---
title: "NCERT Solutions Class 8 Science Ch 10 Light: Mirrors and Lenses"
url: https://www.swavid.com/science/class/8/chapter/light-mirrors-and-lenses/ncert-solutions
dateModified: 2026-10-07T16:16:49+00:00
---

# NCERT Solutions Class 8 Science Ch 10 Light: Mirrors and Lenses

This chapter explores the fundamental principles of light, focusing on reflection by spherical mirrors and refraction through lenses. It includes various hands-on activities, conceptual inquiries, and end-of-chapter exercises to test understanding of image formation and the laws of physics.

Free PDF (7 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-8/swavid-ncert-solutions-class-8-science-chapter-10-light-mirrors-and-lenses-78e52bd830.pdf

## Probe and ponder

### Question 1

*2 marks · Very short answer*

Can we make mirrors which can give enlarged or diminished images?

**Solution**

1. Yes, we can make mirrors that give enlarged or diminished images by using spherical mirrors.
2. A concave mirror can form enlarged or diminished images depending on the distance of the object, while a convex mirror always forms a diminished image.

**Answer:** Yes, we can make mirrors like concave and convex mirrors that give enlarged or diminished images.

> Common mistake: Stating that only plane mirrors exist or confusing concave and convex mirror image sizes.

### Question 2

*2 marks · Very short answer*

On 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?

**Solution**

1. Side-view mirrors of vehicles are convex mirrors which always form diminished and erect images.
2. Because the image is smaller than the actual vehicle, it appears to be farther away than it actually is, so the warning alerts drivers to the true distance.

**Answer:** The warning is written because convex mirrors form smaller images, making vehicles behind appear farther away than they actually are.

> Common mistake: Thinking the warning means objects are further away rather than closer.

### Question 3

*2 marks · Very short answer*

Why is there a curved line on some reading glasses?

**Solution**

1. The curved line on some reading glasses indicates a bifocal lens.
2. It is a combination of two types of lenses that helps a person see both distant and nearby objects clearly.

**Answer:** The curved line indicates a bifocal lens used to see both distant and nearby objects clearly.

> Common mistake: Thinking the curved line is a crack or a defect in the glass.

## Keep the curiosity alive

### Question 1

*1 mark · MCQ*

A light ray is incident on a mirror and gets reflected by it (Fig. 10.21). The angle made by the incident ray with the normal to the mirror is $40^\circ$. What is the angle made by the reflected ray with the mirror?

- 40°
- 50°
- 45°
- 60°

**Solution**

1. According to the law of reflection, the angle of incidence ($i$) is equal to the angle of reflection ($r$).
2. Since the angle of incidence is $40^\circ$, the angle of reflection is also $40^\circ$, meaning the reflected ray makes an angle of $90^\circ - 40^\circ = 50^\circ$ with the mirror surface.

**Answer:** (ii) 50°

> Common mistake: Confusing the angle made with the normal with the angle made with the mirror surface.

### Question 2

*3 marks · Short answer*

Fig. 10.22 shows three different situations where a light ray falls on a mirror: (i) The light ray falls along the normal. (ii) The mirror is tilted, but the light ray still falls along the normal to the tilted surface. (iii) The mirror is tilted, and the light ray falls at an angle of $20^\circ$ from the normal. Draw the reflected ray in each case (Use a ruler and protractor for accurate drawing). What is the angle of reflection in each case?

**Solution**

1. For case (i), the light ray falls along the normal, so the angle of incidence is $0^\circ$, making the angle of reflection $0^\circ$.
2. For case (ii), the ray still falls along the normal to the tilted surface, so the angle of incidence is $0^\circ$ and the angle of reflection is $0^\circ$.
3. For case (iii), the ray falls at an angle of $20^\circ$ from the normal, so by the law of reflection, the angle of reflection is also $20^\circ$.

**Answer:** The angles of reflection are $0^\circ$, $0^\circ$, and $20^\circ$ for cases (i), (ii), and (iii) respectively.

> Common mistake: Taking the angle with the mirror surface instead of the angle with the normal.

### Question 3

*3 marks · Short answer*

In Fig. 10.23, the cap of a sketch pen is placed in front of three types of mirrors. Match each image with the correct mirror.

