PRASHANT KIRAD Centre of Curvature (C): The center of the sphere of which
Light the mirror's reflecting surface forms a part.
- Rectilinear propagation of light - light travels in a straight line. Radius of Curvature (R): The radius of the sphere of which
8
- Speed of Light = c = 3 x 10 m/s the mirror's reflecting surface forms a part. R=2f
Reflection: The bouncing back of light from any shiny surface Principal Axis: The straight line passing through the pole and
e.g. mirror or water. the center of curvature of the mirror.
The Laws of reflection Principal Focus (F): The point where parallel rays of light
states that: either converge or appear to diverge after reflecting from the
1. The Incident ray, the mirror.
Reflected ray and Focal Length (f): The distance between the pole and the
Normal all lie in the principal focus.
same plane.
Aperture: The diameter of the reflecting surface of the
2. Angle of incidence
spherical mirror.
(∠i) = The angle of
reflection (∠r). Ray Diagrams
(i) A ray parallel to principal
Plane mirror: A smooth and polished surface that reflects axis will pass through focus
light uniformly. after reflection.
The image formed by a plane mirror is :
always virtual and erect.
(iii) A ray passing through
size of the image is equal to that of the object.
center of curvature will
image formed is as far behind the mirror as the object is
follow the same path back
in front of it.
after reflection.
image is laterally inverted.
Spherical mirror: a mirror whose reflecting surface is part
(ii) A ray passing through
of a hollow sphere of glass.
the principal focus will
CONCAVE MIRROR become parallel to
reflecting surface is curved inwards, principal axis after
towards the center of the sphere reflection
CONVEX MIRROR
reflecting surface is curved outwards.
(iv) Ray incident at pole is
Pole (P): The center point of the reflected back making same
reflecting surface of a spherical angle with principal axis.
mirror.
CONCAVE MIRROR CONVEX MIRROR Sign Conventions for Spherical
Mirrors:
The object is always placed to the
left of the mirror.
Distances are measured from the
pole of the mirror.
Distances along the incident ray
(+X-axis) are positive, and those
against it (-X-axis) are negative.
Distances above the principal axis
are positive. Object distance = always +ve
Distances below the principal axis Focal length of concave mirror = -ve
are negative. Focal length of convex mirror = +ve
Important Formulas:
h’ = positive (virtual images)
h’ = negative (real images)
m = negative (real)
m = positive (virtual)
Magnification refers to the ratio of the height of an image
to the height of an object
Refraction of Light
Phenomenon of change in the
direction of light when it passes from
one transparent medium to another.
Laws of refraction of light.
(i) The incident ray, the refracted
ray and the normal to the
interface of two transparent media
at the point of incidence, all lie in
Uses of Concave Mirrors: the same plane.
Torches, Search-lights, and Vehicle Headlights:
Shaving Mirrors
Dentist's Mirrors Snell’s law of refraction.
Solar Furnaces
Uses of Convex Mirrors:
Rear-view Mirrors in Vehicles: Refractive index:
Preferred in Vehicles:
Provide erect, though diminished, images.
Have a wider field of view due to their outward curve. measurement of how much a light ray bends when it passes
Allow drivers to view a larger area compared to plane mirrors. from one medium to another.
Light the mirror's reflecting surface forms a part.
- Rectilinear propagation of light - light travels in a straight line. Radius of Curvature (R): The radius of the sphere of which
8
- Speed of Light = c = 3 x 10 m/s the mirror's reflecting surface forms a part. R=2f
Reflection: The bouncing back of light from any shiny surface Principal Axis: The straight line passing through the pole and
e.g. mirror or water. the center of curvature of the mirror.
The Laws of reflection Principal Focus (F): The point where parallel rays of light
states that: either converge or appear to diverge after reflecting from the
1. The Incident ray, the mirror.
Reflected ray and Focal Length (f): The distance between the pole and the
Normal all lie in the principal focus.
same plane.
Aperture: The diameter of the reflecting surface of the
2. Angle of incidence
spherical mirror.
(∠i) = The angle of
reflection (∠r). Ray Diagrams
(i) A ray parallel to principal
Plane mirror: A smooth and polished surface that reflects axis will pass through focus
light uniformly. after reflection.
The image formed by a plane mirror is :
always virtual and erect.
(iii) A ray passing through
size of the image is equal to that of the object.
center of curvature will
image formed is as far behind the mirror as the object is
follow the same path back
in front of it.
after reflection.
image is laterally inverted.
Spherical mirror: a mirror whose reflecting surface is part
(ii) A ray passing through
of a hollow sphere of glass.
the principal focus will
CONCAVE MIRROR become parallel to
reflecting surface is curved inwards, principal axis after
towards the center of the sphere reflection
CONVEX MIRROR
reflecting surface is curved outwards.
(iv) Ray incident at pole is
Pole (P): The center point of the reflected back making same
reflecting surface of a spherical angle with principal axis.
mirror.
CONCAVE MIRROR CONVEX MIRROR Sign Conventions for Spherical
Mirrors:
The object is always placed to the
left of the mirror.
Distances are measured from the
pole of the mirror.
Distances along the incident ray
(+X-axis) are positive, and those
against it (-X-axis) are negative.
Distances above the principal axis
are positive. Object distance = always +ve
Distances below the principal axis Focal length of concave mirror = -ve
are negative. Focal length of convex mirror = +ve
Important Formulas:
h’ = positive (virtual images)
h’ = negative (real images)
m = negative (real)
m = positive (virtual)
Magnification refers to the ratio of the height of an image
to the height of an object
Refraction of Light
Phenomenon of change in the
direction of light when it passes from
one transparent medium to another.
Laws of refraction of light.
(i) The incident ray, the refracted
ray and the normal to the
interface of two transparent media
at the point of incidence, all lie in
Uses of Concave Mirrors: the same plane.
Torches, Search-lights, and Vehicle Headlights:
Shaving Mirrors
Dentist's Mirrors Snell’s law of refraction.
Solar Furnaces
Uses of Convex Mirrors:
Rear-view Mirrors in Vehicles: Refractive index:
Preferred in Vehicles:
Provide erect, though diminished, images.
Have a wider field of view due to their outward curve. measurement of how much a light ray bends when it passes
Allow drivers to view a larger area compared to plane mirrors. from one medium to another.
