Question 1

Can we make mirrors that can give enlarged or diminished images? (Page 152)

Accepted Answer

Yes, we can make mirrors that produce enlarged or diminished images. Specifically, concave mirrors can form both enlarged and diminished images depending on the object’s distance from the mirror, while convex mirrors always produce diminished images.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 2

On the side-view mirrors of vehicles, there is a warning that says “Objects in mirror are closer than they appear”. Why is this warning written there? (Page 152)

Accepted Answer

The warning “Objects in mirror are closer than they appear” is written on the side-view mirrors of vehicles because these mirrors are typically convex. Convex mirrors make objects appear smaller and farther away than they are, which can lead to misjudging distances. The warning is there to alert drivers to this effect and prevent accidents caused by inaccurate distance perception.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 3

Why is there a curved line on some reading glasses? (Page 152)

Accepted Answer

The curved line on reading glasses is due to the convex shape of the lens. These lenses are thicker in the middle and thinner at the edges, causing light rays to converge (bend inward) and improve near vision for individuals with presbyopia. This curvature is essential for correcting the vision by focusing light properly on the retina.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 4

How can we distinguish between concave and convex mirrors? (Page 155)

Accepted Answer

To distinguish between concave and convex mirrors, observe how they reflect light and the images they form. Concave mirrors curve inward, causing parallel light rays to converge at a focal point, and can form both real and virtual images. Convex mirrors curve outward, causing parallel light rays to diverge, and always form virtual, diminished images.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 5

We have observed images formed by three types of mirrors – plane, concave, and convex. But are there any laws that govern the image formation? (Page 157)

Accepted Answer

Yes, some laws govern image formation by mirrors, including plane, concave, and convex mirrors. These laws are based on the laws of reflection, which state that the angle of incidence (the angle at which light hits the mirror) is equal to the angle of reflection (the angle at which light bounces off the mirror). Additionally, the incident ray, the reflected ray, and the normal (an imaginary line perpendicular to the mirror’s surface at the point of incidence) all lie in the same plane.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 6

Are the laws of reflection applicable to spherical mirrors also?

Accepted Answer

Yes, the laws of reflection apply to spherical mirrors. These laws state that the angle of incidence is equal to the angle of reflection, and the incident ray, reflected ray, and normal all lie in the same plane. These laws hold for all types of reflecting surfaces, including spherical mirrors like concave and convex mirrors.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 7

What changes can be seen in the objects when viewed through lenses? (Page 163)

Accepted Answer

When an object is viewed through a lens, several changes can be observed in its image compared to the object itself. The most common changes include alterations in size, orientation, and whether the image is real or virtual. Specifically, concave lenses typically produce diminished, virtual, and upright (erect) images.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 8

Do lenses also converge or diverge the light beam? (Page 163)

Accepted Answer

Yes, lenses can both converge and diverge light beams. Convex lenses converge (focus) light, while concave lenses diverge (spread out) light.

Source: This question is from Light Mirrors and Lenses, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Light Mirrors and Lenses: Lenses, Converge, Diverge, Light, Beam, Page. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Light Mirrors and LensesQ1: Can we make mirrors that can give enlarged or diminished images? (Page 152)
Q10: Where are all the lenses used? (Page 165)
Q12: Place a pencil behind a transparent glass tumbler (Figure a). Now fill the tumbler halfway with...
Q2: On the side-view mirrors of vehicles, there is a warning that says “Objects in mirror are closer...
Q3: Why is there a curved line on some reading glasses? (Page 152)
Practice more questions from Light Mirrors and Lenses &mdash; Science, Class 8 CBSE

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 9

Since a convex lens converges a light beam, can it also burn a paper? (Page 164)

Accepted Answer

Yes. In simple terms, the convex lens acts like a magnifying glass, focusing the sun’s rays and intensifying the heat at a specific spot, which can be enough to ignite a flammable material like paper.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 10

Where are all the lenses used? (Page 165)

Accepted Answer

Lenses are used in a variety of applications, both in everyday life and in scientific instruments. These include eyeglasses, cameras, microscopes, telescopes, and projectors, as well as simple magnifying glasses and spyholes indoors.
NCERT Class 8 Science Chapter 10 Question Answer Light: Mirrors and Lenses (Exercise)
Keep the Curiosity Alive (Pages 166-169)

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 11

In the Figure, note that O stands for object, M for mirror, and I for image.
Which of the following statements is true?
(i) Figure (a) indicates a plane mirror, and Figure (b) indicates a concave mirror.
(ii) Figure (a) indicates a convex mirror and Figure (b) indicates a concave mirror.
(iii) Figure (a) indicates a concave mirror and Figure (b) indicates a convex mirror.
(iv) Figure (a) indicates a plane mirror, and Figure (b) indicates a convex mirror.

