Government Property

NOT FOR SALE Senior High School

Physical Science
Quarter 2
Module 7: Light as Wave and a Particle

What This Module is About

We live in a colorful world. The green leaves of trees, the blue lakes and oceans, the white
clouds, the red-orange horizon, the colorful rainbow, the multicolored landscape to name a few. We
see these wonderful creations because of the presence. of light. Would it be wonderful to know the
science behind all these?
In this module, you will be introduced to the dual nature of light, its properties and behavior,
and the various optical phenomena created by light. It includes light being a particle and a wave or
both. Some properties of light can be explained by considering light as a wave (interference of light,
diffraction and scattering) while other properties can be explained by considering light as a particle
(photoelectric effect) and still others can be explain considering light as both wave and particle
(reflection, refraction and dispersion). It also includes the wave-like characteristics of electron and
how Hertz produced radio pulses applying the evidence- based knowledge of his predecessors on
light and electron.
Quite interesting! You may now start exploring this module.
The following are the lessons contained in this module:
1. The Wave-Particle Duality of Light
2. The Photon concept and How we see colors
3. Wave-Like Property of Electron
4. The Properties of Light
5. Various Light Phenomena
6. How Hertz Radio Pulses

What I Need to Know

At the end of this module, you should be able to:
1. Describe how the propagation of light, reflection, and refraction are explained by the wave
model and the particle model of light (S11/12PS-IVf-59);
2. Explain how the photon concept and the fact that energy of a photon is directly proportional
to its frequency can be used to explain why red light is used in photographic dark rooms, why
we get easily sunburned in ultraviolet light but not in visible light, and how we see colors
(S11/12PS-IVf-61);
3. Cite experiment evidence showing that electrons can behave like waves (S11/12PS-IVf-6);
4. Differentiate dispersion, scattering, interference, and diffraction (S11/12PS-IVf-65)
5. Explain various light phenomena such as:
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 A. Your reflection on the concave and convex sides of a spoon looks different
B. Mirages
C. Light from a red laser passes more easily through red cellophane than green cellophane
D. Clothing of certain colors appear different in artificial light and in sunlight
E. Haloes, sundogs, primary rainbows, secondary rainbows, and supernumerary bows
F. Why clouds are usually white and rainclouds dark
G. Why the sky is blue and sunsets are red (S11/12PS-IVf-66)

Lesson 1 The Nature of Light

What I Need to Know

What is light? Is it matter or is it energy? Do you think it is a particle or a wave?
For hundreds of years, scientists disagreed on the nature of light. In this lesson you will be able to
describe how the propagation of light, reflection, and refraction are explained by the wave model
and the particle model of light.

What’s New
Activity 3.2.1. Observing a Ball’s Path at Different Speeds (1 point each)
Find a space in your yard where you can safely play a ball. Face a wall, boundary or fence at about
two meters away from it. Throw the ball slowly. How will you describe the trajectory path of the
ball? Record your observation in the table below. Throw the ball again but his time do it very fast.
Complete the table.
Ball’s Speed Versus Path
Speed Observation of Ball’s Path
Slow
Fast

What Is It

At slow speeds, a curvature of a thrown ball was easily observed because of the effect of gravity
but at high speeds the ball is inclined to follow a straight line.
According to Sir Isaac Newton, light travels in straight lines, thus
its particles must move at very high speeds.

Light can travel straight through empty space (vacuum) until

it hits something else. Once it has hit another surface or particle,
it is either absorbed, reflected (bounces off), refracted (direction
and speed changes), scattered (bounce-off in all directions) or
transmitted (passes straight through) as seen in Figure 1. But is
light a wave or a particle? Figure 1: Propagation of :Light

The Corpuscular (particle) Theory – Newton’s Theory

According to the theory, Newton thought that light is made up of particles that travel
through space on a straight line.

• Reflection is the bouncing of light as it hits a surface. Newton demonstrated that particles
collide with the surface and bounce back (see figure a).
• Refraction is the bending of light. It is an attraction between the molecules of the medium
and the particles of light which contribute to the change of speed as the particles of the light
travels inside the medium (see figure c)
• Diffraction is the bending of light as it passes around the edge of an object. Newton felt that
light does not travel around corners. He explained that any observed effect of this is caused
by the interaction of particles when they run into each other at the edges of the objects.
• Dispersion is the separation of light into colors. Newton explained that particles of different
mass would be affected differently when refracted.

