﻿Bifilar 
  Vibration 
  Galvanometer. 
  

  

  FiK. 
  8. 
  

  

  175 
  

  

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  *^^a:. 
  

  

  5- 
  

  

  100 
  

  

  200 
  

  

  3C0 
  400 
  500 
  600 
  

  

  700 
  

  

  r-REQUENCY 
  : 
  

  

  '\t 
  Tm 
  SECOND 
  

   C 
  U-RUENT 
  

  

  galvanometer 
  been 
  aperiodic 
  and 
  of 
  sufficiently 
  short 
  period 
  

   to 
  follow 
  the 
  alternating 
  current 
  then 
  the 
  alternating 
  current 
  

   sensibility 
  would 
  have 
  been 
  only 
  2^^2 
  = 
  2*82 
  times 
  the 
  direct 
  

   current 
  sensibility. 
  

  

  The 
  practical 
  applications 
  of 
  the 
  vibration 
  galvanometer 
  

   nearly 
  all 
  involve 
  using 
  the 
  instrument 
  in 
  some 
  form 
  of 
  

   bridge 
  or 
  null 
  method 
  for 
  determining 
  when 
  a 
  small 
  difference 
  

   of 
  potential 
  vanishes, 
  that 
  is 
  to 
  say 
  the 
  instrument 
  is 
  generally 
  

   used 
  as 
  ^ 
  a 
  sensitive 
  detector 
  for 
  small 
  alternating 
  voltages. 
  

   The 
  resistance 
  of 
  the 
  instrument 
  used 
  in 
  these 
  tests 
  is 
  

   136 
  ohms,^ 
  but 
  owing 
  to 
  the 
  back 
  E.M.F. 
  of 
  the 
  instrument 
  

   its 
  sensibility 
  as 
  a 
  voltmeter 
  must 
  not 
  be 
  calculated 
  on 
  the 
  

   basis 
  of 
  this 
  figure. 
  This 
  resistance 
  could 
  be 
  easily 
  reduced 
  

   by 
  employing 
  a 
  more 
  conducting 
  material 
  than 
  hard 
  phosphor 
  

  

  