# NCERT Solutions for Class 10 Science Chapter 10

NCERT Solutions for Class 10 Science Chapter 10 Light – Reflection and Refraction all intext questions given on Page 168 or Page 171 or Page 176 or Page 184 or Exercises in English and Hindi Medium free. Download all answers in PDF file format or download Offline apps 2021-2022 to use all the contents offline without internet. UP Board students are also using NCERT Textbook for their final exams. So, 10th Science chapter 10 question answers are useful for UP Board students also. Download here the UP Board Solutions for Class 10 Science Chapter 10 in Hindi Medium to view online or download free in PDF format.

Important questions and CBSE previous years board questions related to chapter 10 are given with answers. All NCERT Solutions as well as Offline Apps are based on latest NCERT Books 2021-22 following the latest CBSE Syllabus 2021-2022.

## NCERT Solutions for Class 10 Science Chapter 10

• ### 10th Science Chapter 10 Answers in PDF Form

 Class: 10 Science (English and Hindi Medium) Chapter 10: Light – Reflection and Refraction

### 10th Science Chapter 10 Answers in English & Hindi Medium

NCERT Solutions for Class 10 Science Chapter 10 Light – Reflection and Refraction all the question answers of intext questions as well as chapter end exercises are given below updated for 2021-22. NCERT solutions 2021-22 for class 10 other subjects are also in PDF as well as online to use.

### Class 10 Science Chapter 10 Extra Question Answer

##### List four properties of the image formed by a plane mirror.

Properties of images formed by a plane mirrors:

1. The image formed by a plane mirror is virtual and erect.
2. It is of the same size as the object.
3. The image is formed as far behind the mirror as the object is in front of it i.e., u = v.
4. It is laterally inverted i.e., image is inverted sideways with respect to the object.
##### List the four properties of the image formed by a convex mirror.

Properties of the image formed by a convex mirror:

• (i) This image is always virtual and erect.
• (ii) The image is highly diminished or point sized.
• (iii) It is always formed between F and P.
• (iv) As the object is moved towards the pole of convex mirror, image also moves towards its pole and gradually increases size till its size becomes almost equal to that of the object.
##### State the laws of refraction of light.

Laws of refraction of light: The refraction of light obeys the following two laws:
First law: The incident ray, the refracted ray and normal to the surface of separation at the point of incidence, all lie in the same plane.
Second law: The ratio of the sine of the angle of incidence and the sine of the angle of refraction is constant for a given pair of media. Mathematically,
[sin i] / [sin r] = n (a constant).
The ratio n2 is called refractive index of the second medium with respect to the first medium. The second law of refraction is also called Snell’s law of refraction.

##### What is meant by refraction of light?

Refraction of light: The phenomenon of bending of light from its straight line path as it passes obliquely from one transparent medium to another is called refraction of light.
The path of the ray of light in the first medium is called incident ray.
The path of the ray of light in the second medium is called refracted ray.
The angle between the incident ray and the normal at the surface of separation is called angle of incidence (i).
The angle between the refracted ray and the normal at the surface of separation is called angle of refraction (r).

#### Questions for Practice

Question 1:
Give three points of difference between real and virtual images.
Real Image:
(i) Here the rays actually meet at the image point.
(ii) It can be taken on a screen.
(iii) It is always inverted
Virtual Image:
(i) Here the rays appear to diverge from the image point.
(ii) It cannot be taken on a screen.
(iii) It is always erect.

Question 2:
Distinguish between a concave and convex lens.
Convex lens
(a) It is thicker at the centre than at the edges.
(b) It converges a parallel beam of light on refraction through it.
(c) It has a real focus.
Concave lens:
(a) It is thinner at the centre than at the edges.
(b) It diverges a parallel beam of light on refraction through it.
(c) It has a virtual focus.

##### Questions from Board Papers

Question 1:
Define the principal focus of a concave mirror. Calculate the focal length of the mirror of radius of curvature of 20 cm.
The principal focus of concave mirror is a point on its principal axis at which a beam of light parallel to the principal axis actually converges after reflection from the mirror.
Focal length = R/2 = 20/2 = 10 cm.

