CBSE Class 12 Physics Question Bank with Important Questions – Ray Optics Mirror & Lens Formula 2026
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The CBSE Class 12 Physics Question Bank is an essential resource for students aiming to excel in the 2026 board examinations. Among the various units in the syllabus, Optics holds the highest weightage, typically accounting for 14 marks. Within this unit, Chapter 9: Ray Optics and Optical Instruments is a cornerstone for both theory and numerical-based scoring.
Understanding the behavior of light through mirrors and lenses is not just a requirement for clearing boards; it is a fundamental pillar for competitive exams like NEET and JEE. In 2026, the evaluation pattern emphasizes "Competency-Based Questions," which test your ability to apply the Mirror and Lens Formula to real-world scenarios, particularly in medical imaging and vision correction.
Analysis of Ray Optics in CBSE Board Exams
Based on an analysis of the last five years of CBSE previous year papers (2021–2025), Ray Optics consistently features in the 5-mark long-answer section and the 4-mark case-study section. For the 2026 session, students should expect a mix of conceptual derivations and tricky numerical problems.
Marking Distribution for Unit VI: Optics
Section | Type of Question | Marks Allotted |
Section A | MCQs & Assertion-Reasoning | 1 - 2 Marks |
Section B/C | Short Answer (Numericals) | 2 - 3 Marks |
Section D | Case Study (Application Based) | 4 Marks |
Section E | Long Answer (Derivations) | 5 Marks |
Core Concepts: Mirror and Lens Formula
The strength of your preparation in Ray Optics depends on your command over the core mathematical relationships. While the CBSE Class 12 Physics Question Bank provides numerous problems, you must first be comfortable with the following terminology and sign conventions.
1. Spherical Mirrors
Reflective surfaces are divided into concave and convex mirrors. The primary relationship used to determine image position is the Mirror Formula.
Key Identification: Concave mirrors are converging, while convex mirrors are diverging.
Critical Sign Convention: According to the Cartesian sign convention, distances measured in the direction of incident light are positive.
2. Refraction and Lenses
Lenses utilize the property of refraction to converge or diverge light. The Lens Formula is the primary tool for solving problems related to thin lenses.
Lens Maker’s Formula: Used by manufacturers to design lenses of specific focal lengths by choosing appropriate radii of curvature and materials.
Power of a Lens: Expresses the degree of convergence or divergence. In medical applications, this is measured in Dioptres (D).
Important Formulas in Ray Optics
To solve the CBSE Class 12 Physics Question Bank effectively, you should memorize these essential formula names and their applications:
Relation between Focal Length and Radius of Curvature
Mirror Formula
Linear Magnification for Mirrors
Snell’s Law of Refraction
Refractive Index and Speed of Light Relation
Lens Maker’s Formula
Thin Lens Formula
Linear Magnification for Lenses
Power of a Lens
Combination of Thin Lenses in Contact
Refractive Index of a Prism (Minimum Deviation)
Ray Optics Important Questions 2026
To rank high in your class and perform well in the board exam, focus on these high-yield questions curated from official sample papers and previous year trends.
Short Answer Type (2-3 Marks)
Numerical: An object is placed 15 cm in front of a concave mirror of focal length 10 cm. Find the nature and position of the image.
Conceptual: Why does a diamond sparkle more than a glass piece of the same shape? (Hint: Total Internal Reflection).
Application: A person uses a lens of power -2.0 D. Identify the type of defect and the nature of the lens.
Long Answer Type (5 Marks)
Derivation: Derive the Lens Maker’s Formula for a double convex lens.
Optical Instruments: Draw a neat labeled ray diagram of a Compound Microscope when the final image is formed at the least distance of distinct vision. Derive the expression for its total magnification.
Prism: Show that for a thin prism, the angle of deviation depends only on the refractive index and the angle of the prism.
Medical Relevance and Real-World Application
The 2026 CBSE curriculum places a heavy emphasis on the practical application of Physics. Ray Optics is the backbone of the medical diagnostic industry.
Endoscopy: Uses the principle of Total Internal Reflection (Optical Fibers) to visualize internal organs.
Ophthalmology: The Lens Formula is used daily by optometrists to calculate the exact power needed for spectacles to correct Myopia and Hypermetropia.
Microscopy: Pathological labs rely on the magnification principles of compound microscopes to identify pathogens.
Official Resources and Links
CBSE Official Academic Portal: cbseacademic.nic.in
Official Link : https://www.cbse.gov.in/cbsenew/question_bank.html
CBSE Academic Question Bank: Official CBSE Class 12 Materials
CBSE Academic Official Site: CBSE Academic
Conclusion
Mastering Ray Optics requires a blend of clear conceptual understanding and rigorous numerical practice. By focusing on the Mirror and Lens Formula and practicing the important questions listed in this guide, you are well on your way to securing a top score in the 2026 boards. Remember, the key to Physics is not rote learning but understanding how light interacts with the world around us.
FAQ Section
Q1: What is the most important topic in the CBSE Class 12 Physics Question Bank for Ray Optics?
A1: The most frequent topics include the Lens Maker's Formula, Total Internal Reflection, and ray diagrams for Optical Instruments like the telescope and microscope.
Q2: How do I avoid mistakes with the Mirror and Lens Formula?
A2: Always follow the New Cartesian Sign Convention. Remember that the focal length of a concave mirror/lens is always negative, while for a convex mirror/lens, it is positive.
Q3: Is the 2026 syllabus different from previous years?
A3: While the core concepts remain the same, the 2026 exam will feature more "Case-Study" and "Assertion-Reason" questions. Practicing from an updated CBSE Class 12 Physics Question Bank is crucial.
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