Figure 2. The reflection of ligjht (a) particles and (b) waves; refraction of light on (a) particles) and (b) waves

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Wave Theory of Light

Christian Huygens, a Dutch physicist, argued that if light were made of particles, when light
beams crossed, the particles would collide and cancel each other. He proposed that light was a
wave similar to that of water waves.

• Huygens’ Principle – each point on a wave, behaves as a point source for waves in the direction
of wave motion. Huygens’ wave model of light explains reflection, refraction, and diffraction of
light
• Reflection happens when light bounces off an object. Upon hitting a smooth surface as
illustrated in figure b, light would be reflected. The waves would bounce back, producing a
reversed image of the wave.
• Refraction – is the bending of wave when it enters a medium where its speed changes. In figure
d, the wavefront approaches the two media with different densities. Since the incident wave is
travelling as an angle, a small portion of the wavefront starts to slow down upon impact to the
boundary while the rest are maintaining their speeds. This condition makes the wavefront bend
while entering the second medium with higher density.
• Diffraction is the slight bending of light as it passes around the edge of an object which
depends on the relative size of the wavelength of light to the size of the opening. Light is a
particle, a wave or both depending on the phenomenon.

Behavior of Light
Phenomenon Can be explained in terms of waves Can be explained in terms of particles
Reflection ✓ ✓
Refraction ✓ ✓
Interference* ✓
Diffraction* ✓
Polarization* ✓
Photoelectric ✓
effect*
*Shall be discussed in details in the succeeding lessons

What’s More
Activity 3.2.2 Exploring How Light Travels (10 points)

Go back to your front yard or backyard. Pick 3 best selfie spots, but before posing for your camera,
observe your shadow as you go through those spots.
1. Where did you see the shadows?
______________________________________________________________
2. Did the shadows change? __________________________________________________________________
3. Under what circumstances? ________________________________________________________________
4. Take selfies facing different directions. In the context of light, under what circumstances did
you have a nice selfie photo? Justify your answer.
_______________________________________________.
5. Upload your best and worst capture in your Physical Science group chat on Messenger or
Google Classroom.

What I Have Learned

Activity 3.2.3 Sharing My Insights (Criteria: Critical Thinking-5, Communication-5)

Based on the lesson on Corpuscles Theory and Wave Theory of Light, I have realized that
_________________________________________________________________________________________________

What I Can Do
Activity 3.2.4 Reflecting Me (1 point each).

Complete the chart to describe how reflection and refraction are explained by the wave
theory and the particle theory of light

Phenomena Description
By Wave Theory of Light By Particle Theory of Light
Reflection
Reftaction

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 Lesson 2 Energy of Light
What’s In
Light may behave as a particle, a wave or both depending which light phenomenon. To
scientists, colors of things are not substances of the things themselves but the frequencies of light
emitted or reflected by things.

What I Need to Know

In this lesson, you will be able to explain how the photon concept and the fact that the energy of a
photon is directly proportional to its frequency can be used to explain why in photographic dark
rooms red light is used, why in ultraviolet light but not in visible light we get easily sunburned, and
how we see colors.
.
What’s New
Activity 7.2.1 Arranging Rainbow Colors (1 point each).
Open your Facebook app. Type visible light spectrum on the search bar. Go through the resources
and observe the frequencies and energies of the different colors. Arrange the colors according to
increasing frequency and increasing energy in the table below.

Red Orange Yellow Green Blue Indigo Violet

Parameter 1 2 3 4 5 6 7
Frequency
Energy

What happens to the energy of light as the frequency increases? ______________________________

What Is It

Newton thought that light was made of particles (corpuscles) that emanated from the light
source. Light can be described as a quanta or packet of energy that behaves as if they were
particles. Light quanta are called photons. The photoelectric effect introduced evidence that light
showed particle properties. Photons are emitted when electrons of an atom are excited.

When light is shown on an atom, its electrons absorb photon which causes them to gain
energy and jump to a higher level. Since an electron can only exist at certain energy levels, it can
only emit photons of certain frequencies. The emitted light can be perceived as a series of colored
lines called a line or atomic spectra. Each element produces a unique set of spectral line.

The electromagnetic spectrum depict all of the types of light, including those that we cannot
see in our own eyes. In fact, most of the light in the universe is invisible to humans.

The light we can see, made up of the individual colors of the rainbow, represents only a very
small portion of the electromagnetic spectrum. It is called visible light. Other types of
light include radio waves, microwaves, infrared radiation, ultraviolet rays, X-rays and gamma rays
— all of which are imperceptible to human eyes.