Accepted Answer

(ii) Figure (a) indicates a convex mirror and Figure (b) indicates a concave mirror.

Source: This question is from Light Mirrors and Lenses, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Light Mirrors and Lenses: Figure, Stands, Object, Mirror, Image, Statements. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Light Mirrors and LensesQ1: Can we make mirrors that can give enlarged or diminished images? (Page 152)
Q10: Where are all the lenses used? (Page 165)
Q12: Place a pencil behind a transparent glass tumbler (Figure a). Now fill the tumbler halfway with...
Q2: On the side-view mirrors of vehicles, there is a warning that says “Objects in mirror are closer...
Q3: Why is there a curved line on some reading glasses? (Page 152)
Practice more questions from Light Mirrors and Lenses &mdash; Science, Class 8 CBSE

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.

Question 12

Place a pencil behind a transparent glass tumbler (Figure a). Now fill the tumbler halfway with water (Figure b). How does the pencil appear when mewed through the water? Explain why its shape appears changed.

Accepted Answer

When we place a pencil behind a transparent glass tumbler and fill the tumbler halfway with water, the pencil will appear to be bent or broken at the point where it enters the water. The submerged portion of the pencil might also appear slightly thicker or shifted from its actual position. This phenomenon is called refraction of light.
Why it Happens
Change in medium: Light travels at different speeds in different materials (media). Air is an optically rarer medium, meaning light travels faster in it, compared to water, which is an optically denser medium where light travels more slowly.
Bending of Light (Refraction): When light rays from the pencil travel from the water (denser medium) into the air (rarer medium) and then into our eyes, their speed changes. This change in speed causes the light rays to bend or deviate from their original path. Specifically, when light goes from a denser medium to a rarer medium, it bends away from the normal (an imaginary line perpendicular to the surface at the point where light enters the new medium).
Apparent Position: Because our brains interpret light rays as traveling in straight lines, the bending of light at the water-air interface makes the submerged part of the pencil appear to be at a different location than its actual position, creating the illusion of a bent or broken pencil. The extent of this bending depends on the angle at which we view the pencil and the difference in optical density between the two media (water and air). If we view the pencil straight from above, we won’t observe the bending as the light rays would be traveling perpendicular to the surface, and refraction would be minimal.

Chapter Overview: Light
    This optics chapter covers the laws of reflection, regular vs diffused reflection, multiple images in mirrors, dispersion of white light, the human eye anatomy and function, and the Braille system for visually impaired persons. Ray diagrams and the multiple image formula are key exam topics.
    Board Exam Weightage: 5-7 marks | Difficulty: Moderate to High

Key Formulas & Concepts
  
    ConceptDetails
    
      Laws of Reflection1. Angle of incidence = Angle of reflection (i = r); 2. Incident ray, reflected ray, and normal lie in the same plane
      Multiple ImagesNumber of images in mirrors at angle θ: n = (360/θ) - 1
      VIBGYORViolet, Indigo, Blue, Green, Yellow, Orange, Red (spectrum colours)
      Lateral InversionLeft and right reversal in mirror images (AMBULANCE written reversed)

Must-Know Concepts
  
    Angles of incidence and reflection are measured from the NORMAL, not the surface
    Regular reflection (smooth surface) gives clear images; diffused reflection (rough surface) scatters light
    Diffused reflection also follows laws of reflection at each individual point
    Two parallel mirrors (0°) produce infinite images
    Kaleidoscope uses 3 mirrors to create symmetrical patterns
    White light disperses into VIBGYOR when passing through a prism
    The eye works like a camera: cornea → pupil → lens → retina → optic nerve → brain

Regular vs Diffused Reflection
  
    FeatureRegular ReflectionDiffused ReflectionSurfaceSmooth, polishedRough, unevenReflected RaysParallel (same direction)Scattered (different directions)ImageClear, well-definedNo clear imageExamplesMirror, still water, polished metalWall, paper, road, chalk, wood

Common Mistakes to Avoid
    
      Measuring angles from the surface instead of from the normal
      Thinking diffused reflection does not follow laws of reflection (it does, at each point)
      Errors in the multiple image formula (n = 360/θ - 1)
      Confusing parts and functions of the human eye

Scoring Tips
    
      Always draw the normal first when drawing ray diagrams
      Practice the formula with common angles: 90° → 3 images, 60° → 5 images
      Learn the path of light through the eye in order
      Draw and label the human eye from memory for guaranteed marks

Frequently Asked Questions
    Q: How many marks does this chapter carry in the exam?A: Approximately 5-7 marks in the annual exam.
    Q: What question types are commonly asked?A: MCQs (1 mark), Very Short Answer (2 marks), Short Answer (3 marks), and Long Answer / Diagram (5 marks).
    Q: Is this chapter important for competitive exams?A: Yes, concepts from this chapter appear in NTSE, Olympiad, and other science competitions.