> I think the term used for the SI is "coherent," ie 1 x 1 = 1, none of your > dynes, cubits, foot-pounds etc. A pity our cousins from across the water > are not all on board the SI express. > > David > G3UNA > > > > On 12/8/2008 9:49 AM, Barry Garratt wrote: > > > >> Actually a radian is an angular measurement whereas a Hertz (hertz) is a > >> frequency measurement. > >> > >> 1 radian = 57.2958 degrees > >> > >> 1 hertz = 1 cycle per second
etc. One problem is that "cycles" are not really units, [nor are radians]. That is to say they don't HAVE units. They are non-dimensional. F'rinstance, look at the relationship between the speed of light, wavelength, and frequency: c = lf [I prefer "lambda" for l, and "nu" for f, but my e-mail client won't type those very easily] c = speed of light in meters [or metres] per second l = wavelength in meters f = frequency in ???? Well, it has to be inverse seconds [sec^-1] for things to work out. There aren't any "cycles" or "radians" in that frequency figure. We physics types often use "angular frequency" instead of "frequency". We just multiply f by 2pi to get angular freqency. [It's still in inverse seconds.] Why would anyone want to do that? Look at your formulas for capacitive and inductive reactance for hints. That's why it's silly to have defined the Hertz as the inverse second. What's even sillier is having defined inverse Ohms as Mhos. I don't believe there ever was a Mr. Mho. [Mho Nomis Groeg??] Radio is sure fun! vy 73, George T Daughters, K6GT CU in the California QSO Party (CQP) October 3-4, 2009 _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