Figure 3. The Electromagnetic Spectrum EM

The relationship between energy and frequency is given by the equation E = hf, here h is 6.63
x10-24 joules-second called as Planck's constant. A direct relationship exists; electromagnetic
radiation is more energetic with a higher frequency.

Why do we get easily sunburned in ultraviolet light but not in visible light? The sun is a
source of the full spectrum of the ultraviolet radiation which is responsible for causing us sunburn.
This UV light has higher frequency than visible light, therefore it has higher energy.

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 Why is red light used in photographic darkrooms? Darkrooms used red lighting to allow
careful control light to pass through, so that photographic paper which is light sensitive would not
become overexposed that will result to ruining the pictures during the developing process. Red light
in the visible region of the spectrum has the lowest frequency and lowest energy and therefore it
does not affect the photo developing process.

How do we see colors? Visible light is a small part within the spectrum that human eyes are
sensitive to and can detect. It is of different frequencies and each frequency is a particular color.
Objects appear in different colors because they absorb some colors and reflect or transmit the
others. White objects appear white because they reflect all colors. Black objects absorb all of them
so no light is reflected.
Life and Electromagnetic Waves

Type Applications Life sciences aspect Issues

Requires controls for
Communications
Radio MRI band use
remote controls
Communications,
Microwaves Deep heating Cell phone use
ovens, radar
Thermal imaging, Absorbed by
Infrared Greenhouse effect
heating atmosphere
Photosynthesis,
Visible light All pervasive
Human vision
Sterilization, Cancer Ozone depletion,
Ultraviolet Vitamin D production
control Cancer causing
Medical diagnosis,
X-rays Medical Security Cancer causing
Cancer therapy
Nuclear medicine, Medical diagnosis, Cancer causing,
Gamma rays
Security Cancer therapy Radiation damage

What’s More
Activity 7.2.2 Spotting Similarities and Differences (Criteria: Critical Thinking-5,
Communication-5, Creativity-5)

Compare and contrast any two of radio waves, microwave, infrared, visible light, ultraviolet,
x-ray and gamma ray in terms of properties. Present your output creatively.

What I Have Learned

Activity 7.2.3 Writing it Right (Criteria: Critical Thinking-5, Communication-5)

Based on the lesson on frequency and energy of light, I have realized that
________________________________________________________________________________________________

What I Can Do
Activity 7.2.4 Matching Perfectly (1point each).
Directions: Match the expressions in column A with those in column B by placing the letter that
corresponds to the best answer on the space provided.

A B
______1. Using red light in photographic darkroom a. higher frequency. higher energy
______ 2. Getting sunburned in ultraviolet light b. higher frequency. lower energy
______ 3. Seeing white t-shirt as blue c. lower frequency, higher energy
d. lower frequency, lower energy

Lesson 3 Wave Property of an Electron

What I need to Know
In this lesson, you should be able to some cite experimental evidence showing that electron
can behave like a wave.

What’s In
In the preceding lesson, you learned that light can behave as particle and as a wave. The
idea of photoelectric effects, which show the particle property of light fascinated the French
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physicist, Louis de Broglie. If light being a wave can show a particle-like property, then electron
and other particles may also have a wave-like properties such as wavelength and frequency.

What’s New
Activity 7.3.1 Let’s Match History!

1. Match the year, the scientist and their contribution to the development of the wave-like
property of electron.
2. Write your answer in the column for Coded Answer.

A (Year) Coded Scientists Contribution

Answer
1. 1900 1. ___, __ A. Albert Einstein G. proposed that electron could
have wave-like properies
2. 1905 2. ___, ___ B. Clinton Davisson and H. Photoelectric effect
Lester Germer
3. 1922 3. ___, ____ C. Arthur Holy Compton I discovery of Planck’s radiation law
4. 1924 4. ___, ____ D. Max Planck J. announced the complementary
relation between the wave and
particle aspect of electron
5. 1927 5. ____, ___ E. Louis de Broglie K. Compton effect
6. 1928 6. ___, ___ F. Neils Bohr L. experimentally established the
wave-nature of electron

What Is It

In 1900, Max Planck was able to formulate and discover the so-called Plank’s constant which he
included in his discovery of Plank’s radiation Law. In 1905 German physicist Albert Einstein first
showed that light, being considered as a form of EM wave, can be thought as a particle and
localized in packets of discrete energy. This was shown in his photoelectric effect experiment. The
observations of the Compton effect in 1922 by American physicist Arthur Holly Compton could be
explained only if light had a wave-particle duality. Fascinated with the idea that light as a wave can
have a particle like property, in 1924, French physicist Louis de Broglie proposed
that electrons and other discrete bits of matter, which until then had been conceived only as
material particles, must also have wave properties such as wavelength and frequency. Later in 1927
the wave nature of electrons was experimentally established by American physicists Clinton
Davisson and Lester Germer on their Davisson-Germer experiment. An understanding of the
complementary relation between the wave aspects and the particle aspects of the same
phenomenon was announced by
Danish physicist Niels Bohr in
1928.