**Solution**

1. Observe the size and orientation of the pen cap in the three mirrors shown in Fig. 10.23.
2. Image (i) is of the same size as the object, so it is formed by a plane mirror.
3. Image (ii) is erect and diminished in size (convex mirror), and image (iii) is enlarged and erect at close distance (concave mirror).

**Answer:** (i) Plane mirror, (ii) Convex mirror, (iii) Concave mirror

> Common mistake: Mixing up concave and convex mirror images.

### Question 4

*3 marks · Short answer*

In Fig. 10.24, the cap of a sketch pen is placed behind a convex lens, a concave lens, and a flat transparent glass piece — all at the same distance. Match each image with the correct type of lens or glass.

**Solution**

1. Examine the size of the pen cap seen through the three optical devices in Fig. 10.24.
2. Image (i) shows the object of the same size, which is formed by a flat transparent glass piece.
3. Image (ii) shows an enlarged image (convex lens) and image (iii) shows a diminished image (concave lens).

**Answer:** (i) Flat transparent glass piece, (ii) Convex lens, (iii) Concave lens

> Common mistake: Confusing convex and concave lens image sizes.

### Question 5

*1 mark · MCQ*

When the light is incident along the normal on the mirror, which of the following statements is true:

- Angle of incidence is 90°
- Angle of incidence is 0°
- Angle of reflection is 90°
- No reflection of light takes place in this case

**Solution**

1. When a light ray is incident along the normal to the mirror, it retraces its path.
2. The angle between the incident ray and the normal is $0^\circ$, so the angle of incidence is $0^\circ$.

**Answer:** (ii) Angle of incidence is 0°

> Common mistake: Writing the angle of incidence as $90^\circ$ by confusing the mirror surface with the normal.

### Question 6

*3 marks · Short answer*

Three mirrors—plane, concave and convex are placed in Fig. 10.25. On the basis of the images of the graph sheet formed in the mirrors, identify the mirrors and write their names above the mirrors.

**Solution**

1. Examine the grid lines of the graph sheet seen through each mirror in Fig. 10.25.
2. The first mirror shows grid squares of the same size, indicating a plane mirror.
3. The second mirror shows diminished squares (convex mirror), and the third mirror shows enlarged squares (concave mirror).

**Answer:** From left to right: Plane mirror, Convex mirror, Concave mirror

> Common mistake: Swapping convex and concave mirror identifications based on grid distortion.

### Question 7

*1 mark · MCQ*

In a museum, a woman walks towards a large concave mirror (Fig. 10.26). She will see that:

- her erect image keeps decreasing in size.
- her inverted image keeps decreasing in size.
- her inverted image keeps increasing in size and eventually it becomes erect and magnified.
- her erect image keeps increasing in size.

**Solution**

1. When an object is placed far away from a concave mirror, the image formed is inverted and real.
2. As the woman walks towards the concave mirror from a distance, her inverted image keeps increasing in size until it becomes extremely large.
3. When she gets very close to the mirror, the image becomes erect and magnified, which matches option (iii).

**Answer:** (iii) her inverted image keeps increasing in size and eventually it becomes erect and magnified.

> Common mistake: Students often confuse the image characteristics when an object is moved from far away to very close to a concave mirror.

### Question 8

*3 marks · Short answer*

Hold a magnifying glass over text and identify the distance where you can see the text bigger than they are written. Now move it away from the text. What do you notice? Which type of lens is a magnifying glass?

**Solution**

1. A magnifying glass is a convex lens.
2. When held at a small distance from the text, it forms an erect and enlarged image.
3. As the lens is moved away from the text, the image size changes and eventually becomes inverted.

**Answer:** A magnifying glass is a convex lens. When held close to the text, it produces an erect and enlarged image. Moving it away causes the image to change size and eventually become inverted.

> Common mistake: Not mentioning that the magnifying glass is a convex lens.

### Question 9

*3 marks · Short answer*

Match the entries in Column I with those in Column II.

**Solution**

1. (i) Concave mirror matches with (a) Spherical mirror with a reflecting surface that curves inwards.
2. (ii) Convex mirror matches with (b) It forms an image which is always erect and diminished in size.
3. (iii) Convex lens matches with (c) Object placed behind it may appear inverted at some distance.
4. (iv) Concave lens matches with (d) Object placed behind it always appears diminished in size.

