Reflection of Light
Reflection of Light
The return of light into the same medium after striking a surface is called reflection.
We see the objects around us due to reflection.
A plane mirror reflects almost all the light falling on it.
Kinds of Reflection
Regular Reflection
When a beam of light falls on a smooth and polished surface (a plane mirror), regular reflection
occurs.
The incident rays and reflected rays are parallel beams.
Irregular Reflection
When a beam of light falls on a rough surface (a wall or a road), irregular reflection occurs.
The incident rays are parallel beams, but the light reflected from different surfaces will reflect at
different angles obeying the laws of reflection.
Terms Related to Reflection
Incident ray: The light ray striking a reflecting surface is called the incident ray.
Point of incidence: The point at which the incident ray strikes the reflecting surface is called the point
of incidence.
, Reflected ray: The light ray obtained after reflection from the surface in the same medium as the
incident ray is called the reflected ray.
Normal: The perpendicular drawn to the surface at the point of incidence is the normal.
Angle of incidence: The angle made by the incident ray with the normal at the point of incidence is
called the angle of incidence.
Plane of incidence: The plane containing the incident ray and the normal is called the plane of
incidence.
Angle of reflection: The angle made by the reflected ray with the normal at the point of incidence is
called the angle of incidence.
Plane of reflection: The plane containing the reflected ray and the normal is called the plane of
incidence.
Laws of Reflection
Reflection at a surface obeys two laws of reflection:
First law of reflection: The incident ray, the normal to the surface at the point of incidence and the
reflected ray, all lie in the same plane.
Second law of reflection: The angle of incidence is equal to the angle of reflection.
Formation of Image by Reflection
There are two types of images—real and virtual images.
1. Real image: It is the image which can be obtained on a screen. It is the image formed when light
rays actually intersect after reflection. It is an inverted image.
2. Virtual image: It cannot be obtained on a screen. It is the image formed when light rays do not
actually intersect after reflection but appear to diverge from the image. The light rays intersect
geometrically when they are produced backwards. It is an erect image.
Image of a Point Object Formed by a Plane Mirror
OA and OB are the two rays from object O incident on a plane mirror MM′. They get reflected from the
mirror by obeying the laws of reflection. AC and BD are the reflected rays.
The image I is formed behind the mirror and is located by producing AC and BD backwards. This
image is a virtual image because the reflected rays do not intersect actually.
Reflection of Light
The return of light into the same medium after striking a surface is called reflection.
We see the objects around us due to reflection.
A plane mirror reflects almost all the light falling on it.
Kinds of Reflection
Regular Reflection
When a beam of light falls on a smooth and polished surface (a plane mirror), regular reflection
occurs.
The incident rays and reflected rays are parallel beams.
Irregular Reflection
When a beam of light falls on a rough surface (a wall or a road), irregular reflection occurs.
The incident rays are parallel beams, but the light reflected from different surfaces will reflect at
different angles obeying the laws of reflection.
Terms Related to Reflection
Incident ray: The light ray striking a reflecting surface is called the incident ray.
Point of incidence: The point at which the incident ray strikes the reflecting surface is called the point
of incidence.
, Reflected ray: The light ray obtained after reflection from the surface in the same medium as the
incident ray is called the reflected ray.
Normal: The perpendicular drawn to the surface at the point of incidence is the normal.
Angle of incidence: The angle made by the incident ray with the normal at the point of incidence is
called the angle of incidence.
Plane of incidence: The plane containing the incident ray and the normal is called the plane of
incidence.
Angle of reflection: The angle made by the reflected ray with the normal at the point of incidence is
called the angle of incidence.
Plane of reflection: The plane containing the reflected ray and the normal is called the plane of
incidence.
Laws of Reflection
Reflection at a surface obeys two laws of reflection:
First law of reflection: The incident ray, the normal to the surface at the point of incidence and the
reflected ray, all lie in the same plane.
Second law of reflection: The angle of incidence is equal to the angle of reflection.
Formation of Image by Reflection
There are two types of images—real and virtual images.
1. Real image: It is the image which can be obtained on a screen. It is the image formed when light
rays actually intersect after reflection. It is an inverted image.
2. Virtual image: It cannot be obtained on a screen. It is the image formed when light rays do not
actually intersect after reflection but appear to diverge from the image. The light rays intersect
geometrically when they are produced backwards. It is an erect image.
Image of a Point Object Formed by a Plane Mirror
OA and OB are the two rays from object O incident on a plane mirror MM′. They get reflected from the
mirror by obeying the laws of reflection. AC and BD are the reflected rays.
The image I is formed behind the mirror and is located by producing AC and BD backwards. This
image is a virtual image because the reflected rays do not intersect actually.
