Light Reflection and Refraction Full Chapter Class 10
(Animation) | CBSE Science Ch10 | NCERT
Grade booster
Music: Light Reflection and Refraction
In this chapter, we will study the reflection and refraction of light. Light is a form of energy
that travels in a straight line. When a light ray strikes a smooth, polished surface like a mirror,
it bounces back. This is called reflection of light. Mirrors are opaque objects with shiny
reflective surfaces that allow us to see our images. Refraction of light occurs when a light
ray passes from one medium to another, causing a change in its direction. This can be
observed when a straw appears to be bent in a glass. Lenses, such as eyeglasses, are
transparent objects that also demonstrate the refraction of light.
Reflection of Light with Mirrors
When a light ray strikes a plain mirror, it is reflected back according to the laws of reflection.
The angle of reflection is equal to the angle of incidence. Plane mirrors create virtual images
that appear to be located behind the mirror at the same distance as the object in front of the
mirror. These virtual images cannot be projected onto a screen and are formed by the
apparent intersection of reflected light rays when extended backward.
● Size and Magnification: The size of the image in a plain mirror is the same as the
size of the object. There is no magnification, meaning that objects in a plain mirror
appear to be the same size as they are in reality.
● Laterally Reversed: The images formed by plain mirrors are laterally reversed, also
known as left-right reversed. This means that if you raise your right hand in front
of a plain mirror, your image will appear to raise its left hand.
Reflection of Light by Spherical Mirrors
Spherical mirrors are curved mirrors that form part of a sphere. There are two types of
spherical mirrors: convex mirrors, which have an outward curved reflective surface, and
, concave mirrors, which have an inward curved reflective surface. To understand reflection by
spherical mirrors, we need to know certain terms:
● Pole: The center point of the reflecting surface of a spherical mirror is called the
pole.
● Center of Curvature: The center of curvature is the center of the imaginary sphere
from which the spherical mirror is derived. It lies behind the mirror for convex
mirrors and in front of the reflecting surface for concave mirrors.
● Radius of Curvature: The radius of curvature is the radius of the imaginary sphere
of which the mirror is a part.
● Principal Axis: The line joining the pole and the center of curvature is called the
principal axis. The principal axis is normal to the mirror at its pole, meaning the
angle between the plane of the mirror and the principal axis is 90 degrees.
● Principal Focus: If a number of light rays parallel to the principal axis are falling on
a concave mirror, they all meet or intersect at a point on the principal axis. This
point is called the principal focus of the concave mirror. In the case of a convex
mirror, the reflected rays appear to come from a point on the principal axis. This
point is called the principal focus of the convex mirror.
● Focal Length: The distance between the pole and the principal focus of a spherical
mirror is called the focal length.
● Aperture: The diameter of the reflecting surface of the spherical mirror is called its
aperture.
In this chapter, we will discuss spherical mirrors with apertures smaller than their radius of
curvature. The relationship between the radius of curvature (r) and the focal length (f) of a
spherical mirror is given by the equation r = 2f.
Image Formation by Spherical Mirrors
Ray diagrams are used to represent images formed by spherical mirrors. There are certain
rules for making these ray diagrams:
● Parallel Ray Rule: For a concave mirror, if a light ray passes parallel to the principal
axis, after reflecting it passes through the focal point (F). For a convex mirror, if a
light ray passes parallel to the principal axis, after reflecting it appears to come
from the focal point (F) behind the mirror.
● Focal Ray Rule: For a concave mirror, if a light ray passes through the principal
focus (F) after reflection, it emerges parallel to the principal axis. For a convex
mirror, if a light ray is directed towards the principal focus (F) after reflection, it
emerges parallel to the principal axis.
● Center of Curvature Ray Rule: For a concave mirror, if a light ray goes from the
object to the center of curvature (C) after reflection, it retraces its path back to the
(Animation) | CBSE Science Ch10 | NCERT
Grade booster
Music: Light Reflection and Refraction
In this chapter, we will study the reflection and refraction of light. Light is a form of energy
that travels in a straight line. When a light ray strikes a smooth, polished surface like a mirror,
it bounces back. This is called reflection of light. Mirrors are opaque objects with shiny
reflective surfaces that allow us to see our images. Refraction of light occurs when a light
ray passes from one medium to another, causing a change in its direction. This can be
observed when a straw appears to be bent in a glass. Lenses, such as eyeglasses, are
transparent objects that also demonstrate the refraction of light.
Reflection of Light with Mirrors
When a light ray strikes a plain mirror, it is reflected back according to the laws of reflection.
The angle of reflection is equal to the angle of incidence. Plane mirrors create virtual images
that appear to be located behind the mirror at the same distance as the object in front of the
mirror. These virtual images cannot be projected onto a screen and are formed by the
apparent intersection of reflected light rays when extended backward.
● Size and Magnification: The size of the image in a plain mirror is the same as the
size of the object. There is no magnification, meaning that objects in a plain mirror
appear to be the same size as they are in reality.
● Laterally Reversed: The images formed by plain mirrors are laterally reversed, also
known as left-right reversed. This means that if you raise your right hand in front
of a plain mirror, your image will appear to raise its left hand.
Reflection of Light by Spherical Mirrors
Spherical mirrors are curved mirrors that form part of a sphere. There are two types of
spherical mirrors: convex mirrors, which have an outward curved reflective surface, and
, concave mirrors, which have an inward curved reflective surface. To understand reflection by
spherical mirrors, we need to know certain terms:
● Pole: The center point of the reflecting surface of a spherical mirror is called the
pole.
● Center of Curvature: The center of curvature is the center of the imaginary sphere
from which the spherical mirror is derived. It lies behind the mirror for convex
mirrors and in front of the reflecting surface for concave mirrors.
● Radius of Curvature: The radius of curvature is the radius of the imaginary sphere
of which the mirror is a part.
● Principal Axis: The line joining the pole and the center of curvature is called the
principal axis. The principal axis is normal to the mirror at its pole, meaning the
angle between the plane of the mirror and the principal axis is 90 degrees.
● Principal Focus: If a number of light rays parallel to the principal axis are falling on
a concave mirror, they all meet or intersect at a point on the principal axis. This
point is called the principal focus of the concave mirror. In the case of a convex
mirror, the reflected rays appear to come from a point on the principal axis. This
point is called the principal focus of the convex mirror.
● Focal Length: The distance between the pole and the principal focus of a spherical
mirror is called the focal length.
● Aperture: The diameter of the reflecting surface of the spherical mirror is called its
aperture.
In this chapter, we will discuss spherical mirrors with apertures smaller than their radius of
curvature. The relationship between the radius of curvature (r) and the focal length (f) of a
spherical mirror is given by the equation r = 2f.
Image Formation by Spherical Mirrors
Ray diagrams are used to represent images formed by spherical mirrors. There are certain
rules for making these ray diagrams:
● Parallel Ray Rule: For a concave mirror, if a light ray passes parallel to the principal
axis, after reflecting it passes through the focal point (F). For a convex mirror, if a
light ray passes parallel to the principal axis, after reflecting it appears to come
from the focal point (F) behind the mirror.
● Focal Ray Rule: For a concave mirror, if a light ray passes through the principal
focus (F) after reflection, it emerges parallel to the principal axis. For a convex
mirror, if a light ray is directed towards the principal focus (F) after reflection, it
emerges parallel to the principal axis.
● Center of Curvature Ray Rule: For a concave mirror, if a light ray goes from the
object to the center of curvature (C) after reflection, it retraces its path back to the
