CBSE Class 12 Physics Current Electricity PYQs Analysis (2021-2025)

Based on detailed analysis of last 5 years' papers. Perfect for 2026 Boards prep!

Key Trends

Weightage Breakdown: 1-3 MCQs/assertion-reason (1 mark), 1-2 short answers (2 marks), 1-2 numericals/derivations on Kirchhoff/potentiometer (3-5 marks), occasional case-based.
Repeated Topics: Drift velocity & mobility, resistivity & temperature dependence, Ohm's law limitations, series/parallel combination of resistors, Kirchhoff’s laws (junction & loop rule), Wheatstone bridge & meter bridge, potentiometer (comparison of emf & internal resistance), power dissipation (heating effect), cells in series/parallel.
Difficulty: Medium; Kirchhoff’s laws applications & potentiometer numericals are most repeated & scoring.
Changes: More numericals on potentiometer (null point shifts) and combination of cells in 2023–2025.

Most Important and Repeated Questions

Question Example	Type/Marks	Years Repeated	Notes
Using Kirchhoff’s laws, find current in each branch of a given circuit (usually wheatstone-like unbalanced bridge or ladder network with 4–6 resistors & cells).	Long Numerical (4-5 marks)	2021, 2022, 2023, 2024, 2025	Repeated 5x; Assign currents → apply junction rule → loop equations → solve simultaneous equations.
Explain working of potentiometer. How to find emf of a cell or internal resistance of a cell using potentiometer.	Short Answer/Derivation (3 marks)	2021 Term 2, 2022, 2023, 2024	Repeated 4x; Null point → balancing length l1 for known E, l2 for test cell → E2/E1 = l2/l1; for r: switch on shunt, new l3 → r = R (l1-l3)/l3.
A battery of emf E and internal resistance r is connected to external resistance R. Find current, terminal voltage, power dissipated. Also maximum power condition.	Numerical/Short Answer (3 marks)	2022, 2023, 2024, 2025	Repeated 4x; I = E/(R+r), V = IR = E - Ir; P = I²R max when R = r → P_max = E²/(4r).
Assertion: In Wheatstone bridge, when balanced, no current flows through galvanometer. Reason: Potential difference across galvanometer becomes zero.	Assertion-Reason (1 mark)	2023, 2024, 2025	Repeated 3x; Both true, reason explains.
Resistivity of a material is ρ. How does it change with temperature? Derive temperature dependence formula (ρ = ρ₀(1+αΔT)).	Short Answer (2-3 marks)	2021 Term 1, 2022, 2023, 2025	Repeated 4x; Resistance R = R₀(1+αΔT) → ρ = ρ₀(1+αΔT) as length/area change negligible.
Meter bridge: Unknown resistance X in one gap, known R in other. Balance at l cm. Find X = R (l/(100-l)).	Short Answer (2 marks)	2022, 2024	Repeated 2x; Wheatstone principle: P/Q = l/(100-l) → X = R (l/(100-l)).
MCQ: Drift velocity vd of electrons is proportional to: (a) electric field E (b) 1/E (c) E² (d) √E	MCQ (1 mark)	2021 Term 1, 2023, 2024	Repeated 3x; Answer (a) vd = eEτ/m → vd ∝ E.
Two cells of emf E1, E2 and internal r1, r2 connected in parallel. Find equivalent emf & r.	Short Answer (3 marks)	2023, 2025	Repeated 2x; E_eq = (E1 r2 + E2 r1)/(r1 + r2), r_eq = r1 r2/(r1 + r2).
Case-based: Given circuit with cells & resistors, apply Kirchhoff’s laws or find equivalent resistance/power.	Case-Based (4 marks)	2023, 2025	Repeated 2x; Use loop/junction rules or symmetry for equivalent R.
Find power dissipated in a resistor when connected to battery with internal resistance.	Numerical (2-3 marks)	2021 Term 2, 2024	Repeated 2x; P = I²R = (E/(R+r))² R.

Best Format for Preparation and Answering

Study Format: Memorize Kirchhoff’s rules, potentiometer applications & formulas for drift velocity/resistivity. Practice circuit numericals daily (assign currents, write equations). Draw clear circuit diagrams.
Answer Format: Circuits: Label currents → apply junction & loop rules → solve equations → box final current/voltage. Potentiometer: Show balancing length → formula → calculate emf/r. Always include units.
Tips: Kirchhoff’s laws applications & potentiometer (emf/internal r) are highest repeat & marks. Practice Wheatstone/meter bridge balancing conditions. Time: 10–12 mins for 4–5 mark questions. Very scoring if steps are systematic.

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