Which device resists the flow of electrical current?

• A. Resistor
• B. Switch
• C. Diode
• D. Capacitor

Answer: (A)

A resistor provides opposition to current flow. Its job is to limit how much current can pass for a given voltage, which is described by Ohm’s law: current equals voltage divided by resistance. The higher the resistance, the less current flows, and the resistor also converts some of that electrical energy into heat, helping to control voltages and protect other components.

A switch isn’t about resistance; it’s a control device that either completes the circuit (low resistance) or breaks it (no current). A diode conducts primarily in one direction and has a forward voltage drop rather than a fixed resistance. A capacitor stores energy and blocks steady direct current after charging, though it can pass transient or alternating current depending on frequency. It doesn’t provide a simple, constant opposition to current like a resistor does.

So, the device that resists the flow of electrical current in the most direct, constant way is the resistor.