Lights lesson plan

Mabolo Christianacademy
13 C,Borces Street,Mabolo,6000 Cebu City
OBJECTIVES:
At the end of the lesson the students should be able to:
Competencies :
 Demonstrate the existence of the color components of visible light using a prism or diffraction grating
 Explain the hierarchy of colors in relation to energy;
 Explain that red is the least bent and violet the most bent according to their wavelengths or frequencies
Objectives:
 Describe refraction.
 Use refraction to explain apparent changes of the positions of things we see.
 Describe the behavior
 Infer that: (a) white light is made up of many different colors of light ,and (b) each of these colors of light bends
differently when it strikes objects like a prism.
 Infer energy of the colors of light increases as one goes towards the right side of the color spectrum;red light has
the least energy and violet light has the most energy.
 Infer that: light is composed of colors of different frequencies and wavelength; the frequencies of the colors of light
are inversely proportional to the wavelength; the arrangement of colors of light shows the hierarchy of the color’s
corresponding energy.
I. SUBJECT MATTER:
Topic: LIGHT
Sub-topic: REFRACTION OF LIGHT RAYS, DISPERSION, COLORS IN RELATION TO ENERGY,AND
REFRACTIVE INDEX OF THE COLOR OF LIGHT
Reference: Science Learner’s Module
You and the Natural World Science
General Science 8 by Jauco et al
Science 8 by Bautista et al
Materials: PROJECTOR/TV,SPEAKER,LAPTOP
Value Focus: Active Participation,Carefulness,Too much exposure to gadgets may harm our health.
II. LEARNERS’ EXPECTATIONS:
A. Activity
 How do sound waves reflect and refract?
 Light exhibits the characteristics and properties of a wave. Light tends to travel in a straight line,
unless it is acted on by some external force or condition. "What kinds of forces or conditions can
affect light, and how?" To answer this question, we start with what we can see in everyday life.
from each other.
 Why do our finger look swollen or big when we dip it into the water?Ask the students if they know
the meaning of work. Emphasize to them that the meaning /definition of work and the one that we
use in Science are quite different.
 Describe the behavior of light as it passes from one medium to another.
 What do you see in the picture?
 Are you fond of rainbow hunting?
 Have you ever wondered how rainbow appears in a clear sky?
 How rainbow form and what are the colors of the rainbow?
 Describe the position of the different colors after passing through the prism.
 Why do you think we tend objects as having fixed colors?
 For example, an apple is red. In reality, an object’s appearance results from the way it
reflects the particular light that is falling on it. Under white light, the apple appears red
because it tends to reflect light in the red portion of the spectrum and absorb light.

 Which colors of light has the least energy? Most energy?
 Study and analyze the pictures of the stars at night.
 Do you think they have the same energy? Explain your answer.
B. Analysis
1. List and arrange the observed colors according to how
they appear on the paper.
2. Describe the position of the different colors after passing
through the prism
3. Explain the dispersion of white light. Why is the prism or
water able to separate the colors of white light?
4. Compare your results in the first part with your results in
the second part. Are there any differences?
What might account for the differences?
5. What did you observe with the indices of refraction of the
colors of light in the acrylic prism?
6. How would this indices of refraction account for the
arrangement of colors of light?
7.Which thermometer registered the lowest temperature?
8.. Which thermometer registered the highest temperature?
9.. Which colored plastic allowed more energy to pass through it?
10. Which colored plastic allowed the least energy to pass through it?
11.. From your answers in 3 and 4, which color of light has the least energy? The most energy?
12.Which color registered the highest frequency? shortest wavelength?
13. Which color registered the lowest frequency? longest wavelength?
14. What did you observe about the wavelengths and frequencies of the different colors of light?
15. What did you observe about the products of frequencies and wavelengths?
16. Does the frequencies of the colors of light increase from red to violet?
17. What did you observe about the corresponding energies from red to violet?
18.How is frequency relate to energy of colors of light?
C. Abstraction
 When driving on a black road on a hot day, you may see what appear to be a puddle of water up ahead of you.
But when you get there, it is dry. Why?
 What is this phenomenon called? (a mirage)
 Light travels in a straight line. This is so as long as long as the medium in which it is traveling is uniform all
throughout. When light crosses a boundary between two transparent media of different optical densities, light
bends. The bending of light due to change in its speed is called refraction. When light travels from air to water, the
speed of light decreases because the optical density of water is greater than air.

