MP Board Class 12 Physics Previous Year Paper 2024 — Solv…
MP Board Class 12 Physics Previous Year Paper 2024 — completely solved with step-by-step explanations. This post covers the full Physics question paper from the MP Board 2024 exam, including all sections with detailed answers, formulas, and key concepts. Perfect for exam revision and understanding the paper pattern for the upcoming 2027 board exam.
📋 Paper Overview & Exam Pattern
The MP Board Class 12 Physics 2024 paper carried a total of 100 marks (70 marks theory + 30 marks practical). The theory paper was divided into 4 sections with the following distribution:
| Section | Type of Questions | No. of Questions | Marks per Question | Total Marks |
|---|---|---|---|---|
| A | Objective / Multiple Choice | 10 | 1 | 10 |
| B | Very Short Answer | 5 | 2 | 10 |
| C | Short Answer | 6 | 3 | 18 |
| D | Long Answer | 3 | 5 | 15 |
The remaining 37 marks were distributed across numerical problems, derivations, and diagram-based questions from all units of the Class 12 Physics syllabus.
🎯 Section A — Objective Questions (1 Mark Each)
Each question carries 1 mark. Choose the correct option.
Q1. The SI unit of electric flux is:
(a) N m²/C (b) N/C (c) V/m (d) C/m²
Answer: (a) N m²/C
Explanation: Electric flux = E·A·cosθ. Unit = N/C × m² = N·m²/C.
Q2. Which of the following has the highest resistance?
(a) Copper wire (b) Silicon (c) Glass (d) Iron
Answer: (c) Glass
Explanation: Glass is an insulator with resistivity ~10¹⁰ to 10¹⁴ Ωm, far higher than conductors or semiconductors.
Q3. The de Broglie wavelength of a particle is inversely proportional to its:
(a) Velocity (b) Momentum (c) Kinetic energy (d) Mass
Answer: (b) Momentum
Explanation: λ = h/p, so wavelength is inversely proportional to momentum p = mv.
Q4. The number of neutrons in 235U is:
(a) 92 (b) 143 (c) 235 (d) 327
Answer: (b) 143
Explanation: Neutrons = Mass number − Atomic number = 235 − 92 = 143.
Q5. Which law states that the induced emf opposes the change causing it?
(a) Ampere’s law (b) Faraday’s law (c) Lenz’s law (d) Biot-Savart law
Answer: (c) Lenz’s law
Explanation: Lenz’s law: The direction of induced emf is such that it opposes the change in magnetic flux that produced it. This is a consequence of conservation of energy.
📝 Section B — Very Short Answer Questions (2 Marks Each)
Q6. What is the principle of a transformer? State its two types.
Answer: Mutual induction
Explanation: A transformer works on the principle of mutual induction — when an alternating current flows through the primary coil, it produces a changing magnetic flux in the core, which induces an emf in the secondary coil. Two types: Step-up transformer (Vs > Vp) and Step-down transformer (Vs < Vp).
Q7. Define electric dipole moment. Give its SI unit.
Answer: p = q × 2a (Coulomb-metre)
Explanation: Electric dipole moment is the product of the magnitude of either charge (q) and the distance between the charges (2a). It is a vector quantity directed from negative to positive charge. SI unit: C·m (Coulomb-metre).
Q8. What is the Brewster angle? Write its formula.
Answer: tan θB = n₂/n₁
Explanation: Brewster angle (θB) is the angle of incidence at which reflected light is completely plane-polarized. At this angle, the reflected and refracted rays are perpendicular to each other. For light travelling from medium 1 to medium 2: tan θB = n₂/n₁.
✏️ Section C — Short Answer Questions (3 Marks Each)
Q9. Derive the expression for the electric field due to an electric dipole on its axial line.
Answer:
Consider an electric dipole with charges −q at A and +q at B separated by distance 2a. Let P be a point on the axial line at distance r from the centre O.
