reflection of light by plane and spherical mirror use of spherical mirror and use of mirror formula .the presentation is very useful for class X students who studying physics

1. Presented By : Vasudev Shrivastava
P.G.T.(Physics)
Jawahar Navodaya Vidyalaya Nowgong District
Chhatarpur(M.P.)

2.  Light is a form of energy which provide
sensetation of vision of an object .
 Luminous objects – generate their own light
(the sun)
 Illuminated objects – reflect light (the moon)
 Line of Sight – a line from an object or image
to your eyes (light from the object travels
along this line to your eyes)
Slide 2

3.  Both luminous &
illuminated objects
emit/reflect light in
many directions.
 Your eye sees only
the very small
diverging cone of
rays that is coming
toward it.
Slide 3

4.  Incident Ray – leaves
the object and strikes
the mirror
 Reflected Ray – leaves
mirror and strikes
your eye
 The reflected ray is on
the line of sight from
the image to your eye.
Slide 4

5.  Angle of incidence equals
angle of reflection.
Slide 5

6.  Normal – line
perpendicular to the
mirror surface
 Angle of incidence – angle
between incident ray and
normal
 Angle of reflection – angle
between reflected ray and
normal
 Angle of incidence is
equal to angle of
reflection
 Incident ray reflected ray
and normal all lies on
same point.
Slide 6

7. qi = qr
Slide 7

8.  Regular reflection
:regular reflection : it
is when parallel rays of
light fall on a smooth
surface and reflect
parellely. irregular
reflection : it is when
parallel rays of light
fall on a rough surface
and reflect in different
directions
 The regular reflection
is due to smooth
surfaces like mirror .
Slide 8

9. Slide 9

10. Slide 10

11.  Driving at night on a wet roadway results in
an annoying glare from oncoming
headlights.
Slide 11

12.  The image formed by a
plane mirror is always
virtual (meaning that
the light rays do not
actually come from the
image), upright, and of
the same shape and
size as the object it is
reflecting. A virtual
image is a copy of an
object formed at the
location from which the
light rays appear to
come
Slide 12

13.  Image is virtual.
 Image is located as
far behind the mirror
as the object is in
front of the mirror.
 The size of image is
always equal to size
of object
Slide 13

14. Slide 14

15. Slide 15

16.  If the image of an
object is viewed in two
plane mirrors that are
inclined to each other
more than one image
is formed. The
number of images
depends on the angle
between the two
mirrors. The number
of images formed
n=(360/A)-1, if
(360/A) is even
integer.
Slide 16

17. Slide 17

18. Slide 18

19.  Angles smaller than
90o produce more
than 3 images
Slide 19

20. Slide 20

21.  Concave mirror
 Convex mirror
 Parboiled mirror

22.  If reflecting surface
of a mirror is
spherical then such a
mirrors is known as
spherical mirror
 Concave mirror
 Convex mirror
Slide 22

23.  Angle of Incidence is
equal to the angle of
reflection

24.  A series of flat mirrors
can be arranged to
reflect parallel light
through a single point.
 Increasing the number
of flat mirrors causes
the shape to more
closely approximate a
parabola and causes
the reflected light to
converge in a smaller
area.

25.  Close to the axis
of the mirror, the
parabola and the
circle are almost
the same shape.
 Farther from axis
the parabola
flattens out.
 It is easier and
less expensive to
make spherical
mirrors.

26.  A concave mirror is
silvered on the inside of
the sphere.
 A concave mirror is also
called a converging
mirror because it
converges parallel light.
 A convex mirror is
silvered on the outside
of the bowl.
 A convex mirror is also
called a diverging mirror
because it diverges
parallel light.

27.  Principal Axis
 Center of Curvature
 Radius of Curvature
 Focus
 Focal Length

28.  01 All distances are measure from pole.
 02 the direction of incident ray is taken to be
positive.
 03All the height above principal axis is taken to
positive and below the principal axis is taken to
be negative .
 04The object distance is always taken to be
negative.
 05 The focal length of convex mirror is
positive where the focal length of concave
mirror is negative .
Slide 28 mirrior is

29. Slide 29

30.  P pole of mirror
 F focus point
 C centre of
curvature
 f focal length
 R radius of
curvature
Slide 30

31.  01 Ray parallel to the
principal axis reflects
through the focus.
 02 Ray passes
through the focus
reflects parallel to
the axis.
 03 Ray passes
through the center of
curvature reflects
back on itself.

