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[¦self in¦dək·shən]
The production of a voltage in a circuit by a varying current in that same circuit.



the appearance of an electromotive force (emf) of induction in a conducting circuit when the current in the circuit changes. This phenomenon is a special case of electromagnetic induction. The current change in the circuit causes a change in the magnetic flux through the surface enclosed by the circuit. As a result, an emf—the emf of self-induction—is induced in the circuit. The direction of the emf is determined by Lenz’s law: if the current in the circuit increases, the emf of self-induction opposes this increase; if the current decreases, the emf opposes the decrease. Thus, self-induction is similar to the phenomenon of inertia in mechanics. The emf of self-induction eL is proportional to the rate of change of the current i and to the self-inductance L of the circuit: eL = - Ldi/dt.

Because of self-induction, the closing of an electric circuit containing a constant emf does not instantaneously establish a steady current; the current is established only after a certain time interval (see TRANSIENT). Similarly, when the circuit is opened, the current flow does not cease instantaneously. The emf of self-induction that is induced by the opening of the circuit can be several times greater than the emf of the source. In AC circuits, the emf of self-induction causes the current in an inductance coil to lag in phase behind the voltage across the ends of the coil by (see ALTERNATING CURRENT).

The phenomenon of self-induction plays an important role in electrical engineering and radio engineering. Self-induction causes the recharging of a capacitor connected in series with an inductance coil (see OSCILLATORY CIRCUIT); as a result, natural electromagnetic oscillations are established in the circuit.


Kalashnikov, S. G. Elektrichestvo. Moscow, 1970. (Obshchii kurs fiziki, vol. 2.)


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Despite liberal abortion laws and previous reductions in maternal mortality attributable to unsafe abortion, SA continues to face problems with unsafe abortion and a relatively high rate of self-induction.
In two recent US studies, self-induction was reported by 4.
Although not significant, the results from our exploratory study show that self-induction was more common among African language-speaking and unemployed women, and that it was not associated with educational level or housing type (which was used as a proxy for socioeconomic status).
The most common methods for self-induction in this population involved the use of remedies and herbal products rather than medications procured from backstreet providers.
Use of physical trauma for self-induction after the legalisation of abortion services in SA had dramatically reduced by 2005 [6] and was absent in our sample.
Our interpretations of prevalence and methods of self-induction are therefore not generalisable to women outside the formal healthcare system, those with incomplete abortions resulting from self-induction, or those presenting for abortion in the first trimester of an unwanted pregnancy.
We aimed to identify recurring patterns and outliers of the varying situations in which women attempted self-induction.
At the time of their last self-induction attempt, three participants were living in countries where abortion was legally restricted: Uganda, Nigeria and the Dominican Republic.
Table 1 provides information about the women, their self-induction experiences and the methods they used.
Maim was the most commonly used method of self-induction overall (n=8), and all those who reported using it were living in New York or Boston and were aged 19 years or less at the time.
Finally, one woman reported using cocaine and alcohol to attempt self-induction.
Seven never confirmed their pregnancies with a test or clinic visit but believed they were pregnant and said their periods returned after self-induction (Figure 2).