Induced EMF in an Inductor – Rankers Physics

Faraday's Law of Electromagnetic Induction: Practice Problem & Solution

Assertion (A): At any instant, if the current through an inductor is zero, then the induced emf may not be zero. Reason (R): An inductor tends to keep the flux constant.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Faraday's Law of Electromagnetic Induction. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true: The induced EMF is \(emf = -L \frac{dI}{dt}\). Even if \(I=0\) instantaneously, \(frac{dI}{dt}\) can be non-zero (e.g., during oscillation or switching). Reason (R) is true, describing Lenz's law. However, R is not the correct explanation for A, as A focuses on instantaneous values of \(I\) and \(frac{dI}{dt}\).

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