Light NCERT Solutions – Class 7 Science

Class 7 is one of the most important initial academic phases of secondary education. Class 7 students are introduced to several new topics and chapters in each subject allotted to their syllabus. The pupils become aware of the secondary educational structure and board examination patterns. Chapter 15 of the Class 7 Science syllabus is about light. The students will learn about the more complex science concepts  through this chapter. NCERT Solutions for Class 7 Science Chapter 15 by Extramarks are clear and concise solutions to the questions given in this chapter. Students can use these to prepare more effectively and for cross-referencing any question that they are not able to answer.

NCERT Solutions for Class 7 Science Chapter 15 

Access NCERT Solutions for Class 7 Science Chapter 15 – Light

NCERT Solutions for Class 7 Science Chapter 15 

This chapter teaches students the concepts of light, its various principles, its reflection, and other aspects. The chapter comprises six topics. Each one depicts a fundamental principle of light. The chapter begins with an introduction to the definition of light. Then, the chapter proceeds to the crucial concept of how light can travel through a straight line. The chapter also explains how the reflection of light works and how images are created through lenses. 

A list of sub-sections included in the chapter is given below:

15.0: Light

15.1: Light Travels along a Straight Line

15.2: Reflection of Light

15.3: Right or Left!

15.4: Playing with Spherical Mirrors

15.5: Images formed by Lenses

15.6: Sunlight – White or Coloured?

NCERT Class 7 Science Chapter 15 Light Topic-Wise Discussion 

Class 7 Science Chapter 15 Solutions consists of seven subtopics. We present a detailed discussion of each topic.

Introduction 

Class 7  Chapter 15 begins with an introduction to light and how we see the properties of light in our daily life. The introduction section offers a brief idea of the chapter and talks about the properties of light that the students will learn in the chapter.

Light Travels along a Straight Line

In this section, the students learn about one of the most crucial features of light that light always travels through a straight line. The section reminds the students about an experiment they tried in Class 6 . In  the experiment, they had a straight pipe, a bent pipe, and a candle. The students viewed the candlelight using both the straight and the bent pipe. In doing so, they observed that light can only be seen through a straight pipe, which implies that light travels along straight lines. 

Reflection of Light

In this section, students get to know that there is one way to change the direction of light. This can be done by letting the light fall on a shiny surface. The Class 7 Science Chapter 15 Solutions present different activities to make the students understand the concept better. One such example is when students keep a candle in front of a mirror to observe the different reflections of the flame when the candle is moved around.

Right or Left

The section teaches the  Class 7 students about lateral inversion. The science chapter refers to the phenomenon of mirror images. A left-handed person looks right-handed while standing in front of a mirror and vice-versa. For this reason, the word Ambulance is written in reverse. The mirror view helps the drivers of other vehicles to read the word through their rear-view mirrors and give it a clear passage to move. 

Playing with Spherical Mirror

The topic in  Chapter 15 of  Class 7 Science helps the students learn the concepts of real and virtual images. This chapter also arranges some activities to help the students understand the topic with real-life lessons. The  Class 7 students can perform an easy experiment to see the features of a spherical mirror by merely using a spoon. The students can see their reflection through it and find the image to be erected. The inner surface of a spoon acts as a concave mirror whereas the outer one acts as a convex mirror. 

Image Formed by Lenses

This section of the  Class 7 science syllabus teaches the students to learn about different types of lenses. The chapter describes the properties of various lenses and their uses. The chapter also encourages the students to do some home experiments and explore the effects of multiple lenses. 

Sunlight – White or Coloured 

The last section of  Chapter 15 focuses on whether sunlight is white or colourful. The activities in this section instruct the students to look at rainbows and soap bubbles to see the seven colours. The chapter teaches the students about white sunlight and the different colours hidden within it.

Reasons to Opt for NCERT Solutions for Class 7 Science Chapter 15

Let us have a look at some of the top reasons students should refer to NCERT Solutions by Extramarks.

  • The solutions have been designed based on the CBSE syllabus and guidelines.
  • Subject-matter experts prepare and draft the solutions to impart accurate information and elaborate explanations to the students.
  • The solutions are descriptive yet crisp.
  • The students can access the solutions online and study them anytime, at their convenience.
  • The real-life examples in the solutions help the students understand the topics with better clarity.
  • The language used in the solutions is simple and easy to understand. 

Q.1 Fill in the blanks:
(a) An image that cannot be obtained on a screen is called____________.
(b) Image formed by a convex __________ is always virtual and smaller in size.
(c) An image formed by a __________ mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a _________ image.
(e) An image formed by a concave ___________ cannot be obtained on a screen.

