PhET Tutorial: Circuit Construction Kit - DC Circuits with Resistors in Series and in Parallel Let's start with a simple circuit that you will have seen in the Ohm's Law and Power PhET tutorial, if you completed that one. What is the voltage reading across the resistor, as shown in the figure below? You should see the blue electrons flowing through the circuit, whereas (conventional) current is the flow of positive charge. You can select which current to display in the panel in the upper-right corner. 9.0 V 13 of 28 10.00