**Answer:** (i)-(a), (ii)-(b), (iii)-(c), (iv)-(d)

> Common mistake: Swapping the characteristics of concave and convex mirrors or lenses.

### Question 10

*1 mark · Assertion and reason*

The following question is based on Assertion/Reason. Assertion: Convex mirrors are preferred for observing the traffic behind us. Reason: Convex mirrors provide a significantly larger view area than plane mirrors. Choose the correct option:

- Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
- Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
- Assertion is correct but Reason is incorrect.
- Both Assertion and Reason are incorrect.

**Solution**

1. Convex mirrors are preferred for side-view mirrors because they provide a wider field of view.
2. The reason correctly explains that they provide a larger view area than plane mirrors.

**Answer:** (i) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

> Common mistake: Thinking plane mirrors provide a wider view than convex mirrors.

### Question 11

*1 mark · MCQ*

In Fig. 10.27, note that O stands for object, M for mirror, and I for image. Which of the following statements is true?

- Figure (a) indicates a plane mirror and Figure (b) indicates a concave mirror.
- Figure (a) indicates a convex mirror and Figure (b) indicates a concave mirror.
- Figure (a) indicates a concave mirror and Figure (b) indicates a convex mirror.
- Figure (a) indicates a plane mirror and Figure (b) indicates a convex mirror.

**Solution**

1. In figure (a), the image is the same size as the object, which is characteristic of a plane mirror.
2. In figure (b), the image is smaller than the object, which is characteristic of a convex mirror.

**Answer:** (iv) Figure (a) indicates a plane mirror and Figure (b) indicates a convex mirror.

> Common mistake: Misidentifying the mirror type based on image size.

### Question 12

*3 marks · Short answer*

Place a pencil behind a transparent glass tumbler (Fig. 10.28a). Now fill the tumbler halfway with water (Fig. 10.28b). How does the pencil appear when viewed through the water? Explain why its shape appears changed.

**Solution**

1. The water-filled glass tumbler acts like a lens due to its curved surface.
2. When light passes through the curved water surface, it undergoes refraction.
3. This refraction changes the path of light, causing the pencil to appear changed in shape or size.

**Answer:** The pencil appears changed because the water-filled glass tumbler acts as a lens. The curved surface of the water refracts the light passing through it, which alters the apparent shape and size of the object viewed through it.

> Common mistake: Attributing the change to reflection instead of refraction.

## Frequently asked questions

### How many exercises or questions are in the new NCERT book for Class 8 Science Chapter 10 for the 2026-27 session?

The chapter features a probe and ponder section with 3 very short answer questions and a keep the curiosity alive section with 12 questions. These include assertion-reason, multiple choice, and short answer formats. SwaVid's free PDF and step-by-step solutions are on this page only to help you practice all of them.

### Which topics do the questions in this chapter cover?

The questions cover laws of reflection, angle of reflection in different ray incidences, and identification of mirrors by image size or using graph sheet images. They also explore images formed by concave mirrors, lenses, glass plates, spherical mirrors, and plane mirrors, along with magnifying glasses, convex mirrors, and bifocal lenses in reading glasses.

### What is the hardest question type in this chapter and how should I approach it?

Assertion-reason questions and problems involving the identification of mirrors using graph sheet images or ray incidences are often considered the hardest. You should approach them by carefully recalling the laws of reflection and the specific characteristics of images formed by spherical mirrors. SwaVid's free PDF and step-by-step solutions are on this page only to guide you through these difficult concepts.

### How can I write answers to get full marks in Class 8 Science exams?

To get full marks, state the underlying scientific principle or law clearly before solving numerical or conceptual problems. Use proper terminology related to convex and concave mirrors or lenses in your explanations. SwaVid's free PDF and step-by-step solutions are on this page only to show you the exact answer-writing format.

### Is the free PDF for these NCERT solutions available for download?

Yes, you can easily access and download the complete material for this curriculum based on the new NCERT book. SwaVid's free PDF and step-by-step solutions are on this page only to support your preparation for the 2026-27 session.

## Related pages

- [Class 8 Science chapters](https://www.swavid.com/science/class/8)

Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student