Grade 10 science

2. • Lesson 1 – Plane
Mirror
• Lesson 2 – Mirrors:
Concave and
Convex
• Lesson 3 – Lenses:
Concave and
Convex

3. Predict the qualitative characteristics
(orientation, type, and magnification) or
images formed by plane and curved mirrors
and lenses.
MELC

4. Reflection is a fundamental property of
light, and it refers to the bouncing back of
light when it encounters a surface.
Reflection Properties of Light

5. SPECULAR VS DIFFUSE
TYPES OF REFLECTION
Light reflects from a smooth surface at the
same angle as it hits the surface. For a
smooth surface, reflected light rays travel
in the same direction. This is called
specular reflection. For a rough surface,
reflected light rays scatter in all directions.
This is called diffuse reflection.

6. The angle of incidence (the angle between the incident ray and the normal, which is
an imaginary line perpendicular to the surface) is equal to the angle of reflection
(the angle between the reflected ray and the normal). This principle is known as the
Law of Reflection and holds true for smooth surfaces.

7. Incident Ray
The incident ray is the incoming ray of light that strikes the
surface.
Normal Line
The normal line is an imaginary line drawn perpendicular to
the surface at the point of incidence. The angles of
incidence and reflection are measured relative to this line.

8. Angle of Incidence and
Reflection
The angles of incidence and reflection are measured with
respect to the normal line, providing a consistent way to
describe the reflection process
Reflected Ray
The reflected ray is the ray of light that bounces off the
surface.

9. Multiple Reflections
Multiple reflections occur
when light reflects more
than once, such as in a
series of mirrors arranged
at different angles

10. How do mirrors
interact with
light?

11. Converging and
Diverging
Mirrors

12. Which is which?

13. Converging vs Diverging Mirror

14. Converging vs Diverging Mirror
A converging mirror focuses light rays to a point, while a diverging
mirror spreads them out.

15. Converging vs Diverging Mirror
Converging mirrors, also known as
concave mirrors, have a curved surface
that bulges inward. When light rays hit
the mirror, they are reflected inward and
converge at a point called the focal point.
The distance between the mirror and the
focal point is called the focal length.
Converging mirrors are commonly used in
telescopes, cameras, and headlights.

16. Converging vs Diverging Mirror
Diverging mirrors, also known as convex
mirrors, have a curved surface that bulges
outward. When light rays hit the mirror,
they are reflected outward and diverge, or
spread out. The focal point of a diverging
mirror is imaginary, as the reflected rays
never actually converge. Diverging mirrors
are commonly used in rear-view mirrors
and security mirrors.

17. Converging vs Diverging Mirror
The difference between converging and diverging mirrors lies in
their curvature and the way they reflect light. Converging mirrors
focus light rays to a point, while diverging mirrors spread them
out. This difference in reflection is due to the different shapes of
the mirrors. Converging mirrors have a concave shape, while
diverging mirrors have a convex shape. Understanding the
properties of converging and diverging mirrors is important in the
study of optics and the design of optical instruments.

18. The Anatomy of
a Curved Mirror

19. If a concave mirror is thought of as a slice of
a sphere, where is the principal axis located?
A. At the vertex
B. At the center of curvature
C. At the midpoint of the center of curvature
and the vertex
D. At the focal point

20. What is denoted by the letter C in the
diagram of a concave mirror?
A. Center of curvature
B. Principal axis
C. Focal point
D. Vertex

21. Which point on the concave mirror's surface
is denoted by the letter A in the diagram?
A. Center of curvature
B. Principal axis
C. Vertex
D. Focal point

22. The focal length of a concave mirror is:
A. Equal to the radius of curvature
B. One-half the radius of curvature
C. Equal to the distance between the vertex
and the center of curvature
D. Equal to the distance between the vertex
and the focal point

23. What is the distance from the mirror to the
focal point known as?
A. Radius of curvature
B. Focal length
C. Vertex
D. Principal axis

24. If the focal point is the midpoint between the vertex
and the center of curvature, what is the relationship
between the focal length and the radius of
curvature?
A. They are equal
B. The focal length is greater than the radius of
curvature
C. The focal length is less than the radius of curvature
D. The focal length is one-half the radius of curvature

25. How is the line passing through the center of
the sphere and attaching to the mirror in the
exact center of the mirror referred to?
A. Vertex
B. Principal axis
C. Center of curvature
D. Focal point

26. Which point is the geometric center of the
concave mirror?
A. Center of curvature
B. Principal axis
C. Vertex
D. Focal point

27. In which location would the center of
curvature of a concave mirror be found?
A. At the focal point
B. At the vertex
C. On the principal axis
D. On the mirror's surface

28. What is represented by the distance from the
vertex to the center of curvature in a
concave mirror?
A. Principal axis
B. Focal length
C. Radius of curvature
D. Center of curvature

