Nikola Tesla Books
Books written by or about Nikola Tesla
Colorado Springs
Nov. 2, 1899
Readings were again taken today to ascertain the value found yesterday for inductance of new extra coil. The results were as follows:
| E | I | Ï | R | } | average of three reading very closely agreeing. |
|---|---|---|---|---|---|
| 194 | 10.7 | 887 | 2.664 |
| $! {\left({E \over I}\right)} $! = 18.13 | $! {\left({E \over I}\right)^{2}} $! = 328.6969 |
| R2 = 7.0969 | |
| $! {{\left({E \over I}\right)^{2}} - R^{2}} $! = 321.60 | |
| L = $! {\sqrt{321.6} \over 887} $! = $! {17.933 \over 887} $! | |
L = 0.0202176 henry or 20,217,600 cm.
This is a value a little smaller than the one found yesterday but it is within the limits of variation of Ï.
Note: When the turns are far apart the ordinary formulas for calculating do not apply, and the measured value is the more inferior to the calculated value the greater the turns and the farther apart they are. When very far apart it is better to calculate inductance of one turn and multiply or, if they are not all alike, to calculate then separately and add up, making some allowance for mutual induction.
Secondary last form, two wires No. 10 in multiple 17 turns on frame described on another occasion. To test the values before found for inductance and mutual induction coefficient readings were again taken today. For secondary inductance:
| E | I | Ï | R | } | The first two reading were in all probability the best and they are taken. | |
|---|---|---|---|---|---|---|
| 138 | 16.5 | } | 887 | 1.382 | ||
| 138 | 16.5 | |||||
| 136 | 16.3 | } | 875 | |||
| 134.5 | 16.2 | |||||
From above:
| $! {E \over I} $! = 8.364 | $! {\left({E \over I}\right)^{2}} $! = 69.9565 R2 = 1.91 |
} | $! {{\left({E \over I}\right)^{2}} - R^{2}} $! = 68.0465 Ï = 887 |
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