32.  1.) For a real object very far away from the
mirror, the real image is formed at the focus.
Slide 32

33. Slide 33

34. Slide 34

35. Slide 35

36. Slide 36

37. Slide 37

38. Slide 38

39. Slide 39

40. Slide 40

41. Slide 41

42.  01 when object located at infinity : The virtual
image will be drawn at focus of mirror and
size of image is small to the size of object.
Slide 42

43. Slide 43

44. Slide 44

45.  The distance between
the object and the pole
of the mirror is called
the object distance(u).
The distance between
the image and the pole
of the mirror is called
Image distance(v). The
distance between the
Principal focus and
pole of the mirror is
called Focal Length(f)
Slide 45

46.  01 the sign of u (object distance from mirror ) is
always negative.
 02 the sign of v (image distance from mirror) is
always negative for real image and positive for
virtual image .
 03 focal length of concave mirror is negative where
as for convex mirror it is positive .
 04 for real image the sign of m (magnification) is
negative ,for virtual image the sign of m is positive
 05 numerical value m greeter then 1 the image is
large in size , less then 1 small in size and if m is
equal to 1 then size of image and object both are
equal.
Slide 46

47.  Radius of curvature, R = + 3.00 m;
 Object-distance, u = – 5.00 m;
 Image-distance, v = ?
 Height of the image, h′= ?
 Focal length, f = R/2 = + 3.00/2= + 1.50 m
 Since 1/v+1/u = 1/f hence 1/v= 1/f- 1/(-)u
 1/v= 1/1.5+1/5 hence 1/v= (5+1.5)/7.5 = 6.5/7.5
 hence v= 7.5/6.5 = +1.15 hence image is virtual and
located behind the mirror at distance 1.15 m
 m = magnification = size of image/size of object= -(v/u)
 m = -(v/-u) = -(1.15/-5) = +.23 which is less then 1 so
that it small in size .
Slide 47

48. Slide 48

49. Slide 49

50.  Convex mirrors are commonly used as rear-view (wing)
mirrors in vehicles.
 Concave mirrors are commonly used in torches, search-lights
and vehicles headlights to get powerful parallel beams of
light. They are often used as shaving mirrors to see a larger
image of the face.
 The dentists use concave mirrors to see large images of the
teeth of patients
 Large concave mirrors are used to concentrate sunlight to
produce heat in solar furnaces.
Slide 50

51.  01Light seems to travel in straight lines.
 02Mirrors form images of objects. Images can be either real
or virtual, depending on the position of the object.
 03The reflecting surfaces, of all types, obey the laws of
reflection..
 04 New Cartesian Sign Conventions are followed for spherical
mirrors.
 05Mirror formula,1/f= 1/v+1/u , gives the relationship
between the object-distance (u), image-distance (v), and
focal length (f) of a spherical mirror.
 06 The focal length of a spherical mirror is equal to half its
radius of curvature.
 07 The magnification produced by a spherical mirror is the
ratio of the height of the image to the height of the object.
Slide 51

52.  01 If two plane mirror inclined on 900 with each others how many images can be
forms?
 02 If an object located 3 m from a plane mirror how much distance image is locate? ,
what is the nature of image?
 03 Find the focal length of a convex mirror whose radius of curvature is 32 cm.
 04A concave mirror produces three times magnified (enlarged) real image of an object
placed at 10 cm in front of it. Where is the image located?
 05Name the type of mirror used in the following situations.
 (a) Headlights of a car. (b) Side/rear-view mirror of a vehicle.
 (c) Solar furnace. Support your answer with reason.
 06 An object is placed at a distance of 10 cm from a convex mirror of focal length 15
cm. Find the position and nature of the image.
 07 . The magnification produced by a plane mirror is +1. What does this mean?
 08. An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex
mirror of radius of curvature 30 cm. Find the position of the image, its nature and
size.
 09. An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal
length 18 cm. At what distance from the mirror should a screen be placed, so that a
sharp focused image can be obtained? Find the size and the nature of the image.
Slide 52