 Light travels in a straight line. This is so as long as long as the medium in which it is traveling is uniform all
throughout. When light crosses a boundary between two transparent media of different optical densities, light
bends. The bending of light due to change in its speed is called refraction. When light travels from air to water,
the speed of light decreases because the optical density of water is greater than air.
 In figure 3, θi is the angle of incidence and θr is the angle of refraction (the angle between the outgoing ray, in the
medium, and the normal to the boundary).

 As light enters an optically more dense material, the angle of refraction is smaller than the angle of incidence-the
light bends toward the normal. Likewise, if light passes from an optically dense medium to a less dense
medium, the light bends away from the normal.
 A known indicator of the optical density of a material is the index of refraction of the material. Index of
refraction represented by the symbol n is the ratio of the speed of light in vacuum and its speed in
another medium. In symbols;
 n= speed of light in a vacuum speed of light in material
 The ratio is always greater than 1. For water, n is usually equal to 1.360 while air is more or less
comparable to vacuum so its n is 1.000.
 In figure 3, θi is the angle of incidence and θr is the able of refraction (the angle between the outgoing ray,
in the medium, and the normal to the boundary).
 As light enters an optically more dense material, the angle of refraction is smaller than the angle of
incidence-the light bends toward the normal. Likewise, if light passes from an optically dense medium to a
less dense medium, the light bends away from the normal.
 A known indicator of the optical density of a material is the index of refraction of the material. Index of
refraction represented by the symbol n is the ratio of the speed of light in vacuum and its speed in
another medium. In symbols;
 n= speed of light in a vacuum speed of light in material
 The ratio is always greater than 1. For water, n is usually equal to 1.360 while air is more or less
comparable to vacuum so its n is 1.000.

Upon passage through the prism, the white light is separated into its component colors - red, orange,
yellow, green, blue and violet. The separation of visible light into its different colors is known as dispersion.
Dispersion is a special kind of refraction which provided us colors of light. It occurs whenever there is a process
that changes the direction of light in a manner that depends on wavelength. Dispersion can occur for any type
of wave and always involves wavelength-dependent processes. For a given medium, n increases as
wavelength decreases and is greatest for violet light. Thus violet light is bent more than red light, as can
be seen with a prism. Refer to the figure below.
In a rainbow, light enters a drop of water and is reflected from the back of the drop. The light is refracted
both as it enters and as it leaves the drop.
Figure 1. Dispersion of white light into bands of colors

The formation of a rainbow involves a series of physical phenomena - reflection,
refraction, dispersion and total internal reflection. The occurrence of each of these is due
to the interaction of light with air and water and the boundaries between them.
Explain the following:
1. Why the sky is blue?
The sky appears blue because of the scattering of blue and violet light from the sunlight in the
atmosphere. Violet light is more scattered than blue light; however, our eyes are most sensitive to blue,
thus we see a blue sky.
2. Why the sunset is red?
During sunset, the path through which the light travels in the atmosphere becomes longer. As a
consequence, more blue and violet are scattered from sunlight. Thus, less blue light reaches the ground
and the light that reaches the Earth’s surface is red.
3. Why the clouds are white?
Clouds are made up of cluster of water droplets of different sizes. Since the color
of scattered light depends on the size of the particles, the different-size clusters
scatter a variety of colors. The smallest clusters scatter blue light resulting in blue
clouds; the medium-sized cluster make green and the larger ones make red. The
combination of these result in white cloud
Energy is directly proportional to the frequency of the light. The list of colors goes from low frequency to high
frequency. Red Orange Yellow Green Blue Indigo Violet. Red has the lowest frequency, so red has the lowest
energy. Violet has the highest frequency, so violet has the highest energy.
Our eyes are sensitive to light which lies in a very small region of the electromagnetic spectrum labeled "visible light". This
"visible light" corresponds to a wavelength range of 400 - 700 nanometers (nm) and a color range of violet through red.
The human eye is not capable of "seeing" radiation with wavelengths outside the visible spectrum. The visible colors from
shortest to longest wavelength are: violet, blue, green, yellow, orange, and red. Ultraviolet radiation has a shorter
wavelength than the visible violet light. Infrared radiation has a longer wavelength than visible red light. The white light is a
mixture of the colors of the visible spectrum. Black is a total absence of light.
The effects of colored light on people have been studied bypsychologists. They found out that people do show varied
responses to different colors. Colors influence a person’s emotion and degree of activity.
According to psychologists:
1. Red light/color may bring about a rise in blood pressure,
respiration rate, and frequency of blinking. It excites people.
2. Blue light/color produces effects opposite to those red light;
hence, it lessens activity.
3. Purple has a mournful effect.
4. Yellow is joyful and green has a peaceful effect.
Knowing all these, would you:
a. choose red paint/wall paper for your bedroom?
b. wear black during summer?
c. wear light colored shirt during cold days
What is the relationship between wavelength, frequency and energy?
The greater the energy, the larger the frequency and the shorter (smaller) the wavelength. Given the relationship
between wavelength and frequency — the higher the frequency, the shorter the wavelength — it follows that short
wavelengths are more energetic than long wavelengths.
How are temperature and color related?

