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A
Series circuit
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B
Parallel circuit
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C
Short circuit
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D
Open circuit
Why this is the answer
Circuit topologies: SERIES — components connected end-to-end in a single path; only ONE PATH for current; SAME CURRENT through every component; voltage DIVIDES among components (V_total = V₁ + V₂ + V₃...). Resistances ADD (R_total = R₁ + R₂ + R₃). Adding more components increases total resistance, decreases current. Failure of one component (open) breaks the entire circuit. Examples: old Christmas lights (one bulb out = all dark); switches and protective devices in line with loads; voltage divider circuits. PARALLEL — components connected across the same two nodes; MULTIPLE PATHS for current; SAME VOLTAGE across every component; current DIVIDES among branches (I_total = I₁ + I₂ + I₃...). Reciprocal resistances add: 1/R_total = 1/R₁ + 1/R₂ + 1/R₃. Total resistance is LESS than smallest individual resistance. Failure of one component does NOT break others. Examples: household wiring (multiple outlets in parallel — one device off doesn't affect others); modern LED Christmas lights; speakers wired in parallel. OPEN CIRCUIT — break in the circuit; no current can flow; infinite resistance. SHORT CIRCUIT — unintended low-resistance path bypassing the load; very high current; can cause damage, fire, or trip breakers. Why parallel for household wiring: each appliance gets full line voltage (120V) regardless of others; turning off one appliance doesn't affect others; failure of one doesn't affect others. Series-parallel combinations: real circuits often combine both; analyze by reducing parallel groups to equivalent resistances, then summing series elements. Kirchhoff's Laws: (1) VOLTAGE LAW (KVL): sum of voltage changes around any closed loop = 0; (2) CURRENT LAW (KCL): sum of currents into any node = sum of currents out. Used to analyze complex circuits. ASVAB EI commonly tests series vs parallel identification and calculation.
Source: ASVAB EI, Circuit Types