In an electric circuit, which of the following components prevents the flow of $e-$ (electrons) and stops current from passing through the circuit?

• A. A conducting wire
• B. A resistor
• C. A closed switch
• D. An open switch

Answer: (D)

Verified step by step guidance

1. Understand the role of each component in an electric circuit: a conducting wire allows electrons to flow freely, a resistor limits the flow of electrons by providing resistance, and a switch controls whether the circuit is complete or broken.
2. Recall that current flows only when the circuit is closed, meaning there is a continuous path for electrons to move through.
3. Recognize that a closed switch completes the circuit, allowing current to pass, while an open switch breaks the circuit, preventing current flow.
4. Identify that the component which stops current from passing through the circuit is the open switch, as it creates a gap that electrons cannot cross.
5. Conclude that the open switch effectively prevents the flow of electrons and stops current, unlike a resistor or conducting wire which allow current to flow (though the resistor limits it).