Class 7 Science Chapter 11 Light: Shadows and Reflections

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Class 7 → Science → Chapter 11: Light – Shadows and Reflections

I. Chapter Summary:

The chapter Light: Shadows and Reflections explains the basic properties of light and how it interacts with objects. It covers how shadows are formed, types of objects based on light transmission, and how light travels in a straight line. The chapter also introduces reflection of light, mirrors, and images. Students learn how light helps us see objects and understand everyday phenomena like shadows, reflections, and visibility.

II. Key Concepts Covered:

1. Light as a Form of Energy

Light enables us to see objects and travels in a straight line.

2. Luminous and Non-Luminous Objects

  • Luminous: Objects that emit their own light (e.g., Sun, bulb)
  • Non-luminous: Objects that reflect light (e.g., moon, book)

3. Transparent, Translucent, and Opaque Objects

  • Transparent: Allow light to pass through (glass)
  • Translucent: Allow partial light (butter paper)
  • Opaque: Do not allow light (wood)

4. Formation of Shadows

Shadows are formed when an opaque object blocks light.

5. Characteristics of Shadows

  • Same shape as object
  • Formed on a surface
  • Depend on position of light source

6. Reflection of Light

When light bounces back from a surface.

7. Mirrors and Images

  • Plane mirror forms virtual and erect images
  • Image is same size as object

8. Laws of Reflection (Basic Idea)

  • Angle of incidence = Angle of reflection
  • Incident ray, reflected ray, and normal lie in same plane

III. Important Questions:

(A) MCQs (1 Mark):

  1. Which object allows light to pass completely?
    (a) Wood
    (b) Glass ✅
    (c) Cardboard
    (d) Metal
  2. A shadow is formed when light is blocked by:
    (a) Transparent object
    (b) Opaque object ✅
    (c) Translucent object
    (d) Mirror
  3. Which of the following is a luminous object?
    (a) Moon
    (b) Book
    (c) Sun ✅
    (d) Chair
  4. Reflection of light occurs when light:
    (a) Is absorbed
    (b) Passes through
    (c) Bounces back ✅
    (d) Disappears

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

  1. What is light? Why is it important?
  2. Define transparent, translucent, and opaque objects with examples.
  3. How are shadows formed?
  4. What is reflection of light?

(C) Long Answer Questions (5 Marks):

  1. Explain the formation of shadows and factors affecting them.
  2. Describe the types of objects based on transmission of light.
  3. Explain reflection of light with examples.
  4. Describe image formation in a plane mirror.

(D) HOTS Questions:

  1. Why can we see objects that do not produce their own light?
  2. Why does the size of a shadow change during the day?

IV. Key Formulas/Concepts:

  • Light travels in a straight line
  • Reflection Law: Angle of incidence = Angle of reflection

Example:
When you stand in front of a mirror, the image formed is upright and same in size.

V. Deleted Portions (CBSE 2025–2026):

No portions have been deleted from this chapter as per the rationalized NCERT textbooks.

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

Unit/Chapter Estimated Marks Type of Questions Typically Asked
Light: Shadows and Reflections 5–7 Marks MCQs, Short Answer, Diagram-based

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

VII. Previous Year Questions (PYQs):

1 Mark:

  • What type of object is glass? (2019)

2/3 Marks:

  • Explain how shadows are formed. (2020)
  • Define reflection of light. (2021)

5 Marks:

  • Describe image formation in a plane mirror. (2022)

VIII. Real-World Application Examples:

  • Mirrors used in vehicles for rear view.
  • Shadows help determine time (sun dial).
  • Transparent materials used in windows.
  • Reflection used in periscopes and kaleidoscopes.

IX. Student Tips & Strategies for Success:

Time Management:

  • Revise concepts daily for 20–30 minutes.
  • Practice diagrams regularly.

Exam Preparation:

  • Learn definitions clearly.
  • Practice MCQs and diagram-based questions.

Stress Management:

  • Stay calm and revise step-by-step.
  • Take breaks during study sessions.

X. Career Guidance & Exploration:

  • Science Stream: Physics, Optics, Engineering
  • Commerce Stream: Industrial design, Lighting business
  • Arts Stream: Architecture, Visual Arts

Entrance Exams (Basic Awareness):

  • JEE (Engineering)
  • NATA (Architecture)

XI. Important Notes:

  • Always study from NCERT textbook.
  • Practice diagrams of shadow formation and mirrors.
  • Focus on understanding concepts rather than rote learning.
  • Revise regularly for better retention.
  • Check CBSE official website for updates.

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