1. OBJECTIVES
A. Predict the qualitative characteristics
(orientation, type, and magnification) of images
formed by plane and curved mirrors and
lenses.
B. Explain the uses of lenses and mirrors
3. Light is form of energy that you
can see! Every day, light waves reflect
on objects and into your eyes, which
allows you to see the objects. Light
also helps you identify objects both
near and far.
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4. Reflection of Light in Mirrors
The laws of reflection state that:
1. the incident ray, the reflected ray, and the
normal line to the reflecting surface all lie in
the same plane; and
2. the angle of incidence is equal to the angle of
reflection.
6. When light hits an object, every part of that object reflects
light in all direction. Some of the reflected light reaches our
eyes. Thus, we can see an object.
Characteristics of images formed by a plane mirror:
1. Image is virtual;
2. Same size as the object;
3. Same orientation as the object; and
4. Same distance from the mirror as the object.
Reflection in Plane Mirror
7. a. Specular/Regular reflection. It
is defined as light reflected from
a smooth surface at a definite
angle.
b. Diffused/Irregular Reflection. It
is produced by rough surfaces
that tend to reflect light in all
directions.
Types of Reflection of Light
(a) Mountains and its reflection on calm water
(b) Mountains and its reflection on wavy water
8. The phenomenon by which a ray of light changes
the direction of propagation when it strikes a boundary
between different media through which it cannot pass is
described as the reflection of light. If the bundle of light
rays is incident upon a smooth surface, then the light
rays reflect and remain concentrated in a bundle upon
leaving the surface. On the other hand, if the surface is
microscopically rough, the light rays will reflect and
diffuse in many different directions.
9.
10. If you view an image of yourself in a
plane mirror (perhaps a bathroom mirror),
you will quickly notice that there is an
apparent left-right reversal of the image. That
is, if you raise your left hand, you will notice
that the image raises what would seem to be
its right hand. If you raise your right hand, the
image raises what would seem to be its left
hand. This is often termed left-right reversal.
Mirror Left-Right Reversal
11. The letters in front of the
ambulance are written laterally.
This is because when seen in rear
view mirror by another vehicle, the
image of the word would get
inverted, letting the driver read the
word properly so that he can
provide way to the ambulance.
12. Most curved mirrors are called spherical mirrors because
their shape follows the surface of a sphere.
Reflection on Spherical Mirrors or curved mirrors
13. 1. The Concave Mirror
It reflects light inward to one focal point. It is
used to focus light.
Also known as converging mirror which has a
reflecting surface that is recessed inward.
Two Kinds of Spherical Mirrors:
14. 2. The Convex Mirror
Also known diverging mirror. It is a curved
mirror in which the reflective surface bulges
towards the light source.
Convex mirrors reflect light outwards; therefore
they are not used to focus light.
Two Kinds of Spherical Mirrors:
17. Applications of Concave and Convex Mirrors
Mirrors are part of our everyday life. We
regularly use plane mirror in checking our
physical appearance every morning before we
leave our homes. There are mirrors found in
our vehicles. While driving we use different-
shaped mirrors to check on the position of
vehicles on the next lane.
18. When these plane mirrors are placed next to
each other at an angle, it gives our eyes not
only one image, not even two but more than
that. This is called multiple images. The
mechanism of multiple images is used in the
fun and colorful kaleidoscope.
19. Concave mirror
Concave mirror, also known as a
converging mirror has reflecting
surface which collects light inward
and focus them to one focal point, this
type of mirror is what the dentist used
in magnifying the area behind your
teeth to check on cavities and tooth
decay.
20. For illuminating purposes, you can
see concave mirrors used in
headlamps, flashlights and
spotlights. In these devices, the light
rays that gathered from a small
source of the mirror are collected and
directed outward in a beam. Small
light source bounded by a concave
mirror flashes a brighter beam.
21. Convex mirror
Convex mirror has a wider view field compared to a
concave mirror. This makes bigger objects appear to
be smaller than their original form. A car’s side
mirrors enable the driver and its passenger to see
the vehicles behind. Also, while in mall
supermarkets and in some convenience stores, you
may notice mirrors hanging on corners from which
you can see your reflection and those of other
people. These are just some of the applications of
convex mirrors.
23. Let us talk about another object which plays a
vital role in the study of the behavior of light,
lenses. Like the mirror, the lens is usually made
of glass. The only thing that makes it different is
that the lens can also be made of other
transparent materials like plastics that allow
light to pass through, instead of bouncing the
light rays off.
24. Uses of Convex Lenses
a convex lens is characterized by its bulging
surfaces that is directed outward making it
thicker at the center than on its edges.
25. Uses of Convex Lenses
Image produced by convex lenses can be a
virtual or real image. If both sides of the lens
are curved outward, then that type of convex
lens is called biconvex typically seen in
magnifying glasses. If only one side of the lens
is curved outward and the other has a flat
surface, it is called as plano-convex
27. Microscopes
Among the applications in which
convex lenses are used is found in
compound microscopes. A
microscope is an instrument that is
used in viewing small objects and
microorganisms that are impossible
for our unaided eyes to see. It uses
lenses that can magnify objects100x
or even more than a thousand times.
29. CAMERA LENSES
camera uses convex lenses where light rays pass
through. These light rays are directed towards the
slanted mirror located near the camera shutter, and
then reflected from a translucent screen projected to
another mirror until it reaches the viewer’s eye.
30. The Human Eye is a Natural Camera
Our eyes are our natural cameras. Some of the basic
and fundamental parts of a camera functions just like
how the different parts of our eyes work. Among these
are the lens, the aperture, iris diaphragm, shutter, and
photographic film. The lens, just like the cornea of our
eyes gathers and bends light rays inwardly to the
camera.
31. The Human Eye is a Natural Camera
The iris diaphragm controls the size of the aperture
(opening) to regulate the light that enters. This duo
resembles the iris and the pupil of our eyes. The shutter
opens and shuts the aperture to avoid too much light
exposure thus helping the photographic film capture a
beautiful image similar to the work done by the eyelids
and the retina.
32. Concave Lens
Contrary to concave lens, convex lens has thicker edges curving towards
the center, causing light to diverge, hence it is called as the diverging lens.
It spreads out light, producing virtual image, making object to appear
smaller and farther than the way it actually is. Although convex lenses can
magnify object, it still cannot transfer light accurately that’s why an object
would appear blurry, so makers of binoculars and telescopes add concave
lens to these instruments in order to focus objects that are too far for our
eyes to see.
33. Concave Lenses and Myopia (nearsightedness) Correction
Concave lenses, such as eyeglasses and contact
lenses are used in correcting myopia
(nearsightedness). Myopia is a condition in which
light rays focus in front. The Human Eye and a
Camera 13 the eye’s retina instead of, on the retina.
The result of this condition is a makes distant object
to appear blurry, while near objects appear normal.
34. Meniscus Lenses and Hyperopia (farsightedness) Correction
Hyperopia is the eye condition that enables someone to see distant
object clearly but makes nearby object seem blurry. This condition is
due to the inability one’s eyes to focus on objects closer to the eyes. A
person with hyperopia has a shortened eyeball, in which the retina lies
closer than usual to the cornea and lens. This disorder leads to the
formation of the image nearby object to form beyond retina. Hyperopia
is the opposite of myopia, another vision problem that needs
correction. To correct hyperopia, converging meniscus converging lens
is used. The converging meniscus lens converge light before it enters
the eye eventually reducing the image distance.
