Which set of elements best represents a complete circuit?

Which set of elements best represents a complete circuit?

• A. Power source, switch, load
• B. Power source, resistor, capacitor
• C. Load, switch, conductor
• D. Power source only

Answer: (B)

A complete circuit needs a source of energy, a return path for current, and something that uses or stores energy in the loop. The combination of a power source, a resistor, and a capacitor covers all three roles: the power source provides the driving force, the resistor is the load that consumes energy, and the capacitor completes the loop by storing energy as current flows to charge it. This makes a closed path for current to travel through the circuit. The other setups either risk being incomplete if a switch is open, lack a power source to drive current, or don’t include a component that forms a proper return path in the loop.

A complete circuit needs a source of energy, a return path for current, and something that uses or stores energy in the loop. The combination of a power source, a resistor, and a capacitor covers all three roles: the power source provides the driving force, the resistor is the load that consumes energy, and the capacitor completes the loop by storing energy as current flows to charge it. This makes a closed path for current to travel through the circuit. The other setups either risk being incomplete if a switch is open, lack a power source to drive current, or don’t include a component that forms a proper return path in the loop.