An inductor is connected to a direct voltage | vedclass

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(B) The correct answer is $B$. When a switch is closed in a circuit containing an inductor and a $DC$ source,the current grows from $0$ to its steady-

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$A$ larger $emf$ is induced when the switch is opened.

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(B) The correct answer is $B$. When a switch is closed in a circuit containing an inductor and a $DC$ source,the current grows from $0$ to its steady-state value $I = V/R$. During this growth,there is a change in magnetic flux,inducing a back $emf$. However,when the switch is opened,the current drops from its steady-state value to $0$ almost instantaneously. According to Faraday's law,$e = -L(di/dt)$. Since the time interval $dt$ for opening the switch is extremely small,the rate of change of current $di/dt$ is very high. Therefore,a very large $emf$ is induced when the switch is opened,often causing a spark across the switch contacts.

An inductor is connected to a direct voltage source through a switch. Which of the following statements is true regarding the induced electromotive force $(emf)$?

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