While the slider moved up to 0·30 volt, the immediate galvanometer reading was 171 divisions, and by the time the slider had commenced its backward movement to the left (producing a diminution of E. M. F.), the current value had risen from 171 to 197·5; the conductivity had gone on increasing, the resistance having fallen from 1,754 to 1,520 ohms.
I now give a table of results for electromotive variation of wider range from 0·1 to 0·6 volt.
Table V .—Showing the Current and Conductivity Variation of a Single-point Iron Receiver, due to Cyclic Electromotive Variation of Comparatively Large Range but Short of Critical Point
| E in volt. | G. deflection, 1 dn=1/106 amp. | Resistance in ohms. | ||||||
| Direct. | Return. | Direct. | Return. | |||||
| 0·05 0·20 0·35 0·50 0·60 |
1·5 8·0 34·0 154·0 320·0 |
13 58 145 346 |
33,333 25,000 10,294 3,246 1,875 |
3,846 3,448 2,414 1,445 |
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In the previous case it was shown that with a cyclic variation of the moderate range of 0·25 volt, the resistance was reduced to 8/10ths; in this case, at double the range, the reduction is very much greater, for the resistance falls to nearly 1/10th of its original value.
This confirms the conclusion previously made that the greater the range of electromotive variation the greater is the reduction of resistance.
