CBSE Class 10 Science Notes Chapter 10:
You can find the notes for Grade 10 Science's NCERT-based notes in Chapter 10 here. By studying for the exams in advance, these notes will help students ace their exams. The Science NCERT Notes for Class 10 in this chapter, provided by us, can help students with all of their conceptual issues and doubts.
These NCERT Notes have been prepared by experts using the most recent revision of the CBSE syllabus to assist students in Class 10 in adequately preparing for their examinations.
CBSE Class 10 Science Notes Chapter 10 Overview
Students learn about the processes of light reflection and refraction utilising the straight-line propagation of light in Class 10 Science Chapter 10 Light.
CBSE Class 10 Science Notes
Additionally, natural visual phenomena are investigated. The chapter discusses spherical mirrors' ability to reflect light, allowing for an examination of their practical applications.
CBSE Class 10 Science Notes Chapter 10 PDF
Get the Class 10 Light Reflection and Refraction notes here. Candidates who are determined to pass the Class 10 exam with a high score should review the notes in this article.
The link to the Class 10 Science Notes on the topic of Light Reflection and Refraction is provided below.
CBSE Class 10 Science Notes Chapter 10 PDF
CBSE Class 10 Science Notes Chapter 10
Light
One type of energy that gives us the ability to perceive things is light. Light originates from a source, reflects off of objects that our eyes detect, and is then processed by our brain to allow us to see.
According to Maxwell's theory, waves made up of electric and magnetic fields travel at the speed of light. As a result, Maxwell postulated that electromagnetic waves carry light, indicating that light is a type of radiation.
Nature of Light
Light behaves as a:
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ray, e.g. reflection
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wave, e.g. interference and diffraction
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particle, e.g. photoelectric effect
In quantum physics, the idea of wave-particle duality states that light can behave like a particle or like a wave, depending on the situation.
If light were thought of as a wave, phenomena like diffraction, polarisation, and interference could be explained. One way to explain a phenomenon such as the photoelectric effect is to assume that light is made up of particles known as photons.
Laws of Reflection
Light Incident on the Surface Separating Two Media
Light moves in one of two ways when it moves between media:
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gets absorbed (absorption)
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bounces back (reflection)
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passes through or bends (refraction)
A plane mirror reflects the majority of incident light, with the remaining portion being absorbed by the medium.
Characteristics of Light
The formula for the speed of light is c=λμ, where λ stands for wavelength and μ for frequency.
The constant speed of light is 2.998×108m/s, or around 3.0×108m/s.
Reflection of Light by Other Media
Regular light reflection results from a medium with a well-polished surface free of flaws. Take a plane mirror, for instance. Even yet, the surface still absorbs some light.
Laws of Reflection
The incident ray, reflected ray and the normal all lie in the same plane. Angle of incidence = Angle of reflection
[
∠
i
=
∠
r
]
Fermat’s Principle
The least-time principle states that light always chooses the fastest route between any two points, even if it's not the shortest one.
Fermat's principle of least time can be used to support the law of reflection [−i=−r] and the rectilinear propagation of light.
Applications of Fermat’s Principle
Fermat's Principle allows us to make several observations that will be helpful as we go more into the field of geometric optics:
Light beams in a homogenous medium are rectilinear. That is, light moves in a straight line through any medium where the index of refraction is constant.
An angle of incidence and reflection on a surface are equal. The Law of Reflection is this.
Example of Fermat’s Principle
One illustration of this phenomenon is Mirage. On occasion, we may perceive water on the route, but upon arrival, we find that it is dry. The light from the sky that is reflected on the road is what we see.
Since it is colder higher up, the air is much hotter just over the road. Because hot air is thinner and expands faster than cool air, the speed of light decreases less.
Image Formation by a Plane Mirror
A planar mirror always creates an erect, imaginary picture.
Both the image and the object are equally spaced from the mirror.
Characteristics of Images
Pictures can be virtual or actual, upright or upside down, and enlarged or smaller. The actual convergence of light beams creates a real image. An apparent convergence of light beams that are diverging is called a virtual picture.
An image is said to be either inverted or upright depending on whether it is generated upside down. Magnified refers to a picture generated that is larger than the object. It is diminished if the produced picture is smaller than the object.
Rules of Ray Diagram for Representation of Images Formed
When a ray strikes the concave spherical mirror while traveling through the center of curvature, it retraces its route.
The focus or focal point is traversed by rays that are parallel to the primary axis.
Image Formation by Spherical Mirrors
The ray diagrams for the special two rays can be used to find the image created for objects at different places. The concave mirror is shown in the following table.
Properties of Concave mirror
• Reflecting surface is curved inwards.
• Converging mirror
Properties of Convex mirror
• Reflecting surface is curved outwards.
• Diverging mirror
Ray diagrams of images formed by convex mirror
(i) When object is placed at infinity
Image Position − At ‘F’
Nature of image – Virtual, erect
Size – Point sized
(ii) When object is placed between pole and infinity
Image Position – Between ‘P’ and ‘F’
Nature of image– Virtual, erect
Size – Diminished
where "u" stands for object distance, "v" for image distance, and "f" for the spherical mirror's focal length—which is determined by how similar the triangles are—are all expressed.
The ratio of the image height to the object height is the magnification that a spherical mirror produces. Typically, it is shown as'm'.
Sign Convention for Ray Diagram
The coordinate system's positive x and y axes represent distances, while the negative x and y axes represent distances.
Remember that the pole (P) is the origin. In most cases, an object's height is measured as positive when it is above the principal axis, while an image's height is measured as negative when it is below the principal axis.
Refraction Through a Glass Slab and Refractive Index
Refraction
Not always is the shortest path the fastest. Since light travels at the fastest possible speed, it bends when it passes through different materials. Refraction is the term used to describe the phenomena of light bending in a different medium.
Laws of Refraction
At the point of incidence, the incident ray, refracted ray, and normal to the interface of two transparent media all lie in the same plane.
For a given pair of media and a given colour of light, the ratio of the sines of the angles of incidence and refraction is constant. Snell's law of refraction is another name for this law.
Refractive Index
The refractive index measures how much light bends when it passes through different materials. The ratio of the speeds in the two media determines this. The amount of bending increases with the ratio.
In addition, it is the constant ratio between the sines of the angles of incidence and refraction for each given pair of media. It is indicated by:
n = sin∠i/sin∠r = speed of light in medium 1/speed of light in medium2.
The relative refractive index is the product of the speed of monochromatic light in the substance of interest and the speed of light in a vacuum. In mathematical notation, it is expressed as:
n = c/v
where v is the light's velocity within that specific medium, c is the light's velocity in a vacuum, and n is the medium's refractive index.
Image Formation by Spherical Lenses
A convex lens's ability to generate images is displayed in the table below.
Sign Convention for Reflection by Spherical Mirror
The item is positioned with the mirror on the left.
The mirror's pole is the starting point for all measurements of lengths parallel to the major axis.
All distances measured along the X-axis and in the direction of the incident ray are considered positive, whereas all distances measured along the X-axis and in the opposite direction of the incident ray are considered negative.
Measurements of distance above and perpendicular to the primary axis are interpreted as positive.
Measurements taken below and perpendicular to the primary axis are interpreted as negative.
Object distance = ‘u’ is always negative.
Focal length of concave mirror = Negative
Focal length of convex mirror = Positive
Power of a Lens
A lens's power is equal to 1/f (in metres), which is the reciprocal of its focal length. The dioptre (D) is the SI unit of power for a lens.
