physics / fields-essential.mdon commit [english] start Ransom & Invictus notes (b0fa307)
   1# Fields - essential notes
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   3- Magnetic field always acts N -> S
   4- Current always flows +ve to -ve
   5- Motors- AC (slip ring) or DC (split ring)
   6- Dot means out of page, cross means into page
   7- ${E_1 \over E_2}={r_1 \over r_2}^2$
   8- charge produced by gravity = $GM$