[geocentrism] Re: modern edu

  • From: "philip madsen" <pma15027@xxxxxxxxxxxxxx>
  • To: <geocentrism@xxxxxxxxxxxxx>
  • Date: Thu, 27 Sep 2007 08:07:51 +1000

Philip M 
It might be considered unconventional, but in the second line of the solution, 
the 'u' (mu) substitutes adequately for the 10^-6. Their answer is correct.
Paul D

It is unconventional and inadequate for me. In my school, symbols were in the 
formula, which indicated capacitance as C  and the basic unit is farad. Unit 
titles are excluded from the formula but explained in a following line. eg

Xc = 1/ 2piFC   where F is in hertz and C is in farads etc etc. . 

During substitution, one never wrote in the unit titles such as Hz or mf.. ( 
except as an aid) Following convention the quantity 50mf must be converted to C 
in Farads before being put in the denominator as a number. 

Thus,  C should be substituted as 50 x 10^-6  not 50mf. As a teacher I would 
not allow the placement of 5 x 10^-5 shortcut till I knew the kid knew what he 
was doing and why. 

Hence again on the next line of calculation 10^-5 is transferred to the 
numerator above the line as 10^5. and the final substitution looks like this 

10^6 / 6.28 x 100 x 50

=100000 / 3140   


So they get  the answer correct,  but this is bad teaching method, like you 
said unconventional.  u or mu is not always "micro" in technical terminology. 
see below. 

My text books  for convenience converts the formula to suit the more practical 
unit microfarad, to 

Xc  =  10^6  /  2 pi x f x C  where C is in microfarads.  Likewise for Henrys 
in inductance. 

Methinks the calculator has ruined young minds... Well ye all know I think 
that..  But such confusion did cause that expensive crash on Mars..  If they 
had Jules Vernes machine and recruited a team from Britain 1940, that mistake 
would not have happened... no ways, nor a lot of other mistakes. 


Mu can be:

  a.. Mu (letter), M or ?, a letter in the Greek alphabet pronounced "mew" 
(/mju/). ? is used as a symbol for: 
    a.. The SI prefix micro, denoting a factor of 10?6 (one millionth). 
      a.. ? by itself is often used as the "unit" of strain, though in this 
context it retains its SI prefix meaning, which is interchangeable with "x 
10?6" or "ppm" (parts per million). 
      b.. ? by itself is a deprecated abbreviation for the deprecated unit 
micron. The preferred terms are µm and micrometre 
    b.. In mathematics, 
      a.. The arithmetic mean of a statistical population 
      b.. The Möbius function 
      c.. The least-fixed-point-operator 
      d.. A degree of membership from a fuzzy set. 
    c.. In chemistry, 
      a.. The chemical potential 
    d.. In physics, 
      a.. The friction coefficient 
      b.. The mobility coefficient 
      c.. The permeability (electromagnetism) coefficient 
      d.. The muon, an elementary particle 
      e.. The standard gravitational parameter 
      f.. The magnetic dipole moment 
      g.. The linear density 
      h.. Viscosity 
      i.. Reduced mass 
    e.. µTorrent, a freeware BitTorrent client for Microsoft Windows written in 
    f.. ?Ziq, An alias of Mike Paradinas. 
  ----- Original Message ----- 
  From: Paul Deema 
  To: geocentrism@xxxxxxxxxxxxx 
  Sent: Thursday, September 27, 2007 1:39 AM
  Subject: [geocentrism] Re: modern edu

  Philip M 
  It might be considered unconventional, but in the second line of the 
solution, the 'u' (mu) substitutes adequately for the 10^-6. Their answer is 
  Paul D

  ----- Original Message ----
  From: philip madsen <pma15027@xxxxxxxxxxxxxx>
  To: geocentrism@xxxxxxxxxxxxx
  Sent: Wednesday, 26 September, 2007 5:04:18 AM
  Subject: [geocentrism] modern edu

  Please tell me I aint nuts. I don't use formula often, so though I 
instinctively say reactance is I forget the application for microfarads when 
the unit is Farad in this equation. 

  Yet just look how this formula is applied in not one but two different 
websites..  . Note they correctly state for this formula, C is capacitance in 
farads yet substitute microfarads into the equation. Isn't their answer wrong.  
shouldn't there be a 10^6 on the top line. 

  50 micro Farads = 50 x 10 to the -6th. Farads. 

  Or am I just too old and missing something. Can a math man please check me 
out? I compute the answer should be 31,250 ohms.    Philip. 


  Now you can understand why it is said that the XC varies inversely with the 
product of the frequency and capacitance. The formula is: 

  Where: XC is capacitive reactance in ohms,  f is frequency in Hertz, C is 
capacitance in farads, p is 6.28 (2 X 3.1416) The following example problem 
illustrates the computation of X C. 

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8:02 AM

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