Class 12 Physics Notes Chapter 17 (Question Paper) – Examplar Problems (English) Book

Detailed Notes with MCQs of Chapter 17 from your NCERT Physics Exemplar book. Now, this chapter isn't about a specific topic like optics or electromagnetism; it's titled 'Question Paper'. Its purpose is crucial for your preparation, especially for competitive government exams. Think of it as a full dress rehearsal before the main performance.

This chapter presents a model question paper designed based on the complete Class 12 Physics syllabus and the typical examination pattern. Working through it provides invaluable practice and insight into what to expect.

Understanding Chapter 17: The Model Question Paper

1. Purpose and Significance:

• Comprehensive Revision: It forces you to recall concepts from all chapters simultaneously, testing your integrated understanding.
• Pattern Familiarity: It acquaints you with the structure, types of questions (MCQ, VSA, SA I, SA II, LA), marking scheme, and distribution of marks across different sections, which is vital for board exams and many government entrance tests.
• Time Management Practice: Solving it under timed conditions helps you develop strategies to allocate time effectively during the actual exam.
• Self-Assessment: It acts as a diagnostic tool, highlighting your strengths and weaknesses across different topics and question types. You can identify areas needing more attention.
• Application Skills: The paper includes conceptual questions, derivations, and numerical problems, testing your ability to apply theoretical knowledge.

2. Typical Structure (Based on CBSE/NCERT Pattern often mirrored in Govt. Exams):

• Section A (e.g., MCQs/VSA): Usually 1 mark each. Tests fundamental definitions, basic concepts, units, dimensions, simple formula recognition. Requires quick recall and precision.
• Section B (e.g., SA-I): Usually 2 marks each. Requires short explanations, simple derivations, circuit diagrams, or straightforward numericals. Answers should be concise but complete.
• Section C (e.g., SA-II): Usually 3 marks each. Demands more detailed explanations, standard derivations (like lens maker's formula, Biot-Savart law application), slightly complex numericals, or analysis of circuits/graphs.
• Section D (e.g., LA): Usually 5 marks each. Focuses on comprehensive derivations (like transformer, AC generator, interference/diffraction patterns), detailed explanations of principles, construction, and working of devices, or multi-step numerical problems. Often includes internal choices.

(Note: The exact structure, number of questions, and mark distribution can vary slightly year to year or between different examining bodies, but the essence remains similar. Always check the specific instructions for any exam.)

3. Key Syllabus Areas Covered (Expect questions from all these):

• Electrostatics: Coulomb's Law, Electric Field, Flux, Gauss's Theorem, Potential, Capacitance (Parallel plate, dielectrics).
• Current Electricity: Ohm's Law, Resistance, Resistivity, Kirchhoff's Laws, Cells (EMF, internal resistance), Potentiometer, Meter Bridge.
• Magnetic Effects of Current & Magnetism: Biot-Savart Law, Ampere's Law, Force on moving charge/current conductor, Torque on loop, Moving Coil Galvanometer, Magnetic Dipole Moment, Earth's Magnetism, Magnetic Materials.
• EMI & AC: Faraday's Laws, Lenz's Law, Self & Mutual Induction, AC Generator, Transformer, RMS/Peak values, Reactance, Impedance, LC Oscillations, Resonance, Power in AC circuits.
• Electromagnetic Waves: Characteristics, Spectrum (properties and uses).
• Optics:
  • Ray Optics: Reflection, Refraction, TIR, Lenses, Lens Maker's Formula, Power, Combination of Lenses, Prism, Dispersion, Optical Instruments (Microscope, Telescope).
  • Wave Optics: Huygens' Principle, Interference (YDSE), Diffraction (Single Slit), Polarisation.
• Dual Nature of Radiation & Matter: Photoelectric Effect, Einstein's Equation, Matter Waves, de Broglie relation.
• Atoms & Nuclei: Bohr Model, Hydrogen Spectrum, Nuclear Composition, Mass-Energy Relation (Binding Energy), Nuclear Fission & Fusion, Radioactivity.
• Electronic Devices: Semiconductors, P-N Junction Diode (Forward/Reverse Bias), Rectifiers (Half/Full Wave), Special purpose diodes (LED, Photodiode, Zener). (Transistors might be excluded based on recent syllabus updates, verify current syllabus).

