Class 10 → Science → Chapter: Light – Mirrors and Lenses (New Course)

I. Chapter Summary

This chapter explains the behavior of light when it reflects from mirrors and refracts through lenses. It covers laws of reflection, types of mirrors (plane, concave, convex), image formation, ray diagrams, and applications. It also introduces refraction, spherical lenses, image formation by lenses, magnification, and real-life uses such as in spectacles, cameras, and telescopes.

II. Key Concepts Covered

1. Reflection of Light

• Light bounces back from a surface.
• Laws of reflection:
  • Angle of incidence = Angle of reflection
  • Incident ray, reflected ray, and normal lie in same plane

2. Types of Mirrors

• Plane Mirror: Forms virtual, erect, same-size image
• Concave Mirror: Can form real or virtual images
• Convex Mirror: Always forms virtual, diminished image

3. Important Terms

• Pole (P), Principal Axis, Focus (F), Centre of Curvature (C)

4. Image Formation by Mirrors

• Depends on object position
• Ray diagrams used to determine image nature

5. Mirror Formula & Magnification

• Relation between object distance, image distance, and focal length
• Magnification tells size and nature of image

6. Refraction of Light

• Bending of light when passing from one medium to another

7. Spherical Lenses

• Convex Lens: Converging lens
• Concave Lens: Diverging lens

8. Image Formation by Lenses

• Different positions give real/virtual images

9. Power of Lens

• Ability of lens to converge/diverge light

III. Important Questions

(A) MCQs (1 Mark)

1. The image formed by a convex mirror is always:
   • (a) Real
   • (b) Virtual and erect ✅
   • (c) Inverted
   • (d) Same size
2. A concave mirror produces real image when object is:
   • (a) At focus
   • (b) Beyond focus ✅
   • (c) Between pole and focus
   • (d) At infinity
3. The SI unit of power of lens is:
   • (a) Meter
   • (b) Dioptre ✅
   • (c) Watt
   • (d) Newton
4. Refraction occurs due to change in:
   • (a) Speed of light ✅
   • (b) Direction only
   • (c) Color
   • (d) Frequency

(B) Short Answer Questions (2/3 Marks)

1. State the laws of reflection.
2. Differentiate between concave and convex mirrors.
3. What is magnification? How is it calculated?
4. Explain refraction with an example.

(C) Long Answer Questions (5 Marks)

1. Explain image formation by concave mirror with ray diagrams.
2. Describe image formation by convex lens for different object positions.
3. Derive mirror formula and explain sign convention.
4. Explain applications of spherical mirrors and lenses in daily life.

(D) HOTS Questions

1. Why are convex mirrors used as rear-view mirrors in vehicles?
2. A student places an object at focus of a concave mirror. What will happen to the image? Explain logically.

IV. Key Formulas / Concepts

• Mirror Formula:

$\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$​

• Magnification (Mirror):

$m = \frac{h_i}{h_o} = \frac{v}{u}$​

• Lens Formula:

$\frac{1}{f} = \frac{1}{v} – \frac{1}{u}$​

• Magnification (Lens):

$m = \frac{v}{u}$​

• Power of Lens:

$P = \frac{1}{f \, (\text{in meter})}$​

V. Deleted Portions (CBSE 2025–2026)

• Some detailed ray diagram derivations
• Numerical complexity reduced
• Advanced conceptual derivations removed

(Refer NCERT official website for latest updates)

VI. Chapter-Wise Marks Bifurcation (Estimated – CBSE 2025–2026)

Note: This is an estimate. Actual marks may vary.

VII. Previous Year Questions (PYQs)

1 Mark

• Define power of lens. (2020)

2/3 Marks

• State laws of reflection. (2019)
• Define magnification. (2021)

5 Marks

• Draw ray diagrams for concave mirror. (2018)
• Explain refraction through convex lens. (2022)

VIII. Real-World Application Examples

• Rear-view mirrors in vehicles → Convex mirrors
• Shaving mirrors → Concave mirrors
• Spectacles → Lenses
• Cameras & telescopes → Lens systems
• Solar cookers → Concave mirrors

IX. Student Tips & Strategies for Success

Time Management

• Allocate time for numericals and diagrams
• Practice daily for better understanding

Exam Preparation

• Focus on ray diagrams and formulas
• Practice previous year questions

Stress Management

• Take short breaks
• Revise regularly instead of last-minute study

X. Career Guidance & Exploration (Class 10)

Streams After Class 10

• Science → Engineering, Medical, Research
• Commerce → Business, CA, Finance
• Arts → Civil services, Law, Humanities

Relevant Exams

• NTSE
• Olympiads
• Foundation for JEE/NEET

XI. Important Notes

• Always follow NCERT textbook first
• Practice ray diagrams regularly
• Learn formulas with proper understanding
• Refer CBSE official website for updates
• Concept clarity is more important than rote learning