Trap 1 — Series vs Parallel Power: Students think "more components = more power in series." Wrong. P ∝ 1/R_eq; parallel has lower R_eq → much more power. For n equal resistors: P_parallel = $n^{2}$ × P_series.

Trap 2 — Potentiometer vs Voltmeter: Voltmeter measures terminal voltage V = ε − Ir (always < ε). Potentiometer measures TRUE EMF at null point because no current flows. Never say "potentiometer has higher resistance" as the reason — the real reason is zero current at null.

Trap 3 — Metre Bridge Interchange: If balance point is at l, interchanging R and S gives l′ = 100 − l, NOT the same position.

Trap 4 — Short Circuit Terminal Voltage: When a cell is short-circuited (R = 0), terminal voltage = 0, NOT ε. All EMF is dropped across internal resistance. Current I = ε/r (not infinite).

Trap 5 — Semiconductor vs Metal Temperature: Students often state "all resistances increase with temperature." Semiconductors DECREASE. NTC thermistors are semiconductors.

Trap 6 — Charging vs Discharging Terminal Voltage: During discharging: V = ε − Ir (V < ε). During charging: V = ε + Ir (V > ε). Students apply ε − Ir for both cases.

Trap 7 — Wheatstone Bridge Reciprocity: Students think interchanging battery and galvanometer in a balanced bridge destroys balance. It does NOT (reciprocity theorem). Balance depends only on the four resistances.

Trap 8 — Resistivity vs Resistance: Resistivity is a material property (independent of shape/size). Resistance depends on both material AND geometry. A longer thinner wire of the same material has higher R but same ρ.

Trap 9 — Potentiometer Consistency Check: Students solve for balance length without checking if it is possible. Always verify: V_wire ≥ ε_test. If V_wire < ε_test, no balance is possible.

Trap 10 — Parallel Power Formula in Series: Using P = $V^{2}$/R (parallel formula) in a series circuit gives wrong answer. In series, same I — use P = $I^{2}$R. In parallel, same V — use P = $V^{2}$/R.