8

Science
Reflection and
Refraction of Light
Name: _______________________________ Date: __________________

QUALITATIVE CHARACTERISTICS OF IMAGES

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.

What’s In
In Grade 7, 8, and in the previous modules, you learned about electromagnetic
spectrum. One of the most common among these electromagnetic waves is the visible light.
Let us start our study of this module by reviewing first the properties and behavior of light
when it meets something.

Directions: Fill in the blanks in the sentence below. Below each paragraph are words
corresponding on the properties and behavior of light that you will encounter in this module.
Write your answer on a clean sheet of paper.

Light is a natural agent that stimulates sight and make things possible. It is a type of
energy known as 1. ___________. It is given out by luminous objects such as the sun, light
bulbs and laser. It is made up of little packets of energy called 2.___________. Light travels
as waves. But unlike sound waves, it does not need any material to carry its energy along.
This means that light can travel through a 3. ____________ - a completely airless space.
Light waves travel out from their source in a straight line called 4. __________.

Electromagnetic radiation photons rays vacuum

Light behaves in a variety of ways when it meets water, air, and other matters. When
light strikes matter, a part of light is 5“__________” into the matter and is transformed into
heat energy. If the matter that the light strikes is a transparent material, the light component
that was not absorbed within the material is
6. “__________” through and exits to the outer side of the material. If the surface of the
material is smooth (a mirror for example), 7.“_________” occurs, but if the surface is irregular
having pits and protrusions, the light 8. “__________”.
Absorbed reflection scatters transmitted
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.

incident ray- the Reflected ray-

ray of light the ray of light
coming from the perpendicular to the which leaves
light source surface the mirror
towards a
surface Angle of
incidence Angle of
reflection
angle of Angle of
incidence-the reflection- the
angle between angle between
the incident ray the reflected ray
and normal line and normal line
Reflection in Plane Mirror
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.

Figure3. Reflection in a plane Mirror

Types of Reflection of Light

a. Specular/Regular reflection.
It is defined as light reflected from a smooth
surface at a definite angle.

a) Mountains and its reflection on calm water

b. Diffused/Irregular Reflection.
It is produced by rough surfaces that
tend to reflect light in all directions.

(b) Mountains and its reflection on wavy water

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.

Specular Reflection Diffuse Reflection

(smooth surface) (rough surface)
Figure 5. (a) Parallel light rays reflect in one direction. (b) Parallel light rays reflect in different
directions.
Mirror Left-Right Reversal
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.

Figure 6. Mirror Left-Right Reversal

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.

Reflection on Spherical Mirrors

Most curved mirrors are called spherical mirrors because their shape follows the
surface of a sphere.
Two Kinds of Spherical Mirrors:
1. The Concave Mirror
 It reflects light inward to one focal point.
It is used to focus light.
 Also known as converging mirror has
a reflecting surface that is recessed inward
(away from the incident light).
Figure 9.Parallel rays converge after reflection on a concave
mirror

2. The Convex Mirror

 Also known diverging mirror 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.
Figure 10.Parallel rays diverge after reflection on a
convex mirror

There are two types of images formed by reflecting surfaces.

 Figure 11. Reflection from Concave And Convex Mirror

Virtual Image
1.A virtual image is formed when light
rays do not actually intersect after
reflection, but they appear to diverge
from the mirror.
a 2.A virtual image cannot be formed
on a screen.
3. A virtual
. image is erect with respect
to the object
e.g. The image of an object formed by
a convex mirror.