EP = E+q − E−q
= kq/(r−a)² − kq/(r+a)²
= kq[(r+a)² − (r−a)²] / [(r²−a²)²]
= kq[4ar] / (r²−a²)²
E = (1/4πε₀) × 2p / r³ (for r >> a)
Q10. Explain the working of a p-n junction diode as a full-wave rectifier with a circuit diagram.
Answer:
Working: A full-wave rectifier uses two diodes and a centre-tapped transformer. During the positive half-cycle of AC input, diode D₁ is forward-biased and conducts, while D₂ is reverse-biased. During the negative half-cycle, D₂ conducts and D₁ is reverse-biased. Thus, both half-cycles contribute to the output, producing a pulsating DC. A capacitor filter is used to smooth the output.
Key Points: Efficiency = 81.2%, Ripple factor = 0.48 (without filter), Uses centre-tap transformer, Requires two diodes.
Q11. State and explain Gauss’s law in electrostatics. Write its mathematical form.
Answer:
Statement: The total electric flux through a closed surface is equal to 1/ε₀ times the total charge enclosed by that surface.
Mathematical form: ∮S E·dS = Qenclosed / ε₀
Applications: Electric field due to infinite line charge (E = λ/2πε₀r), infinite sheet (E = σ/2ε₀), spherical shell (E = Q/4πε₀r² for r > R).
📐 Section D — Long Answer Questions (5 Marks Each)
Q12. Derive the expression for the magnetic field at a point on the axis of a circular current-carrying loop using Biot-Savart law.
Answer:
Consider a circular loop of radius R carrying current I. Let P be a point on the axis at distance x from the centre.
dB = (μ₀/4π) × (Idl × r̂)/r² (Biot-Savart law)
Due to symmetry, perpendicular components cancel. The axial component:
dBx = dB·sinθ = (μ₀/4π) × (Idl × R)/r³
B = ∮ dBx = (μ₀/4π) × (IR/r³) × ∮ dl = (μ₀/4π) × (IR/r³) × 2πR
Final expression: B = (μ₀IR²) / [2(R² + x²)³/²]
At the centre (x = 0): B = μ₀I/2R
Q13. Explain the phenomenon of interference of light. Derive the conditions for constructive and destructive interference in Young’s double-slit experiment.
Answer:
Interference: When two coherent light waves superpose, the resultant intensity is not the sum of individual intensities. It varies between maximum and minimum depending on the phase difference.
In Young’s double-slit experiment, two slits S₁ and S₂ act as coherent sources. Path difference = d·sinθ.
Constructive interference (bright fringe): Path difference = nλ (n = 0, 1, 2, …)
Destructive interference (dark fringe): Path difference = (2n+1)λ/2 (n = 0, 1, 2, …)
Fringe width: β = λD/d, where D = distance to screen, d = slit separation.
💡 Preparation Tips for MP Board Physics 2027
- Master the derivations: Most 5-mark questions are derivations (electric field, magnetic field, interference, etc.). Practice writing them step-by-step with proper diagrams.
- Numericals matter: Practice at least 50 numerical problems from Electrostatics, Current Electricity, Magnetism, and Optics chapters.
- Diagram-based questions: Practice drawing ray diagrams, circuit diagrams, and labelled diagrams of devices like transformer, AC generator, etc.
- Revise formula sheets: Create a consolidated formula sheet for each unit and revise it daily in the last month before the exam.
- Previous year papers: Solve at least 5-10 previous year papers to understand the question pattern, marking scheme, and frequently repeated questions.
- The 2024 paper was balanced with easy, moderate, and difficult questions.
- Section A (MCQs) — focus on conceptual understanding from NCERT.
- Section B & C — practice short and medium derivations, definitions, and laws.
- Section D — master 10-12 core derivations thoroughly.
- Time management: 70 marks in 3 hours = roughly 2.5 minutes per mark.