﻿the 
  Photoelectric 
  Effect. 
  

  

  561 
  

  

  energy 
  was 
  small, 
  so 
  that 
  

  

  small 
  and 
  in 
  the 
  ultra-violet 
  the 
  

   in 
  both 
  parts 
  of 
  the 
  spectrum 
  it 
  was 
  found 
  best 
  to 
  use 
  fairly 
  

   wide 
  slits 
  and 
  strips. 
  The 
  effect 
  of 
  this 
  width 
  of 
  slits 
  will 
  

   be 
  considered 
  when 
  the 
  experimental 
  results 
  are 
  discussed. 
  

  

  Experimental 
  Results. 
  

   Platinum. 
  — 
  The 
  experimental 
  results 
  in 
  the 
  case 
  of 
  platinum 
  

   are 
  given 
  in 
  Table 
  III. 
  X 
  and 
  v 
  are 
  the 
  wave-length 
  and 
  

   frequency 
  of 
  the 
  incident 
  light, 
  d 
  l 
  and 
  d 
  2 
  are 
  deflexions 
  of 
  

   the 
  electrometer 
  per 
  half 
  minute, 
  d 
  is 
  the 
  average 
  of 
  d 
  1 
  and 
  d 
  2 
  , 
  

   E 
  is 
  the 
  energy 
  of 
  the 
  incident 
  light 
  in 
  arbitrary 
  units, 
  and 
  N 
  

   is 
  proportional 
  to 
  the 
  number 
  of 
  electrons 
  emitted 
  per 
  unit 
  

   time 
  by 
  light 
  of 
  unit 
  intensity. 
  The 
  readings 
  were 
  taken 
  in 
  

   order 
  down 
  the 
  column 
  d 
  x 
  and 
  then 
  up 
  the 
  column 
  d 
  2 
  . 
  The 
  

   averages 
  should 
  be 
  relatively 
  independent 
  of 
  any 
  fatigue 
  

  

  Table 
  III. 
  Platinum. 
  

  

  X. 
  

  

  v. 
  

  

  d 
  x 
  . 
  

  

  d 
  2 
  . 
  

  

  d. 
  

  

  E. 
  

  

  d 
  

  

  200/i/i 
  

  

  150(10)13 
  

  

  34 
  

  

  32 
  

  

  33 
  

  

  1-00 
  

  

  33 
  

  

  202 
  

  

  1485 
  

  

  31 
  

  

  29 
  

  

  30 
  

  

  1-00 
  

  

  30 
  

  

  204 
  

  

  147 
  

  

  23 
  

  

  24 
  

  

  23-5 
  

  

  0-83 
  

  

  27 
  

  

  214 
  

  

  140 
  

  

  44 
  

  

  40 
  

  

  42 
  

  

  1-7 
  

  

  25 
  

  

  220 
  

  

  136 
  

  

  58 
  

  

  51 
  

  

  54-5 
  

  

  20 
  

  

  27 
  

  

  230 
  

  

  130 
  

  

  71 
  

  

  62 
  

  

  66-5 
  

  

  41 
  

  

  16 
  

  

  240 
  

  

  125 
  

  

  55 
  

  

  50 
  

  

  52-5 
  

  

  6-3 
  

  

  8-3 
  

  

  254 
  

  

  118 
  

  

  34 
  

  

  31 
  

  

  32-5 
  

  

  24-3 
  

  

  1-5 
  

  

  260 
  

  

  1155 
  

  

  16 
  

  

  14 
  

  

  15 
  

  

  227 
  

  

  0-7 
  

  

  270 
  

  

  111 
  

  

  5 
  

  

  5 
  

  

  5 
  

  

  16-6 
  

  

  0-3 
  

  

  280 
  

  

  107 
  

  

  1 
  

  

  4 
  

  

  2-5 
  

  

  14-5 
  

  

  02 
  

  

  290 
  

  

  103-5 
  

  

  

  

  1 
  

  

  0-5 
  

  

  21-2 
  

  

  0-02 
  

  

  300 
  

  

  100 
  

  

  

  

  

  

  

  

  43-5 
  

  

  

  

  Fier. 
  4. 
  

  

  N 
  

  

  40 
  

  

  so 
  

  

  10 
  

  

  10 
  

   

  

  pt 
  

  

  

  

  

  

  

  

  

  

  

  A 
  

  

  • 
  

  

  / 
  • 
  

  

  

  

  

  

  / 
  

  

  A 
  

  

  

  

  

  

  

  

  

  

  

  90 
  100 
  110 
  

  

  120 
  

  

  V 
  

  

  no 
  

  

  ifl)13 
  

  

  140 
  150 
  

  

  effect. 
  The 
  relation 
  between 
  X, 
  v, 
  and 
  N 
  is 
  shown 
  graphically 
  

   in 
  fig. 
  I, 
  curve 
  1. 
  Curve 
  2 
  is 
  the 
  graph 
  of 
  equation 
  (6), 
  the 
  

   ordinates 
  being 
  in 
  arbitrary 
  units. 
  

  

  