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A question of units

  1. Jan 9, 2007 #1
    Up until my third year EM course we have used SI and MKS units in EM. In fact every textbook i have used for EM (griffiths,wangsness) also use those units.

    My current prof wants up to learn CGS units. While they do appear much 'cleaner' (no epsilon0, mu0 for certain equations) what is their use in the real world?

    What units would a physicist in his or her day to day life of physics use?? At least in north america...

    is the cleanliness of expressions the only reason why these units are used??
  2. jcsd
  3. Jan 9, 2007 #2


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    One and only one. Just like any matter of notation or convention, the advice is learn one well and apply it everywhere. If you're taught in SI/MKS, then you'd better look for sources which use this system of units. Actually, tou'll see that atomic physics uses other system of units, particle physics/QFT another and i don't see the point of making your life more difficult using both MKS and CGS for electrodynamics.

  4. Jan 9, 2007 #3
    to bad my prof doesnt see it this way

    i need to learn CGS now

    now its gonna be hard to even think i get the right answer :cry:
  5. Jan 9, 2007 #4
    It usually depends on what scale you're working in--for instance atomic masses are measured in grams/mol rather than the SI unit kilograms/mol (which would then require a x10^-3 by each number). It really is just about convenience.
  6. Jan 10, 2007 #5
    The nonlinear optics community also commonly uses CGS.
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