Enrichment Activity 2 “Mirror Left-Right Reversal”

1. Stand in front of a plane mirror.

2. Raise your left hand.
Assessment 1
Direction: Answer the following questions on your answer
sheet.
1. Is your image exactly the same size as you are?
A. image is exactly the same B. image is virtual
2. What hand does your image raise?
A. right hand B. left hand
3. Is your image erect or inverted? Is it real or virtual?
A. inverted, real B. erect, virtual

Enrichment Activity 2 “Image Formed by Curved Mirrors”

1.Get a spoon. This can serve as your mirror.
2. Look at the concave surface of the spoon.
Place the mirror vey near your face.
3. Bring the spoon on arm length distance
away from you.
4. Look now at the convex surface of the spoon.
Observe your image as you bring the spoon
farther form you. Image from the
Image from the
outer side of the inner side of the
spoon spoon
Assessment 2
Fig.15 Image in Spherical Mirror
Directions: Answer the following questions. Use a separate sheet.
1. Describe your image as you look at your face on the concave surface of the spoon.
A. erect, virtual B. inverted, real
2. Describe your image after you bring the spoon on arm length distance away from you
using the concave surface of the spoon.
A. appear as real image B. appear as virtual image

What I Have Learned

Great job! You are almost done with this module. Let’s summarize what you have
learned from the lesson and activities by answer the following in a separate sheet.
A. Below are the qualitative characteristics of images. Determine whether it is REAL or
VIRTUAL type of images:
1.___________is upright.
2.___________is inverted.
3.___________is behind the mirror
4.___________is formed by convex mirror.
5. ___________can be projected onto a screen
6.____________is inverted with respect to the object
7. __________is on the same side of the mirror as the object
8.__________rays of light do not actually pass through the image
9.__________ can be larger, smaller, or the same size as the object
10. _________rays of light actually converge and pass through the

B. Identify whether the following is PLANE, CONCAVE or a CONVEX MIRROR

1.________forms images that are either behind the mirror or on the same side as the object.
2.________forms images that are always the same distance from the mirror as the object.
3._______forms images that are smaller/same size/larger than the object.
4._______forms images that are the same size as the object only.
5._______forms images that have left to right reversal.
6._______forms images that are either real or virtual.
7._______forms images that are upright or inverted.
8. _______forms images that are behind the mirror.
9._______forms images that are always reduced.
10.______forms images that are always upright.
11. ______forms images that are only virtual.
12.______forms real or virtual images.
13.______forms only virtual images.
14.______ is flat, smooth mirror.
15.______ is a curved mirror.

What I Can Do
Think whether the given objects below act as a CONCAVE or CONVEX.
Number Object Types of Mirror
1.Vehicle glass mirror
2.Water glass surface
3.Head light of motorcycle
4.Tube lights
5.Inner surface glasses
6. Lunch plates
7.Calling bells
8.Surface pens
9.Globes
10.Surface of steel flask
Assessment
Posttest
Directions: Read carefully each item. Choose the letter that you think best answers the question. Write the
answer in your notebook or sheet of paper.
1. The reflection by the rough surfaces that tend to reflect light in all directions is called _______________ .
a. diffused reflection c. regular reflection
b. glossy reflection d. specular reflection
2. The image you see in a plane mirror is called a _______________ image because it is not a real, physical
object.
a. imaginary b. physical c. reflected d. virtual
3. The image seen in a plane mirror is ______________.
a. real and inverted c. virtual and inverted
b. real and upright d. virtual and upright
4. Diffuse Reflection is produced by _______________ surfaces that tend to reflect light in all directions.
a. rough b. semi rough c. semi smooth d. smooth
5. Which of the following is a diverging lens?
a. concave lens b. convex lens c. parabolic lens d. plane lens
6. If the angle of incidence between the incident ray and the normal line is 25 degrees, what is the angle of
reflection?
a. 65 degrees b. 45 degrees c. 35 degrees d. 25 degrees
7. The image formed by a concave mirror will ______________.
a. always be real c. be either real or virtual
b. always be virtual d. will always be magnified
8. The image formed by a convex mirror will _______________ .
a. always be real c. be either real or virtual
b. always be virtual d. will always be magnified
9. A spherical mirror with reflecting surface curved inwards is called ________.
a. concave mirror c. curved mirror
b. convex mirror d. none of the above