radio waves

[playgirl]

what is the minimum length that a long wave radio wave can be?

[jake-the-peg]

Nasa says 10 micrometers.

http://weather.msfc.nasa.gov/irgrp/defs.html

[playgirl]

thanks jake.

[Loosehead]

Jake, that link referes to the infrared portion of the spectrum. Long wave lengths can be up to 1000km. see here:

http://dspace.dial.pipex.com/town/pipexdsl/r/arar93/mds975/Content/radtech.html

The wave length is a function of frequency, the term long, medium and short wave are agreed frequency conventions across the spectrum note that the shortest long wave is a lot longer than the longest medium wave so there are gaps in the terminology, not the frequencies. Long wave is from 148.5 to 283.5 approximately 600km - 300km

[jake-the-peg]

Whoops you're right  - bit of Friday afternoon creeping in there! 

[playgirl]

i've got the correct answer,and it's 1000 metres. thankyou both for your help.