The amount of light produced at each wavelength depends on the temperature of the object producing the light.
Stars hotter than the Sun (over 6,000 degrees C) put out most of their light in the blue and ultraviolet regions of the
spectrum. Stars cooler than the Sun (below 5,000 degrees C) put out most of their light in the red and infrared regions of the
spectrum. Solid objects heated to 1,000 degrees C appear red but are putting out far more (invisible) infrared light than red
light.
How are wavelength and temperature related?
All objects emit electromagnetic radiation, and the amount of radiation emitted at each wavelength depends on the
temperature of the object. Hot objects emit more of their light at short wavelengths, and cold objects emit more of their light
at long wavelengths. The temperature of an object is related to the wavelength at which the object gives out the most light.
D. Application
 ORAL RECITATION (SOCRATIC METHOD)
III. EVALUATION/ASSESSMENT
IV. Direction: Complete each statement by supplying the correct term. You may choose the answer from the box
below.
Refraction bends towards the normal
Mirage incident ray
bends away from the normal medium
1. The bending of light when it passes obliquely from one medium to another is known as ________.
(refraction)
2. Refraction is the bending of light from one ________ to another. (medium)
3. When light passes from a less dense to a denser medium, it _____.
(bends towards the normal)
4. When a light ray passes from water to air (denser to a less dense medium), its path __________. (bends
away from the normal)
5. The phenomenon that motorists observe on hot days when the road seems to be covered with water.
(mirage)
Fill in the missing term:
1. The splitting of white light into several colors on passing through a glass prism is due to____.
2. When does a rainbow occur in nature? _____
3. Rainbow formation is due to_____.
4. Which color is bent the most? ____
5. Which color is bent the least? ___
Answers:
1. Dispersion
2. After the rainstorm, when the sun comes out

3. the properties of light namely reflection, refraction ,total internal reflection and dispersion
4. violet
5. red
Directions: Choose the letter of the correct answer.
1. Which of the following lights has the highest frequency?
a. red b. blue
c. green d. violet
2. What do different wavelengths of light represent?
speed b. amplitude
colors d. frequency
3. A rainbow usually appears in the sky after a rain. Which of the following statements best explain this
observation?
a. Raindrops acts as prism separating sunlight into colors.
b. The white clouds actually prism composed of different colors.
c. The colors of the rainbow comes from the raindrops in the
atmosphere
d. When sunlight is reflected by the ground towards the clouds, it
separate into different colors.
4. Which of the following has the longest wavelength?
a. red b. violet
c. orange d. green
5. The process of separating white light into bands of colors using a prism is known as _________.
a. refraction
b. dispersion
c. reflection
d. diffraction
POST ASSESSMENT:
The assessment for the day will be based on the outcome/output of the activity: the color wheel. It will be graded
based of the rubric below.
V. ASSIGNMENT/AGREEMENT/ENRICHMENT
Research about REFRACTION OF LIGHT RAYS, DISPERSION, COLORS IN RELATION TO
ENERGY,AND REFRACTIVE INDEX OF THE COLOR OF LIGHT
VI. REMARKS:
Mastery level:
Needs remediation:
Student was mindful of classroom rules/procedure
Student follows direction
Student labeled the output correctly(colors and
fractional parts
Colors placed in appropriate place on color wheel
The finish product was neat.
TOTAL POINTS:

Lights lesson plan

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Lights lesson plan