### An introduction to power boxes

This simulation aims to acquaint you with the concept of power boxes, as introduced in a September 2018 article in The Physics Teacher, by Daryl McPadden, Jason Dowd, and Eric Brewe, titled "Power Boxes: New Representation for Analyzing DC Circuits". Note that one way to calculate power is to multiply the voltage and the current. In this simulation (and others below), the voltage is plotted on the vertical axis and the current on the horizontal axis, meaning that the rectangular area shown in the power box represents the power for that particular circuit element.

This simulation shows the power boxes for a very simple case - a circuit with a single battery and a single resistor. At the top left, the black region on the power box shows the power input to the circuit by the battery. At the top right, the blue region shows the power dissipated as thermal energy and/or light by the resistor / light bulb. Note the thick black line at the bottom of that power box, to indicate that there is still a current in the bottom wire in the circuit, even though the voltage has dropped to zero after the current has passed through the resistor.

The power box at the bottom right is a summary for the circuit.

Adjust the sliders, to see the impact on the power boxes of adjusting the battery voltage and the resistance of the resistor. Once you are comfortable with this simulation, move on to see the power boxes representation for more complicated circuits.

Simulation written by Andrew Duffy, and first posted on 11-20-2018.