4. Strategy for Solving the Paper (and any similar exam paper):

• Read Instructions: Don't skip this! Understand the choices, marking scheme, and any specific directives.
• Time Allocation: Mentally divide the total time based on the marks allotted to each section. Stick to it as much as possible. Don't get stuck on one question for too long.
• Choose Your Start: You can start sequentially or begin with the section you feel most confident about (e.g., Long Answers if you know the derivations well, or MCQs for a quick start).
• Answer Appropriately:
  • MCQs: Use elimination if unsure. Read options carefully.
  • VSA: Be precise. No lengthy explanations needed.
  • SA: Structure your answer. Use bullet points if helpful. Draw diagrams where necessary. Mention the formula used before substituting values in numericals.
  • LA: Be systematic. For derivations, state the principle, draw a labelled diagram, show steps clearly, and state the final result with units if applicable. For device questions, cover Principle, Construction, Working, and relevant diagrams/graphs.
• Diagrams & Graphs: Draw neat, large, and well-labelled diagrams/graphs with a pencil. They fetch marks and clarify your answer.
• Numericals:
  1. List given quantities with units.
  2. Identify the relevant formula(s).
  3. Show substitution and calculations step-by-step.
  4. State the final answer with the correct unit and appropriate significant figures.
• Units: Always write units with final answers in numericals. It's crucial.
• Review: Keep the last 10-15 minutes for revision. Check for calculation errors, missed questions, incorrect units, etc.

5. Relevance for Government Exams:

Many government exams (especially technical cadres, scientific officer roles, or general competitive exams with a science component) test fundamental concepts from Class 11/12 Physics. Practicing these Exemplar papers helps:

• Strengthen Fundamentals: Builds a solid base required for objective-type questions.
• Improve Speed & Accuracy: Essential for time-bound competitive exams.
• Develop Problem-Solving Aptitude: Hones the skills needed to tackle MCQs that often test application rather than rote learning.

Multiple Choice Questions (MCQs) - Based on Class 12 Syllabus

Here are 10 sample MCQs covering various topics, similar in style to what you might encounter:

1. A parallel plate capacitor with air between the plates has capacitance C. If the distance between the plates is doubled and the space is filled with a medium of dielectric constant K=4, the new capacitance will be:
   (a) C/2
   (b) 2C
   (c) C
   (d) 4C

2. In a Wheatstone bridge, if the battery and galvanometer are interchanged, the deflection in the galvanometer will:
   (a) Change in previous direction
   (b) Change in opposite direction
   (c) Not change
   (d) Become zero

3. An electron is moving with a velocity 'v' along the axis of a long straight solenoid carrying current I. The force experienced by the electron is:
   (a) eVB (perpendicular to axis)
   (b) eVB (along the axis)
   (c) Zero
   (d) Bev/2

4. In a purely inductive AC circuit, the current:
   (a) Lags behind the voltage by π/2
   (b) Leads the voltage by π/2
   (c) Is in phase with the voltage
   (d) Lags behind the voltage by π/4

5. Which of the following electromagnetic waves has the highest frequency?
   (a) Radio waves
   (b) Microwaves
   (c) X-rays
   (d) Gamma rays

6. In Young's double-slit experiment, the fringe width is β. If the entire setup is immersed in a liquid of refractive index μ, the new fringe width will be:
   (a) βμ
   (b) β/μ
   (c) β/μ²
   (d) βμ²

7. The work function of a metal is 4.2 eV. If light of wavelength 2000 Å falls on it, the maximum kinetic energy of emitted photoelectrons is approximately: (Use hc = 12400 eV Å)
   (a) 2.0 eV
   (b) 6.2 eV
   (c) 4.2 eV
   (d) 10.4 eV

8. The ratio of radii of nuclei with mass numbers 27 and 64 is:
   (a) 3:4
   (b) 4:3
   (c) 9:16
   (d) 27:64

9. In the Bohr model of the hydrogen atom, the radius of the nth orbit is proportional to:
   (a) n
   (b) n²
   (c) 1/n
   (d) 1/n²

10. A P-N junction diode under forward bias acts like:
    (a) An open switch
    (b) A closed switch
    (c) A high resistor
    (d) A capacitor

Answers to MCQs:

1. (b) 2C [C' = Kε₀A/(2d) = (4)ε₀A/(2d) = 2(ε₀A/d) = 2C]
2. (c) Not change [Condition for balance remains the same]
3. (c) Zero [Magnetic field inside solenoid is parallel to axis, velocity is parallel to field, so F = qvBsin0° = 0]
4. (a) Lags behind the voltage by π/2
5. (d) Gamma rays [Highest frequency in EM spectrum]
6. (b) β/μ [Wavelength changes to λ/μ, fringe width β = λD/d, so β' = (λ/μ)D/d = β/μ]
7. (a) 2.0 eV [Energy of photon E = hc/λ = 12400 eV Å / 2000 Å = 6.2 eV. KE_max = E - Work function = 6.2 eV - 4.2 eV = 2.0 eV]
8. (a) 3:4 [R ∝ A^(1/3), so R₁/R₂ = (A₁/A₂)^(1/3) = (27/64)^(1/3) = 3/4]
9. (b) n² [r_n ∝ n²/Z]
10. (b) A closed switch [Offers very low resistance in forward bias]

Treat this Chapter 17 Exemplar paper seriously. Solve it honestly, analyze your performance, and refine your preparation strategy accordingly. Good luck!