Question Opening prompt 1
Can mirrors make images larger or smaller?
Steps only
Yes. Concave mirrors can enlarge; convex mirrors make smaller images.
Answer
Yes. Concave mirrors can enlarge; convex mirrors make smaller images.
CLASS 8 · SCIENCE · CHAPTER 10
Light: Mirrors and Lenses
Simple answers to the opening prompts, all eleven numbered chapter activities, all end questions, and the three chapter projects.
32 worked answersComplete chapter answers
32 worked answers · short steps first, explanations when you need them
Probe and Ponder
Textbook pages 152
Question Opening prompt 2
Why does a vehicle side-view mirror warn that objects are closer than they appear?
Steps only
Convex mirrors make objects look smaller and farther away.
Answer
Convex mirrors make objects look smaller and farther away.
Question Opening prompt 3
Why is there a curved line on some reading glasses?
Steps only
It can mark the boundary between two lens powers in bifocal glasses.
Answer
It can mark the boundary between two lens powers in bifocal glasses.
Question Opening prompt 4
Write one question about mirrors or lenses.
Steps only
Example: How does object distance change an image?
Answer
Example: How does object distance change an image?
Chapter Investigations
Textbook pages 153–165
Question Activity 10.1
What images do the inner and outer sides of a shiny spoon form?
Steps only
Inner side: concave. Outer side: convex.
Answer
Inner side: concave. Outer side: convex.
Question Activity 10.2
How can you tell a concave mirror from a convex mirror by looking from the side?
Steps only
Concave curves inward; convex curves outward.
Answer
Concave curves inward; convex curves outward.
Question Activity 10.3
What images do concave and convex mirrors form as an object moves away?
Steps only
Concave: image changes with distance. Convex: always erect and smaller.
Answer
Concave: image changes with distance. Convex: always erect and smaller.
Question Activity 10.4
What happens to the reflected ray when the angle of the incoming ray changes?
Steps only
Angle of incidence = angle of reflection.
Answer
Angle of incidence = angle of reflection.
Question Activity 10.5
What happens to the reflected beam when the chart paper is bent, and what does this show about reflection?
Steps only
Compare the reflected beam with the sheet flat and bent.
Answer
The rays and normal lie in one plane.
Question Activity 10.6
How do parallel rays behave after reflection from plane, concave, and convex mirrors?
Steps only
Plane: parallel; concave: converges; convex: diverges.
Answer
Plane: parallel; concave: converges; convex: diverges.
Question Activity 10.7
Why can a concave mirror make a bright spot on paper?
Steps only
It concentrates sunlight and heat. Adult supervision is essential.
Answer
It concentrates sunlight and heat. Adult supervision is essential.
Question Activity 10.8
What do you observe when you look at printed letters through a water drop resting on an oiled glass or plastic strip?
Steps only
Compare printed letters seen through the drop with nearby letters.
Answer
The drop can magnify the letters because its curved surface bends light.
Question Activity 10.9
How do convex and concave lenses change the image of an object?
Steps only
Convex: image changes with distance. Concave: always erect and smaller.
Answer
Convex: image changes with distance. Concave: always erect and smaller.
Question Activity 10.10
How does a parallel beam behave through flat glass, a convex lens, and a concave lens?
Steps only
Convex converges; concave diverges.
Answer
Convex converges; concave diverges.
Question Activity 10.11
Can a convex lens concentrate sunlight on paper?
Steps only
Yes, but only with adult supervision; never look through the lens at the Sun.
Answer
Yes, but only with adult supervision; never look through the lens at the Sun.
Keep the Curiosity Alive
Textbook pages 166–169
Question 1
A ray makes a 40° angle with the normal. What angle does the reflected ray make with the mirror?
Steps only
50°; option (ii).
Answer
50°; option (ii).
Question 2
What are the reflection angles when the ray falls along the normal, then at 0° to the normal, and finally at 20° to the normal?
Steps only
Angles: 0°, 0°, and 20°.
Answer
Angles: 0°, 0°, and 20°.
Question 3
How can the three mirror images be matched to plane, convex, and concave mirrors?
Steps only
Same-size: plane; smaller: convex; enlarged: concave.
Answer
Same-size: plane; smaller: convex; enlarged: concave.
Question 4
How can the three images be matched to flat glass, a convex lens, and a concave lens?
Steps only
Flat glass: nearly same size; convex: may enlarge; concave: smaller.
Answer
Flat glass: nearly same size; convex: may enlarge; concave: smaller.
Question 5
Which statement is true when a light ray hits a mirror along the normal?
Steps only
Option (ii): angle of incidence is 0°.
Answer
Option (ii): angle of incidence is 0°.
Question 6
How can the mirrors be identified from the graph-sheet images shown?
Steps only
Same-size grid: plane; larger grid: concave; smaller grid: convex.
Answer
Same-size grid: plane; larger grid: concave; smaller grid: convex.
Question 7
What happens to a woman’s image as she walks towards a large concave mirror?
Steps only
Option (iii): the inverted image grows, then becomes erect and magnified.
Answer
Option (iii): the inverted image grows, then becomes erect and magnified.
Question 8
What happens when a magnifying glass is moved farther from text, and what lens is it?
Steps only
It is convex; close text looks larger, and farther away the image may invert.
Answer
It is convex; close text looks larger, and farther away the image may invert.
Question 9
Match concave mirror, convex mirror, convex lens, and concave lens to their descriptions.
Steps only
Concave mirror–a; convex mirror–b; convex lens–c; concave lens–d.
Answer
Concave mirror–a; convex mirror–b; convex lens–c; concave lens–d.
Question 10
Are the assertion and reason about convex mirrors correct?
Steps only
Option (i): both are correct, and the reason explains the assertion.
Answer
Option (i): both are correct, and the reason explains the assertion.
Question 11
How can you identify the mirrors in diagrams showing object (O), mirror (M), and image (I)?
Steps only
Option (iv): (a) plane mirror; (b) convex mirror.
Answer
Option (iv): (a) plane mirror; (b) convex mirror.
Question Question-making activity
Write questions using why, when, how long, where, and why not about mirrors and lenses.
Steps only
Answers vary; ask clear, safe questions about images and light.
Answer
Answers vary; ask clear, safe questions about images and light.
Question 12
Why does a pencil look changed when viewed through a tumbler partly filled with water?
Steps only
The curved water and glass refract light, making the pencil appear shifted or bent.
Answer
The curved water and glass refract light, making the pencil appear shifted or bent.
Question Reflection activity
How should you answer questions framed by classmates?
Steps only
Answers vary; support each answer with a clear science reason.
Answer
Answers vary; support each answer with a clear science reason.
Discover, Design, and Debate
Textbook pages 169
Question Project 1
What kind of mirror is used by a dentist or an ENT specialist, and how can you find out?
Steps only
A concave mirror can enlarge a nearby tooth; check the actual instrument with a professional.
Answer
A concave mirror can enlarge a nearby tooth; check the actual instrument with a professional.
Question Project 2
What could a simple solar cooker design include?
Steps only
Use a reflector to heat a covered dark pot; include budget and adult-supervised safety.
Answer
Use a reflector to heat a covered dark pot; include budget and adult-supervised safety.
Question Project 3
How can a simulation help investigate mirrors and lenses?
Steps only
Change object distance and record how image size and direction change.
Answer
Change object distance and record how image size and direction change.