In an RL circuit with alternating current, the current lags behind the voltage. What does this mean, and how can it be explained qualitatively, based on the phenomenon of electromagnetic induction?

Question: Explain the meaning of the statement "the current lags behind the voltage" in an RL circuit with alternating current, and qualitatively describe the role of electromagnetic induction in this phenomenon. Answer: In an RL circuit with alternating current, the statement "the current lags behind the voltage" means that the current waveform reaches its peak at a later time than the voltage waveform, with a phase difference between them. This occurs due to the phenomenon of electromagnetic induction. When current flows through the inductor, it creates a changing magnetic field, which induces an electromotive force (EMF) in the coil that opposes the change in current according to Lenz's law. The induced EMF is at its maximum when the rate of change of current is highest, which is when the voltage waveform reaches its peak. This results in the current waveform reaching its peak later, causing the current to lag behind the voltage.