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can anyone provide me notes of reflection and refraction of light [class 10][cbse]
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Answered by gilllakhwindrr60
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Explanation:

CBSE Class 10 Science Notes Chapter 10 Light Reflection and Refraction

REFLECTION

Reflection of Light: The phenomenon of bouncing back of light into the same medium by the smooth surface is called reflection.

Incident light: Light which falls on the surface is called incident light.

Reflected light: Light which goes back after reflection is called reflected light.

The angle of incidence: The angle between the incident ray and the normal.

An angle of reflection: The angle between the reflected ray and the normal.

Mirror: The surface which can reflect the light is a mirror.

Plane Mirror: If the reflecting surface is a plane then the mirror is plane.

Spherical Mirror: If the reflecting surface is part of the hollow sphere then the mirror is a spherical mirror.

The spherical mirror is of two types:

Convex mirror: In this mirror reflecting surface is convex. It diverges the light so it is also called a diverging mirror.

Concave mirror: In this mirror reflecting surface is concave. It converges the light so it is also called converging mirror.

Parameters of Mirror:

Center of Curvature: The centre of hollow sphere of which mirror is a part.

The radius of curvature: The radius of hollow sphere of which mirror is a part.

Pole: The centre of mirror (middle point) is pole.

Principal axis: The line joining the pole and center of curvature is called principal axis.

Aperture: Size of mirror is called aperture of mirror.

Principal Focus: The point on the principal axis, where all the incident rays parallel to principal axis converge or diverge after reflection through mirror.

Focal Length: The distance between pole and focus point is focal length.

Special Rays for Formation of Image:

A ray of light which is parallel to the principal axis of a spherical mirror, after reflection converges or diverges from focus.

A ray of light passing through or appearing from the center of curvature of spherical mirror is reflected back along the same path.

A ray of light passing through or appearing from the focus of spherical mirror becomes parallel to the principal axis.

A ray of light which is incident at the pole of a spherical mirror is reflected back making same angle with principal axis.

Use of Concave Mirror: It is used as a makeup mirror, the reflector in torches, in headlights of cars and searchlights, doctor’s head-mirrors, solar furnace, etc.

Sign Conventions of Spherical Mirror

All the distances are measured from the pole of the mirror as the origin.

Distances measured in the direction of incident rays are taken as positive.

Distances measured opposite to the direction of incident rays are taken as negative.

Distances measured upward and perpendicular to the principal axis are taken as positive.

Distances measured downward and perpendicular to the principal axis are taken as negative.

…where f, v and u are focal length, image distance, object distance

Linear Magnification: This is the ratio of the height of the image to the height of the object.

…where m = magnification, h = height of image, h’ = height of object

Use of Convex Mirror: Convex mirror used as rear view mirror in vehicles, as shop security mirrors, etc.

REFRACTION

Refraction of Light: The bending of light at the interface of two different mediums is called Refraction of light.

If the velocity of light in medium is more, then medium is called optical rarer.

Example, air or vacuum is more optical rarer.

If the velocity of light in medium is less, then medium is called optical denser.

Example, glass is more denser than air.

Refractive Index: It represents the amount or extent of bending of light when it passes from one medium to another.

There are two types of refractive index

Relative refractive index and

Absolute refractive index.

Refractive index of medium with respect to other medium is called Relative Refractive Index.

Refractive index of medium 1 with respect to medium 2 =

Refractive index of medium with respect to air or vacuum is called Absolute Refractive Index.

Absolute refractive index of medium (m) =

Incident ray: It is incoming ray on the refracting surface.

Refracted ray: It is an outgoing ray from the refracting surface.

An angle of incidence (i): It is the angle between incident rays and perpendicular line (normal) at the point of incidence.

An angle of refraction (r): It is the angle between refracted rays and perpendicular line (normal) at the point of incidence.

Law of Refraction: According to this law

“The incident ray, refracted ray and normal at the point of incidence all lie in the same plane.”

“The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.”

= constant (µ)

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Answered by venkatmahesh06
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Answer:

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Light: Definition

Light is a form of energy that enables us to see things. Light starts from a source and bounces off objects which are perceived by our eyes and our brain processes this signal, which eventually enables us to see.

Nature of Light

Light behaves as a:

ray, e.g. reflection

wave, e.g. interference and diffraction

particle, e.g. photoelectric effect

Laws of Reflection

Light incident on another medium

When light travels from one medium to another medium it either:

gets absorbed (absorption)

bounces back (reflection)

passes through or bends (refraction)

When light is incident on a plane mirror, most of it gets reflected, and some of it gets absorbed in the medium.

Characteristics of light

Speed of light c=λ×μ, where λ is its wavelength and μ  is its frequency.

Speed of light is a constant which is 2.998×108m/s or approximately 3.0×108m/s.

Reflection of light by other media

A medium that is polished well without any irregularities on its surface will cause regular reflection of light. For example, a plane mirror. But even then some light gets absorbed by the surface.

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]

Propagation of light

Rectilinear propagation of light: Light travels in a straight line between any two points.

Fermat’s Theorem

The principle of least time: Light always takes the quickest path between any two points (which may not be the shortest path).

Rectilinear propagation of light and the law of reflection  [∠i=∠r] can be validated by Fermat’s principle of least time.

Plane mirror

Any flat and polished surface that has almost no irregularities on its surface that reflect light is called as a plane mirror.

Characteristics of images

Images can be real or virtual, erect or inverted, magnified or diminished. A real image is formed by the actual convergence of light rays. A virtual image is the apparent convergence of diverging light rays.

If an image formed is upside down then it is called inverted or else it is an erect image. If the image formed is bigger than the object, then it is called magnified. If the image formed is smaller than the object, then it is diminished.

Image formation by a plane mirror

The image formed by a plane mirror is always virtual and erect.

Object and image are equidistant from the mirror.

Principle of Reversibility of light

If the direction of a ray of light is reversed due to reflection off a surface, then it will retrace its path.

Spherical Mirrors

Spherical mirror

Consider a hollow sphere with a very smooth and polished inside surface and an outer surface with a coating of mercury so that no light can come out. Then if we cut a thin slice out of the shell, we get a curved mirror, which is called a spherical mirror.

Relationship between focus and radius of curvature

Focal length is half the distance between pole and radius of curvature.

F = R/2

Curved Mirror

A mirror (or any polished, reflective surface) with a curvature is known as a curved mirror.

Important terms related to spherical mirror

Pole (P): The midpoint of a spherical mirror.

Centre of curvature (C): The centre of the sphere that the spherical mirror was a part of.

The radius of curvature (r): The distance between the centre of curvature and the spherical mirror. This radius will intersect the mirror at the pole (P).

Principal Axis: The line passing through the pole and the centre of curvature is the main or principal axis.

Concave Mirror: A spherical mirror with the reflecting surface that bulges inwards.

Convex Mirror: A spherical mirror with the reflecting surface that bulges outwards.

Focus (F): Take a concave mirror. All rays parallel to the principal axis converge at a point between the pole and the centre of curvature. This point is called as the focal point or focus.

Focal length: Distance between pole and focus.

Rules of ray diagram for representation of images formed

 A ray passing through the centre of curvature hits the concave spherical mirror and retraces its path.

Rays parallel to the principal axis passes through the focal point or focus.

Image formation by spherical mirrors

For objects at various positions, the image formed can be found using the ray diagrams for the special two rays. The following table is for a concave mirror.

 

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