I_{3} is ahead of I_{2} by π/2 (or 90°)

Let us assume that a certain quantity I(t) changes over time as I(t) = I_{0}cos(ωt). A phasor is a vector whose length represents the amplitude I_{0} (see the diagram (Figure 1) ). This vector is assumed to rotate counterclockwise with angular frequency ω, that way, the horizontal component of the vector represents the actual value i(t) at any given moment. In this problem, you will answer some basic questions about phasors and prepare to use them in the analysis of various AC circuits.

At the moment shown in the diagram, which of the following statements is true?

A) I_{2} lags I_{3} by π

B) I_{3} lags I_{2} by 2π

C) I_{2} lags I_{3} by π/2

D) I_{3} lags I_{2} by π/2

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