29. 1.) C. At the midpoint of the center of curvature and
the vertex
2.) A. Center of curvature
3.) C. Vertex
4.) B. One-half the radius of curvature
5.) B. Focal length
6.) D. The focal length is one-half the radius of
curvature
7.) B. Principal axis
8.) C. Vertex
9.) C. On the principal axis
10.) C. Radius of curvature

30. Spherical Mirrors
Curved mirrors that have a spherical
shape are called spherical mirrors. It
can be thought of as a portion of a
sphere that was sliced away and then
silvered on one of the sides to form a
reflecting surface. Concave mirrors
were silvered on the inside of the
sphere and convex mirrors were
silvered on the outside of the sphere.

31. Ray Diagramming Technique
If a concave mirror were thought of
as being a slice of a sphere, then
there would be a line passing
through the center of the sphere
and attaching to the mirror in the
exact center of the mirror. This line
is known as the principal axis.

32. Ray Diagramming Technique
The point in the center of the
sphere from which the mirror was
sliced is known as the center of
curvature and is denoted by the
letter C in the diagram. The point on
the mirror's surface where the
principal axis meets the mirror is
known as the vertex and is denoted
by the letter A in the diagram.

33. Ray Diagramming Technique
The vertex is the geometric center of
the mirror. Midway between the
vertex and the center of curvature is
a point known as the focal point; the
focal point is denoted by the
letter F in the diagram. The distance
from the vertex to the center of
curvature is known as the radius of
curvature (represented by R).

34. Ray Diagramming Technique
The radius of curvature is the radius
of the sphere from which the mirror
was cut. Finally, the distance from
the mirror to the focal point is known
as the focal length (represented
by f). Since the focal point is the
midpoint of the line segment
adjoining the vertex and the center of
curvature, the focal length would be
one-half the radius of curvature.

35. What is the Focal Point?
The focal point is the point in space
at which light incident towards the
mirror and traveling parallel to the
principal axis will meet after
reflection. The diagram at the right
depicts this principle. In fact, if some
light from the sun were collected by
a concave mirror, then it would
converge at the focal point.

36. What is the Focal Point?

37. Images formed by
concave mirrors

38. Let us RECALL
Light always follows the law of reflection, whether the
reflection occurs off a curved surface or off a flat surface.
The task of determining the direction in which an incident
light ray would reflect involves determining the normal to
the surface at the point of incidence. For a concave mirror,
the normal at the point of incidence on the mirror surface is
a line that extends through the center of curvature. Once
the normal is drawn the angle of incidence can be
measured and the reflected ray can be drawn with the
same angle.

39. Let us RECALL
At the point of incidence
where the ray strikes the
mirror, a line can be drawn
perpendicular to the
surface of the mirror. This
line is known as a normal
line. The normal line divides
the angle between the
incident ray and the
reflected ray into two
equal angles.

40. Images formed by concave mirrors
Depending on the object location, the image could be
enlarged or reduced in size or even the same size as the
object; the image could be inverted or upright; and the
image will be in a specific region along the principal axis.

41. Two Rules of Reflection for Concave Mirrors
Light always reflects according to the
law of reflection, regardless of
whether the reflection occurs off a
flat surface or a curved surface. Using
reflection laws allows one to
determine the image location for an
object. The image location is the
location where all reflected light
appears to diverge from. Thus, to
determine this location demands that
one merely needs to know how light
reflects off a mirror.

42. The two rules of reflection for concave mirrors:
• Any incident ray traveling
parallel to the principal axis
on the way to the mirror will
pass through the focal point
upon reflection.
• Any incident ray passing
through the focal point on
the way to the mirror will
travel parallel to the principal
axis upon reflection.

43. Step-by-Step Method for Drawing Ray Diagrams
1. Pick a point on the top of the object
and draw two incident rays traveling
towards the mirror.
Using a straight edge, accurately draw
one ray so that it passes exactly
through the focal point on the way to
the mirror. Draw the second ray such
that it travels exactly parallel to the
principal axis. Place arrowheads upon
the rays to indicate their direction of
travel.

44. Step-by-Step Method for Drawing Ray Diagrams
2. Once these incident rays strike the mirror, reflect them
according to the two rules of reflection for concave mirrors.
The ray that passes through the focal point on the way to the
mirror will reflect and travel parallel to the principal axis. Use a
straight edge to accurately draw its path. The ray that traveled
parallel to the principal axis on the way to the mirror will reflect
and travel through the focal point. Place arrowheads upon the
rays to indicate their direction of travel. Extend the rays past their
point of intersection.

