Refraction Through Lenses

Class 10 Physics Chapter 4
Refraction through lenses
Important Questions

Exam preparation with oswal.ioExam preparation with oswal.io

Refraction of light through a lens is a fundamental concept in optics. Lenses are transparent optical components that use refraction to bend and focus light. There are two primary types of lenses: convex and concave, each with distinct properties in terms of how they refract light. Class 10 Refraction through lenses important questions and answers cover a range of topics related to the refraction of light through lenses and their practical applications. They can be used for study, discussion, or assessment of knowledge in the field of optics.

Introduction

The refraction of light through lenses is a fundamental and captivating phenomenon in the field of optics. Lenses are transparent optical elements that have the remarkable ability to bend and focus light, giving rise to numerous applications in science, technology, and everyday life. The refraction of light through lenses is not only a scientific principle but also a cornerstone of technological innovation that touches our lives in many ways. If you want to prepare well then below are some important questions for class 10 ICSE physics.

What are Refraction through lenses?

Refraction through a lens is a fundamental concept in optics that involves the bending of light as it passes through a transparent lens. Lenses are optical devices made of transparent material, such as glass or plastic, and they are shaped to manipulate the path of light through refraction. There are two primary types of lenses: convex and concave, each with its own distinct properties when it comes to refraction.

important questions for class 10 icse physics

Class 10 Refraction through lenses Important Questions and Answers

Q1. An object is placed at a distance of more than 40cm from a convex lens of focal length 20cm. The image formed is real, inverted and ................ .

Options

(a) diminished
(b)  same as (or equal to)
(c) magnified
(d) none of the above

Ans. (a) diminished

Explanation:
The image formed is real since (v is positive), inverted (as all real images formed by a convex lens are inverted when the object is placed beyond the focus), and located slightly beyond the point which is twice the focal length (i.e., slightly beyond 40cm) on the opposite side of the lens from the object.

Q2. The plano-convex lens has

Options

(a) Both surfaces convex
(b) One plane, One convex
(c) One convex, one concave
(d) both concave

Ans. (b) One plane, One convex
Explanation:
A plano-convex lens is a type of lens where one side is flat (plane) and the other side curved outward (convex).plano-convex lens is a versatile optical component with a range of applications in various optical systems and instruments. The choice to use this type of lens often comes down to specific system requirements and design considerations.

Q3. Why is the focal length of the lens used as magnifying glass kept short?

Explanation:
The focal length of the lens used as magnifying glass is kept small to increase its magnifying power. A magnifying glass, which is essentially a simple convex lens, is used to magnify small objects or fine details in objects. The magnifying power (or angular magnification) of a simple convex lens when used as a magnifying glass is related to its focal length.

Q4. The following diagram shows the object O and the image I formed with a lens. Copy the diagram and on it mark the positions of the lens LL’ and focus (F). Name the lens.

refraction_through_lenses_Q4

Explanation:
The complete diagram is shown in the below figure in which the position of lens has been marked by the letter LL′. and the focus as F. The lens is convex (or converging).

refraction_through_lenses_ans4

Q5. If lens is of focal length 25 cm. Calculate the power of the lens.?

Explanation: Focal length = 25 cm = 0.25 m

  • P is the power of the lens (measured in diopters, D).
  • f is the focal length of the lens (measured in meters).

For a converging lens (like a convex lens), the focal length is positive, so its power is also positive. For a diverging lens (like a concave lens), the focal length is negative, so its power is negative.
This relationship implies that a lens with a short focal length has a high power, and a lens with a long focal length has low power.

important questions for class 10 icse physicsimportant questions for class 10 icse physics

ICSE Class 10 Physics Chapter wise Important Questions

Chapter No. Chapter Name
Chapter 1 Force Work Power and Energy
Chapter 2 Simple Machines
Chapter 3 Refraction of Light
Chapter 4 Refraction Through Lenses
Chapter 5 Spectrum
Chapter 6 Vibrations of Sound
Chapter 7 Sound
Chapter 8 Electricity
Chapter 9 Electrical Power and Household Circuits
Chapter 10 Magnetic Effect of Current
Chapter 11 Specific Heat Capacity and Latent Heat
Chapter 12 Radioactivity and Nuclear Energy

Conclusion

The phenomenon of refraction through lenses is a fundamental concept in optics with a wide range of applications and implications. Convex and concave lenses, due to their unique shapes and refractive properties, play a crucial role in manipulating the path of light and creating various optical effects. For those looking for extra practice and a better grasp of the chapter's concepts, oswal.io provides a wide range of class 10 Refraction through lenses important questions and answers allowing for a more in-depth comprehension of the subject.

Frequently Asked Questions

Q1 : What is refraction through a lens?

Ans : Refraction through a lens refers to the bending of light as it passes through a transparent lens, resulting in changes in the path of light rays.

Q2 : What are the two primary types of lenses, and how do they differ in terms of refraction?

Ans : The two primary types of lenses are convex and concave lenses. Convex lenses converge light, while concave lenses diverge light.

Q3 : What is the focal point of a lens?

Ans : The focal point is the point where either real or virtual images are formed, depending on the type of lens. It is the point where parallel rays of light converge (for convex lenses) or appear to diverge from (for concave lenses).

Q4 : How is the focal length of a lens defined, and what does it signify?

Ans : The focal length (f) is the distance between the lens and the focal point. It indicates the lens's ability to focus light and is a measure of its optical power

Q5 : Can you explain the concept of total internal reflection in lenses?

Ans: Total internal reflection is a phenomenon that occurs when light cannot pass from a medium with a higher refractive index to a medium with a lower refractive index. It is relevant to certain optical applications, including fibre optics.

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