(II) (a) In Fig. 30-28a, assume that the switch S has been

Chapter , Problem 27

(choose chapter or problem)

(II) (a) In Fig. 30-28a, assume that the switch S has been inposition A for sufficient time so that a steady currentI0 = V0/R flows through the resistor R. A t time t = 0, theswitch is quickly switched to position B and the currentthrough R decays according to I = /0 e~^T. Show that themaximum emf %nax induced in the inductor during this timeperiod equals the battery voltage Vo- (b ) In Fig. 30-28b,assume that the switch has been in position A for sufficienttime so that a steady current 70 = V0/R flows through theresistor R. A t time t = 0, the switch is quickly switched toposition B and the current decays through resistor R'(which is much greaterthan R) according toI = Ioe~t/T'. Show thatthe maximum emf %naxinduced in the inductorduring this time period is(R '/R )V 0. I f R ' = 55Rand V0 = 120 V, determine^nax. [When amechanical switch isopened, a high-resistanceair gap is created, whichis modeled as R r here.This why high-voltage sparkingcan occur if a currentcarryinginductor issuddenly cut o ff from itspower source.]