Electrical circuits use all of the following except which?

• A. High current
• B. Low current
• C. Low resistance
• D. Voltage sources

Answer: (B)

A key idea here is that a circuit is driven by a source of electrical potential that pushes current through a closed path. To get that current, you need a voltage source to provide the push, a conductive path to carry the current, and a load with some resistance to determine how much current flows. Ohm’s law tells us I = V/R, so the actual current isn’t fixed—it depends on the voltage you apply and how much the circuit resists the flow. That means circuits can be designed to carry larger or smaller currents depending on the values chosen. The one thing that isn’t a required feature of every circuit is the current being low. Circuits naturally involve current, and its magnitude varies with design, whereas having a voltage source and a load with resistance are fundamental elements that define a circuit.