NCERT Solutions Class 7 Science Chapter 11 - Light

Class 7 science chapter light presents students with fundamental ideas concerning the nature of light and how it reacts on various objects. In light class 7 NCERT, students can find information on the human eye structure and its operation, light, spectrum, and many more key concepts. 

The class 7 light NCERT solutions are comprehensive and concise to explain all the problems of the textbook so that students gain a better understanding of concepts easily. They also give illustrations and elaborate on how to solve problems to make the understanding of light to be more comprehensive. The NCERT Solutions for class 7 Science chapter 11 light question answer are built in a way that enhances accuracy and prepares learners for exams, while providing a firm conceptual framework that covers the theoretical and practical part of the chapter.

1.0Download Class 7 Science Chapter 11 NCERT Solutions PDF Online

Students can download the Class 7 Science Chapter 11 Light question and answer PDF from the table above. This is preferred because this PDF can be accessed at any time and from any place, and students can study and revise at their own preferred pace.

2.0What Will Students Learn in Chapter 11: Light?

• Students will understand how light reflects off surfaces, the laws of reflection, and the roles of the incident and reflected rays, along with the angles of incidence and reflection.
• They will explore concave and convex mirrors, learning how these mirrors form different types of images (real and virtual) depending on the object's position.
• Students will study convex and concave lenses, understanding how these lenses bend light to form images, and learn about focal length and image formation through lenses.
• The chapter provides insights into the structure of the human eye, its working, and common vision problems like nearsightedness and farsightedness, along with their correction using lenses.
• Students will discover that sunlight consists of various colors, which can be separated to form a spectrum, demonstrating the concept of white light and its components.

3.0NCERT Questions with Solutions for Class 7 Science Chapter 11 - Detailed Solutions

• Fill in the blanks (1) An image that cannot be obtained on a screen is called _____ . (2) Image formed by a convex _______ is always virtual and smaller in size. (3) An image formed by a _______ mirror is always of the same size as that of the object. (4) An image which can be obtained on a screen is called a ____ image. (5) An image formed by a concave ____ cannot be obtained on a screen. Solution (1) Virtual image (2) Mirror (3) Plane (4) Real (5) Lens
• Mark True if the statement is true and False if it is false. (1) We can obtain an enlarged and erect image by a convex mirror. (2) A concave lens always forms a virtual image. (3) We can obtain a real, enlarged and inverted image by a concave mirror. (4) A real image cannot be obtained on a screen. (5) A concave mirror always forms a real image. Solution (1) False : The image formed by a convex mirror is always virtual, diminished and erect. (2) True : The image formed by a concave lens is always virtual, erect and diminished. (3) True : The image formed by a concave mirror can be real or virtual, enlarged or diminished, and erect or inverted, depending upon the distance of the object from the mirror. (4) False : The image that can be obtained on a screen is called a real image. Virtual images cannot be obtained on a screen. (5) False : A concave mirror can form both real and virtual images. The nature of the image depends on the distance of the object from the mirror.
• Match the items given in Column I with one or more items of Column II.

Solution (a) (v) A plane mirror forms an image which is erect and of the same size as the object. (b) (ii) and (vi) A convex mirror forms a virtual, diminished, and upright image and therefore, covers a larger area of view. Its field of view is very large. (c) (i) A convex lens can form a magnified image of the object. Therefore, it is used as a magnifying glass. (d) (iii) A concave mirror forms an enlarged image of the object. Therefore, it is used to see an enlarged image of teeth by the dentist, (e) (vi) The image formed by a concave lens is always virtual, upright and erect and smaller in size than the object.

• State the characteristics of the image formed by a plane mirror. Solution The image formed by a plane mirror is erect, laterally inverted, and of the same size as that of the object. The left side of the object appears on the right side of the image. Also, the distance of the image from the plane mirror is same as the distance between the plane mirror and the object.
• 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. Solution If the letters of English alphabet A, H, I, M, O, T, U, V, W, X, Y are kept in front of a plane mirror, then they would form images which exactly look like the original letters of the alphabet. These letters are vertically symmetric. For example, if we divide letters $A$ and $U$ in the middle, then we would find that the right halves are equivalent to the left halves of the letters.

• Hence, even if the image interchanges sidewise, it will appear same as the letter.
• What is a virtual image? Give one situation where a virtual image is formed. Solution When an image cannot be obtained on a screen, it is called a virtual image. The image formed by a plane mirror is virtual, because the image cannot be obtained on a screen when placed either in front of the mirror or behind it.
• State two differences between a convex and a concave lens. Solution (i) Convex lens is thicker in the middle while concave lens is thinner in the middle.

• (ii) A convex lens converges the light ray falling on it, while a concave lens diverges the light ray falling on it.

• Give one use each of a concave and a convex mirror. Solution Concave mirrors can form enlarged image of the object. Therefore, they are used by the dentist to see the enlarged image of the patient's teeth. Convex mirror forms diminished and upright image of the object. It is used as a side view mirror of the car because it enables the driver to view objects spread over a large area behind him/her.
• Which type of mirror can form a real image? Solution A concave mirror can form real image of an object. The nature of the image depends on the distance of the object from the concave mirror.
• Which type of lens forms always a virtual image?Solution A concave lens always forms a virtual image of an object.
• A virtual image larger than the object can be produced by a (i) Concave lens (ii) Concave mirror (iii) Convex mirror (iv) Plane mirror Solution (ii) Concave mirror can form virtual and magnified image of the object. Concave lens and convex mirror forms virtual but diminished image of the object. Plane mirror forms virtual and same size image of the object.
• 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 Solution (iii) 6 m In the case of a plane mirror, the distance between the object and the mirror ( ${\mathrm{d}}_1$ ) is same as the distance between the image and the mirror ( ${\mathrm{d}}_2$ ).

• Given, Distance between the mirror and David's image, ${\mathrm{d}}_2=4\mathrm{m}$ Therefore, ${\mathrm{d}}_1={\mathrm{d}}_2=4\mathrm{m}$ If David moves 1 m towards the mirror, then ${\mathrm{d}}_1=4-1=3\mathrm{m}$ Again, ${\mathrm{d}}_1={\mathrm{d}}_2=3\mathrm{m}$ Therefore, the distance between David and his image is $d_1+d_2=3+3=6\mathbf{m}$.
• The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of $2\mathrm{m}/\mathrm{s}$. The driver sees in his rear view mirror the image of truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be (i) $1\mathrm{m}/\mathrm{s}$ (ii) $2\mathrm{m}/\mathrm{s}$ (iii) $4\mathrm{m}/\mathrm{s}$ (iv) $8\mathrm{m}/\mathrm{s}$ Solution (ii) $2\mathrm{m}/\mathrm{s}$ The reversing speed of the car is $2\mathrm{m}/\mathrm{s}$ which means the car is approaching the truck with a speed of 2 m per second as shown in the figure below. The car mirror and driver have the same reversing speed. Let, initially distance between truck and the car is ' d '. So, the driver inside the car see the virtual and erect image of truck at a distance ' d ' behind the car mirror.

• As the car moves backward by 2 m in 1 second, the distance between the car mirror and the truck reduces by 2 m (hence, the distance between car mirror and image of truck also reduces by 2 m ). Car with a plane mirror

• After 1 second So, the car driver observe the image of truck coming towards him at $2\mathbf{m}/\mathbf{s}$. (Note : The answer to this question is given $4\mathrm{m}/\mathrm{s}$ in most of the books but the correct answer is $2\mathrm{m}/\mathrm{s}$ )