read the web page covering crystal radio construction for two reasons:

1.  The answer to your question is incuded in that information on that page.

2.  As a teacher, I find that students who are shown where to find an answer usually accomplish more than simply satisfying a curiosity.

I suspect you will want to advance beyond Technician.  While it is true that you can advance your license status using purely rote processes for test taking, you may find it more satisfying if you're completely confident with your own ability to independently prove your answers to various technical questions.
I hope you will read that web page.
 
Logged
KC0IMF
Member

Posts: 10




Ignore
« Reply #6 on: January 09, 2001, 11:47:49 AM »

thank you all for the answers and yes i do plan to advance past tech liscense. I thank you for the web site and plan to try the projects and the reading on it.I love to learn new things and see why and how things work.So if you have more like that one feel free to send them to me via e-mail at kc0imf@yahoo.com agian thank all of you for your help.
Logged
RobertKoernerExAE7G
Member

Posts: 1435




Ignore
« Reply #7 on: January 18, 2001, 03:46:31 AM »

I've always thought it was pretty fascinating that the emission of an electron, a photon, or light, travels at the same speed as the radio waves we generate with our antennas.
I may have been taught that in HS, but I don't remember it fom there; but rather, from being curious, and reading science magazines for many years after HS and college.
I think what got me fascinated with radio waves, was, as a small child, building a crystal radio kit that pulled radio out of the night sky, without being plugged into electricity -- pure magic!  Every body knew that radios only worked when you plugged them in and turned them on!
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!