What does the representation R1 || R2 indicate in a circuit?

• A. In series
• B. Not connected
• C. In series-parallel
• D. In parallel

Answer: (D)

Parallel connection. When two resistors share the same two connection points, they are in parallel, so the voltage across both is the same while the current splits between them. Because of this, the total resistance looking into the pair is lower than either resistor individually, given by R_eq = (R1 × R2) / (R1 + R2). For example, if R1 is 4 Ω and R2 is 6 Ω, the equivalent resistance is 2.4 Ω. This is different from a series arrangement, where the current is the same through both and the voltages add, or a not-connected path, which would stop current flow.