Since voltage and current no longer rise and fall together, a "PHASE SHIFT" is occurring in the circuit. In a circuit containing both inductance and resistance, which is usually the case as the inductor (a coil of wire) will have some internal resistance, the current will lag the voltage by an amount between practically 0° (nearly pure resistance) and almost −90° (nearly pure inductance). In an AC circuit however, as the voltage is continually changing, the current also continues to change, and in a purely inductive circuit, the peak values of current occur a quarter of a cycle (90°) after those of the voltage. The phase of a wave, measured in degrees, where 360 degrees is one wavelength. In DC circuits the current eventually settles to a steady state value, and the period of change prior to steady state depends on the time constant (i.e. shift in a waves position relative to a reference point.
So in an inductive circuit, current "LAGS" voltage. The leading hypothesis for winter depression (seasonal affective disorder, or SAD) is the phase shift hypothesis (PSH). This causes the current to reach its peak value some time after the voltage. Usually, a phase-shift can only be defined for two signals of the same frequency, but in this particular case, it still makes sense to define a phase-difference. This is due to phase shifts in the circuit: voltage dropped across the capacitors is out-of-phase with voltage dropped. You will discover that the voltage drops do not add up to equal the total voltage. Measure total (supply) voltage with the same voltmeter. Inductance opposes change in current due to the back emf effect. 16 columns and 12 rows, we numerically computed spatial phase shifts in systems with and without the mentioned phase shifter. Build the circuit and measure voltage drops across each component with an AC voltmeter. In a purely inductive circuit the voltage and current waveforms are not in phase. You can replace the sine with any of the other trig operations such as cosine, tangent, and cotangent. 5.1.2 Inductance in AC Circuits Inductance in AC Circuits