45. Step-by-Step Method for Drawing Ray Diagrams
3. Mark the image of the top of the object.
The image point of the top of the object is the point where the
two reflected rays intersect. If your were to draw a third pair of
incident and reflected rays, then the third reflected ray would also
pass through this point. This is merely the point where all light from
the top of the object would intersect upon reflecting off the
mirror. Of course, the rest of the object has an image as well and
it can be found by applying the same three steps to another
chosen point.

46. Step-by-Step Method for Drawing Ray Diagrams
4. Repeat the process for the bottom of the object.
The goal of a ray diagram is to determine the location, size,
orientation, and type of image that is formed by the concave
mirror. Typically, this requires determining where the image of the
upper and lower extreme of the object is located and then
tracing the entire image. After completing the first three steps,
only the image location of the top extreme of the object has
been found. Thus, the process must be repeated for the point on
the bottom of the object.

47. Image Formation for CONCAVE Mirrors

48. Image Formation for CONCAVE Mirrors

49. Let’s Practice

50. Let’s Practice

57. Images formed by
convex mirrors

63. Image Formation
In the animation above, an
object is positioned above the
principal axis of a concave
mirror and somewhere beyond
the center of curvature (C). The
concave mirror will produce an
image of the object which is
inverted (positioned below the
principal axis) and located
between the center of
curvature (C) and the focal
point (F) of the mirror.

64. Image Formation
Any person viewing this image
must sight at this image
position. The animation depicts
the path of light to each
person's eye. Different people
are sighting in different
directions; yet each person is
sighting at the same image
location. As seen in the
animation, the image location
is the intersection point of all
the reflected rays.

65. Image Formation
In the animation above, an
object is positioned above the
principal axis of a concave
mirror and between the center
of curvature (C) and the focal
point (F). The concave mirror
will produce an image of the
object which is inverted
(positioned below the principal
axis) and located somewhere
beyond the center of curvature
(C) of the mirror.

66. Image Formation
Any person viewing this image
must sight at this image
position. The animation depicts
the path of light to each
person's eye. Different people
are sighting in different
directions; yet each person is
sighting at the same image
location. As seen in the
animation, the image location
is the intersection point of all
the reflected rays.

67. The Anatomy of the
Lens

68. What is a lens?
If a piece of glass or other
transparent material takes on
the appropriate shape, it is
possible that parallel incident
rays would either converge to
a point or appear to be
diverging from a point. A piece
of glass that has such a shape
is referred to as a lens.

69. Types of Lenses
Lenses differ from one another in terms of their shape and the
materials from which they are made.

70. Types of Lenses
A converging lens is a lens that
converges rays of light that are traveling
parallel to its principal axis. Converging
lenses can be identified by their shape;
they are relatively thick across their
middle and thin at their upper and lower
edges.

71. Types of Lenses
A double convex lens is symmetrical
across both its horizontal and vertical
axis. Each of the lens' two faces can be
thought of as originally being part of a
sphere. The fact that a double convex
lens is thicker across its middle is an
indicator that it will converge rays of light
that travel parallel to its principal axis. A
double convex lens is a converging lens.

72. Types of Lenses
A diverging lens is a lens that diverges
rays of light that are traveling parallel to
its principal axis. Diverging lenses can
also be identified by their shape; they
are relatively thin across their middle and
thick at their upper and lower edges.

73. Types of Lenses
A double concave lens is also
symmetrical across both its horizontal
and vertical axis. The two faces of a
double concave lens can be thought of
as originally being part of a sphere. The
fact that a double concave lens is
thinner across its middle is an indicator
that it will diverge rays of light that travel
parallel to its principal axis. A double
concave lens is a diverging lens.

74. The Language of Lenses
If a symmetrical lens were thought of as being a slice of a sphere, then there would be a line
passing through the center of the sphere and attaching to the mirror in the exact center of the
lens. This imaginary line is known as the principal axis. A lens also has an imaginary vertical axis
that bisects the symmetrical lens into halves. As mentioned above, light rays' incident towards
either face of the lens and traveling parallel to the principal axis will either converge or diverge.
If the light rays converge (as in a converging lens), then they will converge to a point.

75. The Language of Lenses
This point is known as the focal point of the converging lens. If the light rays diverge (as in a
diverging lens), then the diverging rays can be traced backwards until they intersect at a point.
This intersection point is known as the focal point of a diverging lens. The focal point is denoted
by the letter F on the diagrams below. Note that each lens has two focal points - one on each
side of the lens. Unlike mirrors, lenses can allow light to pass through either face, depending on
where the incident rays are coming from. Subsequently, every lens has two possible focal
points.

76. The Language of Lenses
The distance from the mirror to the focal point is known as the focal length (abbreviated by f).
Technically, a lens does not have a center of curvature (at least not one that has any
importance to our discussion). However a lens does have an imaginary point that we refer to as
the 2F point. This is the point on the principal axis that is twice as far from the vertical axis as the
focal point is.