Question 2:
State the type of mirror preferred as
(i) rear view mirror in vehicles,
(ii) shaving mirror. Justify your answer giving two reason in each case.
(i) A convex mirror is preferred as a rear-view mirror because
(a) It always forms an erect, virtual and diminished image of an object placed anywhere in front of it.
(b) It has wider field of view.
(ii) A concave mirror is preferred as a shaving mirror because when it is held closer to the face, it form:
(a) an enlarged image of the face
(b) an erect image of the face

### Important Questions on 10th Science Chapter 10

##### Define the principal focus of a concave mirror.

Light rays that are parallel to the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror. This point is known as the principal focus of the concave mirror.

##### The radius of curvature of a spherical mirror is 20 cm. What is its focal length?

Radius of curvature, R = 20 cm Radius of curvature of a spherical mirror = 2 × Focal length (f) R = 2f f = r/2 = 20/2 = 10 cm Hence, the focal length of the given spherical mirror is 10 cm.

##### Name the mirror that can give an erect and enlarged image of an object.

When an object is placed between the pole and the principal focus of a concave mirror, the image formed is virtual, erect, and enlarged.

##### Why do we prefer a convex mirror as a rear-view mirror in vehicles?

Convex mirrors give a virtual, erect, and diminished image of the objects placed in front of them. They are preferred as a rear-view mirror in vehicles because they give a wider field of view, which allows the driver to see most of the traffic behind him.

##### A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or away from the normal? Why?

The light ray bends towards the normal. When a ray of light travels from an optically rarer medium to an optically denser medium, it gets bent towards the normal. Since water is optically denser than air, a ray of light travelling from air into the water will bend towards the normal.

##### The refractive index of diamond is 2.42. What is the meaning of this statement?

Refractive index of a medium nm is related to the speed of light in that medium v by the relation: n = c/v Where, c is the speed of light in vacuum/air The refractive index of diamond is 2.42. This suggests that the speed of light in diamond will reduce by a factor 2.42 compared to its speed in air.

##### Define 1 dioptre of power of a lens.

Power of lens is defined as the reciprocal of its focal length. If P is the power of a lens of focal length F in metres, then P = 1/f The S.I. unit of power of a lens is Dioptre. It is denoted by D. 1 dioptre is defined as the power of a lens of focal length 1 metre. 1 D = 1 per meter

##### Which concepts will students study in chapter 10 of class 10th Science?

Concepts that students will study in chapter 10 (Light-Reflection and Refraction) of class 10th Science are:

• 1. Reflection of light
• 2. Spherical mirrors
• 3. Image Formation by Spherical Mirrors
• 4. Representation of Images Formed by Spherical Mirrors Using Ray Diagrams
• 5. Image formation by Concave Mirror
• 6. Uses of concave mirrors
• 7. Image formation by a Convex Mirror
• 8. Uses of convex mirrors
• 9. Sign Convention for Reflection by Spherical Mirrors
• 10. Mirror Formula and Magnification
• 11. Refraction of light
• 12. Refraction through a Rectangular Glass Slab
• 13. The Refractive Index
• 14. Refraction by Spherical Lenses
• 15. Image Formation by Lenses
• 16. Image Formation in Lenses Using Ray Diagrams
• 17. Sign Convention for Spherical Lenses
• 18. Lens Formula and Magnification
• 19. Power of a Lens
##### Is there any book other than NCERT for chapter 10 of class 10th Science that students can refer to at the time of exams?

Yes, there is a book other than NCERT for chapter 10 of class 10th Science that students can refer to at the exam time. The name of one of these books is NCERT Exemplar and other is Lakhmir Singh – Manjit Kaur. These books are one of the best books after NCERT. The language of these books is students friendly. Students can easily prepare chapter 10 of class 10th Science from these book. Also, students can practice different questions of chapter 10 from sample papers released by CBSE and from previous year’s board papers.

##### How many good examples are there in chapter 10 of class 10th Science?

Yes, there are four examples in chapter 10 of class 10th Science. All examples are important for the exams. Students should practice all four examples of this chapter. These examples are nice and easy.

##### Are there any activities in chapter 10 of grade 10th Science?

There are 13 activities in chapter 10 of grade 10th Science. All the activities are nice, interesting, and logical. These activities help students to understand the chapter easily and practically. Students enjoy doing these activities in school.

##### Is chapter 10 of grade 10th Science important from the exam point of view?

Yes, chapter 10 of grade 10th Science is important from the exam point of view. Every year questions come from chapter 10 in the exams. There are 31 questions and 4 examples in chapter 10. All the questions of this chapter are significant and can come in the exams. In this chapter, students face difficulty in making ray diagrams.                           