Series circuits — definition check without a diagram: A correct identification rule is: “Two components are in series if the same current flows through both, sharing a single uninterrupted path with only one common node between them.” Evaluate this definition for correctness.

Introduction / Context:
Many textbook questions rely on a figure to decide whether components are in series or parallel. Applying the Recovery-First Policy, we remove the dependency on a missing diagram and test the core definition instead. Knowing the precise topological rule lets you identify series connections in any circuit drawing.

Given Data / Assumptions:

• Ideal wires and lumped components.
• No branching between the two devices under test.
• Current continuity is the criterion, not physical proximity.

Concept / Approach:
Components are in series if the same current must pass through them sequentially because there is only one path for current flow. This means the junction between them connects to nothing else (no additional branches). Parallel elements instead share the same two nodes and therefore the same voltage, not necessarily the same current. The series criterion is independent of component values and source type (DC or AC).

Step-by-Step Solution:

Verification / Alternative check:
Apply Kirchhoff’s laws: the same branch current flows through series components; voltages add according to Ohm’s law, consistent with the definition.

Why Other Options Are Wrong:

• Incorrect: Conflicts with the standard topological definition.
• Applies only to DC: AC behavior still follows the same series topology.
• Valid only if resistances equal: Series status does not depend on values.
• Depends on supply polarity: Polarity does not change network topology.

Common Pitfalls:
Judging by physical layout instead of connectivity; mistaking a node with hidden branches for a pure series junction; assuming equal current implies equal voltage (it does not).

Final Answer:
Correct