Question: Assertion (A) : Lenz's law is a consequence of the law of conservation of energy. Reason (R) : There is no power loss in an ideal inductor.

Step 1 (Governing Law & Analysis): [0.5 Mark]

• Assertion (A): Lenz's Law states that the polarity of induced emf is such that it opposes the change in magnetic flux that produced it. If it did not oppose the change, it would violate the Law of Conservation of Energy by creating energy out of nothing. Thus, (A) is True.
• Reason (R): An ideal inductor has zero resistance ($R = 0$). The power loss in an inductor is given by $P = I^2 R$. Since $R = 0$, the average power dissipated is $P = 0$. Thus, (R) is True.

Step 2 (Logical Deduction): [0.25 Mark]

While both statements are scientifically correct, the Reason (R) describes the property of an ideal inductor (zero ohmic resistance), whereas the Assertion (A) describes the fundamental physical principle behind electromagnetic induction (Lenz's Law). The fact that an inductor has no power loss is not the explanation for why Lenz's Law obeys the conservation of energy.

Step 3 (Final Concluded Answer): [0.25 Mark]

Correct Option: (b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

💡 EL10 Concept Insight: Think of Lenz's Law like a "nature's tax"—you have to put in work to move a magnet near a coil, and that work you do is exactly what turns into the electrical energy you get out. The fact that an inductor doesn't waste energy as heat is just a separate cool feature of ideal wires, not the reason why nature insists on balancing the energy books!