In an introductory circuits context, which device restricts electric current flow to a single direction?

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

Answer: (B)

Verified step by step guidance

1. Understand the function of each device listed: a resistor limits the amount of current but does not control its direction; an inductor opposes changes in current but allows current flow in both directions; a capacitor stores and releases electrical energy but also allows alternating current to pass.
2. Recall that a diode is a semiconductor device designed to allow current to flow primarily in one direction, effectively acting as a one-way valve for electric current.
3. Recognize that the key property of a diode is its ability to restrict current flow to a single direction, which is essential in circuits where controlling the direction of current is necessary.
4. Compare this property with the other devices listed and note that none of them restrict current flow to a single direction like a diode does.
5. Conclude that the device which restricts electric current flow to a single direction is the diode.