)} | e^{+(R/L)t} | i_{t} |
--------------+--------------+---------|
| 0 | 1 | 0 |
| 1 | 1.105 | 0.950 |
| 2 | 1.221 | 1.810 |
| 5 | 1.649 | 3.936 |
| 10 | 2.718 | 6.343 |
| 20 | 7.389 | 8.646 |
| 30 | 20.08 | 9.501 |
| 60 | 403.4 | 9.975 |
| 120 | 16200.0 | 9.999 |
----------------------------------------
In this case the value of the steady current as calculated by Ohm's
law is 10 amperes, but Helmholtz's law shows us that with the great
self-induction which we have assumed to be present, the current, even
at the end of 30 seconds, has only risen up to within 5 percent. of
its final value; and only at the end of two minutes has practically
attained full strength. These values are set out in the highest curve
in Fig. 54, in which, however, the further supposition is made that
the number of spirals, S, in the coils of the electromagnet is 100, so
that when the current attains its full value of 10 amperes, the full
magnetizing power will be Si = 1000.
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