Ans-

(a) An image that cannot be obtained on a screen is called virtual image.
(b) Image formed by a convex mirror is always virtual and smaller in size.
(c) An image formed by a plane mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a real image.
(e) An image formed by a concave lens cannot be obtained on a screen.

Q.2 Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) We can obtain an enlarged and erect image by a convex mirror. (T/F)
(b) A concave lens always form a virtual image. (T/F)
(c) We can obtain a real, enlarged and inverted image by a concave mirror. (T/F)
(d) A real image cannot be obtained on a screen. (T/F)
(e) A concave mirror always form a real image. (T/F)

Ans-

(a) False

(b) True

(c) True

(d) False

(e) False

Q.3 Match the items given in Column I with one or more items of Column II.

Column I Column II
A plane mirror Used as a magnifying glass
A convex mirror Can form image of objects spread over a large area
A convex lens Used by dentists to see enlarged image of teeth
A concave mirror The images is always inverted and magnified
A concave lens The images is erect and of the same size as the object
The image is erect and smaller in size than the object

Ans-

The correctly matched contents of Column I and Column II are as follows:

Column I Column II
A plane mirror The images is erect and of the same size as the object
A convex mirror Can form image of objects spread over a large area
A convex lens Used as a magnifying glass
A concave mirror The images is always inverted and magnified

Used by dentists to see enlarged image of teeth
A concave lens The image is erect and smaller in size than the object

 

Q.4 State the characteristics of the image formed by a plane mirror.

Ans-

The characteristics of the image formed by a plane mirror are as follows:

1. Image is erect and virtual.
2. Image is formed at the same distance behind the mirror as the object is placed in front of the mirror.
3. Image is of the same size as that of the object.
4. Image is laterally inverted.

Q.5 Find out the letters of English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.

Ans-

The letters of English alphabets, whose image formed by the plane mirror is exactly like the letter itself, are as follows:

A, H, I, M, O, T, U, V, W, X and Y

All of these letters can be divided into two equal halves through a vertical plane. Therefore, even their images after undergoing lateral inversion would appear same as that of letter itself. Thus, we can say that all vertically symmetrical objects will produce image same as themselves when placed in front of a plane mirror.

Q.6 What is a virtual image? Give one situation where a virtual image is formed.

Ans-
The image which cannot be obtained on a screen is called a virtual image. When we see ourselves in a plane mirror, the image formed cannot be obtained on a screen. It is one of the situations where a virtual image is formed.

Q.7 State two differences between a convex and a concave lens.

Ans-

The two differences between a convex and a concave lens are as follows:

1. A convex lens forms a real and inverted image while a concave lens forms a virtual and erect image.
2. A convex lens can also form a virtual and erect image when object is placed very close to it whereas, a concave lens cannot form a real and inverted image at all.

Q.8 Give one use each of a concave and a convex mirror.

Ans-

Use of concave mirror:
As concave mirror produces large magnified image, it is used by the doctors to examine eye, ears, nose and throat etc.

Use of convex mirror:
Convex mirror forms small and virtual image due to which it is used as the side rear view mirror in vehicles to see the large area for a better view of traffic on road.

Q.9 Which type of mirror can form a real image?

Ans-
Concave mirror can form a real image.

Q.10 Which type of lens forms always a virtual image?

Ans-
Concave lens always forms a virtual image.

Q.11 A virtual image larger than the object can be produced by a
(i) concave lens
(ii) concave mirror
(iii) convex mirror
(iv) plane mirror

Ans-
Correct option is (ii).
Explanation:
When the object is placed very close to the concave mirror, the image formed is virtual, erect and magnified.

Q.12 David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be
(i) 3 m
(ii) 5 m
(iii) 6 m
(iv) 8 m

Ans-
Correct option is (iii).
Explanation:
Distance between the mirror and David’s image = 4 m
If David moves 1 m towards the mirror, then his distance from the mirror = 4 m − 1 m = 3 m
Therefore, the distance between David and his image = 3 m + 3 m = 6 m

Q.13 The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear view mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be
(i) 1 m/s
(ii) 2 m/s
(iii) 4 m/s
(iv) 8 m/s

Ans-
Correct option is (iii).
Explanation:
Speed of truck in the mirror = 2v
where v is original speed.
Speed of truck in the mirror = 2 × 2 m/s = 4 m/s

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FAQs (Frequently Asked Questions)

You can find the chapter-wise solutions of Class 7, Chapter 15 of the Science syllabus on Extramark’s website or the app.

The core concept of Class 7 Science  Chapter 15 is various concepts related to light like its reflection, formation of images through lenses, spherical mirrors, etc.