Electrical Engineering ⇒ Topic : Magnitude of Selfinduced E.M.F.

Sachin
 
Magnitude of Selfinduced E.M.F. Consider a coil of N turns carrying a current of I amperes. If current in the coil changes, the flux linkages of the coil will also change. This will set up a selfinduced e.m.f. e in the coil given by
Since flux is due to current in the coil, it follows that flux linkages (= NΦ) will be proportional to I.
where L is a constant called selfinductance or inductance of the coil. The unit of inductance is henry (H). If in eq. (i) above, e = 1 volt, dEdt= 1 A/second, then L = 1 H.Hence a coil ( or circuit ) has an inductance of 1 henry ¡fan e.m.f of 1 volt is induced in it when current through it changes at the rate of 1 ampere per second. Note. The magnitude of selfinduced e.m.f. is e = Ldll dt. However, the magnitude and direct on of selfinduced e.m.f. should be written as
The minus sign is because the selfinduced e.m.f. tends to send current in the co 1 in such a direction so as to produce magnetic flux which opposes the change in flux produced by the change in current in the coil. In fact, minus sign represents Lenz's law mathematically.  
 
!! OOPS Login [Click here] is required for more results / answer