Final answer:
The assertion that current may increase or decrease by inserting a ferromagnetic rod in an LCR circuit is correct, but the reason given, an increase in reactance, is not the correct explanation. It's actually the change in inductance that affects the current, making answer B correct.
Step-by-step explanation:
The question involves a series LCR circuit and the effect of inserting a ferromagnetic rod inside the circuit's inductor. The assertion that the current in the series LCR circuit may increase or decrease upon inserting a ferromagnetic rod into the inductor is correct.
This is because the insertion of the rod changes the magnetic permeability of the core, thereby affecting the inductance of the coil. However, the reason given is that the reactance (ℓL) will increase, which is not the correct explanation for the potential increase or decrease in the current. Instead, inserting a ferromagnetic rod increases the magnetic field within the inductor, resulting in a change in inductance (L) and consequently affecting the total impedance (Z) of the LCR circuit in a frequency-dependent manner.
According to Lenz's law, the induced emf will oppose the change in magnetic flux, affecting the current flowing through the circuit. The correct answer here is B: Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.