Nikola Tesla Articles
Induction-Coil Potentials Page 578
Philosophical Magazine - April 1st, 1914
was then unusually large, and these large amplitudes were alone selected for measurement. The iron-steel interruptor gave much more variable results than the other, but at its best was quite equal to the mercury interruptor.
A number of curves was first taken for different values of the primary current, in order to see whether the amplitude of the curve is proportional to the square of the current. Table VI. contains a set of results for Case I., the current being given in amperes and the amplitude \(A\) of the curve in millimetres.
Table VI.
| \(i_0\). | \(A\). | \(\sqrt{A}/i_0\). |
|---|---|---|
| 1·83 | 3·1 | ·962 |
| 2·81 | 7·8 | ·994 |
| 3·75 | 14·0 | ·998 |
| 4·91 | 23·3 | ·983 |
| 4·91 | 10·5 | ·660 |
| 6·41 | 16·9 | ·641 |
The last two plates were taken after the sensitiveness of the electrometer had been reduced by tightening the strip. In cases where the deflexion on the plate is over 3 cm. the photograph is generally very faint, and such large angular deflexions of the reflected ray probably cease to be proportional to the deflecting force.
The numbers in the third column of Table VI. show that over the range of this set of readings the maximum potential \(V_m\) at the electrometer is within 4 per cent. proportional to the current interrupted in the primary coil. Similar results were obtained, within the same limits, from the plates taken for Cases II. and III. The numbers given in the table also point to a maximum value of the ratio \(V_m/i_0\), in the neighbourhood of 4 amperes, a result which might be expected from the manner in which \(L_{21}\) varies with \(i_0\), as shown in Table I.
A set of three plates was next taken for the three cases with the same primary current, in order to see whether the maximum potentials are proportional to the calculated values. The results are given in Table VII. in which \(V_c\) represents the calculated value in volts of the maximum potential. In each case \(i_0\) was 3·0 amperes.
