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An electromagnet has stroed 648 J of magnetic energy, when a current of 9 A exists in its coils. What average e.m.f. is induced if the current is reduced to zero in 0.45 |
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Answer» Her, `E = 648 J, I = 9 A, e =?` `dI = 9 - 0 = 9 A, dt = 0.45 s` From `E = (1)/(2) LI^(2)` `648 = (1)/(2) xx L (9)^(2)`, `L = (648 xx 2)/(9 xx 9) = 16 H` As `e = (L dI)/(dt) :. e = (16(9))/(0.45) = 320 V` |
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