# The measured power, current, and voltage delivered to a load are 100W, 1A, and 120V respectively.? How would I find the reactive current? http://static.panoramio.com/photos/medium/94840337.jpg

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### 1 Answer

There are three different types power that can be measured in an alternative current circuit (see the attached figure).

First, it is the **Real Power** Pr which is the power that the resistive part of circuit consumes from the voltage source (or the real part of the power). It is measured in** Watts** and express the ratio (work/time) that a circuit can deliver on the exterior.

Second, it is the **Reactive Power**, Pr which is the power consumed by the reactive components of the circuit (L and C) ) (or the imaginary part of the power). It is measured in **VAR** (Volts*Amperes Reactive) and express how much power is lost from the driving source on the reactive components.

Third, it is the **Apparent Power**, Pa which is the total power that a circuit consumes from the driving voltage source (sum of the vectors **P** and **Pr**). It is measured in **VA** (Volts*Amperes).

Since in your data the power is measured in Watt, it means that it is a Real Power

`P =U*I_R` means that `I_R = P/U =100/120 =0.833 A`

This is the resistance current (or the real current).

Also from the text data, the total current that the source supply (the apparent current or total complex current) is `I_T =1 A`

From these two values and the right triangle of currents we can compute now the reactive current.

`I_X = sqrt(I_T^2 -I_R^2) =sqrt(1 -0.833^2) =0.553 A`

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