Cbse (Cce) Sample Questions | Class 10, LIGHT - REFLECTION AND REFRACTION | Solutions of Ncert Science - Physics | Notes, Study Materials, Important Questions

 


10th NCERT (CBSE) Guide - Science Physics

Class X, LIGHT - REFLECTION AND REFRACTION

NCERT Physics (Science) – CBSE Class 10 Notes, Study Materials

LESSON 3 of 3

 Light – Reflection and Refraction:   

Lesson 1 of 3 [Read
Lesson 2 of 3 [Read]
Image Formation by a Convex Lens
                                                            (Table followed by figures)

Position of the object
Position of the image
Size of image
Nature of image
1
At infinity
At focus F2
Highly diminished, point sized
Real, inverted
2
Beyond 2F1
Between F2 and 2F2
Diminished
Real, inverted
3
At 2F1
At 2F2
Same size
Real, inverted
4
Between F1 and 2F1
Beyond 2F2
Enlarged
Real, inverted
5
At focus F1
At infinity
Infinitely large or highly enlarged
Real, inverted
6
Between focus F1 and optic center O
On the same side of the lens as the object
Enlarged
Virtual, erect


 Image Formation by a Concave Lens
                                                        (Table followed by figures)

Position of object
Position of image
Size of image
Nature of image
1
At the infinity
At focus F1
Highly diminished, point-sized
Virtual, erect.
2
Between infinity and optical center of the lens
Between focus F1 and optical center O.
Diminished
Virtual, erect.
Sign Convention (Spherical Lenses)
The following table summarizes the New Cartesian Sign Convention for spherical lenses:
Lens
Distance of object (u)
Distance of image (v)
Focal length (f)
Height of object
Height of image
Real image
Virtual image
Real image
Virtual image
Convex
– ve
+ ve
– ve
+ ve
+ ve
– ve
+ ve
Concave
– ve

– ve
– ve
+ ve

+ ve

CCE Type CBSE Sample Questions
Q.1: What are the differences between a spherical mirror and a lens?
Ans: The differences between a spherical mirror and a lens are listed below:
Spherical Mirror
  • In a spherical mirror image is formed by reflection of light.
  • t has a single focus. 
  • The center of the spherical mirror is known by the term Pole.
Spherical Lens
  • Here image is formed by refraction of light.
  • It has two foci. 
  • The center of the spherical mirror is known by the term Optical Center.
Q.2: For which colour the refractive index of material is the maximum?
Ans: For violet colour the refractive index of material is the maximum.
Q.3: Will there be any change in focal length of a concave mirror or concave lens when it is dipped in water?
Ans: No, because the focal length is independent of the refractive index of the material of mirror (or lens) and surrounding medium.
Q.4: When light undergoes refraction, what happens to its wavelength, frequency?
Ans: Wavelength of light decreases on entering a denser medium and increases on entering a rarer medium. Frequency of light will remain same.
Q.5: What is the focal length of a plane mirror?
Ans: It is infinity, as the plane mirror is considered to be part of a spherical mirror whose radius is infinite.
Q.6: What is the magnification produced by a plane mirror?
Ans: The magnification produced by a plane mirror is +1.
Q.7: What is the emergent angle of light after refraction in a glass slab?
Ans: The direction of the light after refraction in a glass slab will be parallel to the incident ray of light. Hence, the emergent angle will be equal to the angle of incidence.
Q.8: Magnification (m) of a plane mirror is +1. What does 1 and +ve sign signify?
Ans: m = +1 signify that image is erect, virtual and of equal size.
Q.9: Why is convex lens used in magnifying glass? Or, What is magnifying glass?
Ans: A magnifying glass is used to read small prints or see very small things. A convex lens produces virtual, erect and magnified image of an object when it is placed close to the lens. Because of this property of the convex lens it is used in magnifying glass to view magnified image of the objects.
Q.10: Why a concave lens is called diverging lens?
Ans:
Fig: Diverging Lens
When a beam of light parallel to the principal axis falls on a concave lens then they appear to be diverging from a single point, also known as principal focus (F) of the lens. Therefore, a concave lens is also known as Diverging Lens.      

Class 10, Light – Reflection and Refraction: earlier posted lessons 

Lesson 1 of 3 [Read
Lesson 2 of 3 [Read]

Further Study on Chapter 10, Light - Reflection and Refraction

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