Resistance measures how strongly a component opposes current. Use R = V/I, with resistance in ohms. At fixed potential difference, increasing resistance decreases current; this concerns charge flow per second rather than charge being used up. Example: At fixed potential difference a resistor’s resistance doubles. Explain the current change. I = V/R, so the current halves; fewer coulombs pass per second. A correct answer needs an appropriate unit as well as a numerical value. Justify your answer.