Introduction
Preparing for Class 10 Physics CBSE board exams requires a smart strategy rather than just memorizing concepts. Based on expert guidance and analysis of previous years’ question patterns, focusing on high-weightage topics, important numericals, and conceptual clarity can significantly boost your score. This guide covers 33 important questions along with key concepts from major chapters like Light, Human Eye, Electricity, and Magnetic Effects of Electric Current.
To fully understand the concepts, detailed explanations, and step-by-step solving of all 33 important questions, make sure to watch the complete video. It will help you build deeper conceptual clarity and perform better in your board exams.
Most Important Topics for Class 10 Physics Boards
Light: Reflection and Refraction
- Laws of reflection and refraction
- Ray diagrams and image formation
- Nature, position, and size of images
- Formula-based numericals with correct SI units
Human Eye and Defects of Vision
- Myopia, Hypermetropia, Presbyopia
- Causes and corrections using lenses
- Ray diagrams for defects and their correction
- Near point and far point numericals
Electricity
- Ohm’s Law and V-I graphs
- Series and parallel combination of resistors
- Electrical power and energy
- Circuit diagrams and practical applications
Magnetic Effects of Electric Current
- Right-hand thumb rule
- Fleming’s left-hand rule
- Solenoid and magnetic field
- Factors affecting magnetic field
33 Most Important Questions Are
Light: Reflection, Refraction & Lenses
Q1. Convex mirror (R = 3 m), object at 5 m. Find image.
Answer: Image is virtual, erect, and diminished, formed behind the mirror.
Explanation: Convex mirrors always form virtual and diminished images. Using mirror formula (f = R/2 = +1.5 m, u = -5 m), image forms between pole and focus.
Q2. Object at 30 cm, m = 1/2. New position for m = 1/3?
Answer: First find focal length using m = v/u and mirror/lens formula, then use it to calculate new object distance.
Explanation: This is a two-step numerical. First case gives focal length, second case uses same focal length to find new u.
Q3. Object moves to focus of convex lens.
Answer: Image forms at infinity and is highly enlarged.
Explanation: When object is at focus of convex lens, refracted rays become parallel.
Q4. Object near convex mirror (f = 15 cm).
Answer: Image is virtual, erect, and diminished.
Explanation: Convex mirror always gives virtual images. As object moves away, image size decreases and shifts towards focus.
Q5. Boy moves towards concave mirror.
Answer: Image position changes depending on object position relative to F and C.
Explanation: For concave mirror, image nature changes from real to virtual when object crosses focus.
Q6. Refractive index of diamond.
Answer: n(diamond/air) = n(diamond/glass) × n(glass/air).
Explanation: Relative refractive indices multiply to give absolute refractive index.
Q7. Convex lens (image same size).
Answer: Object is placed at 2F and image is also formed at 2F.
Explanation: For convex lens, equal size image forms only when object is at 2F. Hence f = v/2.
Q8. Concave mirror (f = 15 cm).
Answer: Image is real, inverted, and size depends on object position.
Explanation: Use mirror formula and magnification (m = -v/u) to find nature and size.
Q9. Speed of light in glass.
Answer: v = c/n = 3×10⁸ / 1.5 = 2×10⁸ m/s.
Explanation: Refractive index formula n = c/v.
Q10. Mirror forming erect diminished image.
Answer: Convex mirror.
Explanation: Only convex mirror always forms erect and diminished images for all object positions.
Human Eye and Defects
Q11. Identify defect from diagram.
Answer: Myopia or Hypermetropia depending on image position.
Explanation: If image forms before retina → myopia; behind retina → hypermetropia.
Q12. Cannot see near objects.
Answer: Hypermetropia.
Explanation: Image forms behind retina; corrected using convex lens.
Q13. (Repeated variant)
Answer: Hypermetropia.
Explanation: Same reasoning as Q12.
Q14. Assertion–Reason.
Answer: Depends on given statements.
Explanation: Evaluate truth of assertion and reason, then check if reason explains assertion.
Q15. Causes of myopia & hypermetropia.
Answer: Myopia → elongated eyeball; Hypermetropia → shortened eyeball or weak lens.
Explanation: Correction uses concave lens (myopia) and convex lens (hypermetropia).
Q16. Cannot see board.
Answer: Myopia.
Explanation: Distant objects not visible; corrected using concave lens.
Q17. (Repeated variant)
Answer: Myopia.
Explanation: Same concept as Q16.
Q18. Near point = 75 cm.
Answer: Use lens formula to find focal length and power.
Explanation: Lens must form image at 25 cm (normal near point).
Q19. Twinkling of stars.
Answer: Atmospheric refraction.
Explanation: Due to continuous variation in refractive index of atmosphere.
Q20. Correcting far-sightedness.
Answer: Convex lens.
Explanation: Helps converge light rays to focus on retina.
Electricity
Q21. Resistance halved.
Answer: Heat produced becomes double.
Explanation: From H = V²t/R, if resistance decreases, heat increases (assuming constant voltage).
Q22. Wire stretched.
Answer: Resistance increases.
Explanation: R ∝ L/A; stretching increases length and decreases area.
Q23. Rs/Rp for 4 resistors.
Answer: Rs = 32Ω, Rp = 2Ω → Rs/Rp = 16.
Explanation: Series: sum; Parallel: reciprocal formula.
Q24. Circuit current.
Answer: I = V / R_eq.
Explanation: First calculate equivalent resistance, then apply Ohm’s law.
Q25. Motor (1100 W, 220 V).
Answer: I = 5 A.
Explanation: Using P = VI.
Q26. Ohm’s law circuit.
Answer: Ammeter in series, voltmeter in parallel.
Explanation: Ammeter measures current, voltmeter measures potential difference.
Concept-Based
Q27. Object moving towards lens.
Answer: Image moves away and increases in size (for convex lens before focus).
Explanation: As object approaches focal point, image distance increases.
Q28. Numerical + concept question.
Answer: Requires combining formulas and conceptual understanding.
Explanation: Tests both calculation and theory.
Q29. Diagram-based application.
Answer: Depends on ray diagram interpretation.
Explanation: Requires understanding of image formation rules.
Key Preparation Tips for Physics Boards
- Focus on high-weightage chapters and repeated questions
- Practice ray diagrams and circuit diagrams regularly
- Solve numericals step-by-step with correct sign conventions
- Revise formulas and SI units thoroughly
- Practice assertion-reason questions carefully
Common Mistakes to Avoid
- Ignoring sign conventions in numericals
- Skipping diagrams in Light and Electricity chapters
- Not practicing MCQs and assertion-reason questions
- Weak conceptual understanding of defects of vision
Smart Study Strategy for CBSE Physics
- Prioritize important topics over entire syllabus
- Practice previous year questions regularly
- Focus on conceptual clarity rather than rote learning
- Revise daily using short notes and formulas
FAQs
Q1. Which chapter is most important?
Light and Electricity are most important.
Q2. Are numericals important?
Yes, they carry high weightage.
Q3. How to improve Physics score?
Practice questions, revise concepts, and avoid mistakes.
Q4. Are diagrams important?
Yes, especially in Light and Electricity.
Conclusion
Your Physics score will depend on how well you handle concepts under pressure. These final days are not for learning new topics – they are for mastering what matters most. Focus on formulas, practice numericals repeatedly, and make sure you don’t make silly mistakes in calculations or diagrams.
If you truly want to score high, don’t just read – practice actively. Watch the complete video, understand every step, and solve alongside it. This last phase of revision can decide whether you score average marks or stand out in your board exam.
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