Magnetism and electromagnetismQuestion 1069 of 1506

In an iron-core coil on AC, how does the core flux compare with the applied voltage?

It leads the voltage by 90 degrees
It is in phase with the voltage
It lags the voltage by 90 degrees
It is 180 degrees from the voltage

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Correct answer: It lags the voltage by 90 degrees

The voltage is proportional to the rate of change of flux, so the flux is a quarter cycle behind.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 10.1: Mutual Inductance and Basic Operation

Questions last reviewed: 18 October 2026

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