What’s More
Activity 7. 3.2 Where Can I
Find You?

1. Encircle as much words that

relate to the wave-like
property of electron on the
puzzle mat.

2. It can be horizontal, vertical,

or diagonal.

3. You may copy the puzzle in

your journal notebook and
answer it.

4. Goodluck and enjoy the

puzzle.

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What Is It
Electron being considered as a wave created questions that gain the interest of another fellow
scientist. Among the question that lingered on the minds of other scientists was that “if electron
traveled as a wave, then where could be the precise position of the electron within the wave?”
The answer to this question was given by German physicist Werner Heisenberg in 1927, in his
famous Heisenberg Uncertainty Principle. He articulated that both the momentum and position of
the electron cannot be measured exactly at the same time.
Another scientist in the name of Erwin Shrodinger derived set of equations also called wave
functions for electrons as a result of de Broglie’s hypothesis and Heisenberg’s uncertainty principle.
He formulated the equations that would specify that the electrons confined in their orbits would set
up standing waves and the probability of finding the electrons in the orbitals could be described as
the electron density clouds. The greatest probability of finding an electron in an orbital is in the
densest area, likewise, the lowest probability of finding an electron in in the orbital of least dense.

What I Have Learned

Activity 7.3.4 Let me Test Myself!

What are some experimental evidence showing that electron has a wavelike property. Write
your answer in your journal notebook.

What I Can Do
Activity No. 7.3.5. Challenge the Scientist in Me!

I. Choose any 1 of the activity.

A. Search on Davisson-Germer Experiment that confirms De Broglie’s hypothesis. Make a
synthesis of their experiment. Write it in your journal notebook.

B. Watch the video on You tube “De Broglie wavelength/Khan Academy @

https://www.khanacademy.org/science/physics/quantum-physics/toms-and-
electrons/v/de-broglie-wavelength

Lesson 4 Properties of Light

What’s In

As you may recall, the wave-particle nature of light can explain why light is reflected or it may
bounce back as it hit an opaque surface and it shall be refracted or bend as it passes through a
transparent material. In this lesson you shall encounter more properties of light that may uncover
the formation of rainbows, the rainbow-colored soap bubbles that you played with your younger
siblings, the beautiful horizon that you experience in the late afternoon and white fluffy clouds
below the blue sky during the midday.

What’s New
Do you ever wonder how multicolored rainbows are form? Perform the next activity diligently to
know how.

Activity 7.4.1 Am I Dispersed? (Adopted from project EASE-physics Module 3)

Materials: a prism or a clear bottle half-filled

with water
Flashlight or sunlight
Procedure: Hold a prism or a bottle half-filled with
water against sunlight or any light source like a
flashlight. Observe.

Guide questions:
1. What do you see?
2. Enumerate the colors you observe.

What Is It
Dispersion
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 As light enters into a prism, or an object that may act as a prism, it separates into different
band of colors. This separation of white light into different colors as it passes through a prism is
called dispersion. The separated band of colors, red, orange, yellow, green, blue, indigo and violet,
ranges from 400 nanometer to 700 nano meter wavelength. Dispersion occurs due to the slight
difference in the refractive index of each color.
A rainbow is formed after a rainshower when droplets of falling water acts as a prism that
separates the rays of the sun hitting the water droplets into band of different colors.
Figure __. A rainbow captured after a
What’s More rainshower in Baungon, Bukidnon. Photo
credits to Ms. Marivic Labita.
Activity 7.4.2 What A Colorful Day!

Now, get your pen and journal notebook and go outside for a while and look up the sky above
you. Note down the things and colors you have noticed. Repeat your observation at anytime of the
day and in the late afternoon. You may do this observation activity for a series of 2-3 days when
the weather Is fine. Keep your journal notebook handy. Good luck!

What Is It
Did you observe the beautiful, fluffy white clouds like
cottons arrange under a faint blue sky during the middle of the
day when the sun is shining brightly and the beautiful red-
orange horizon in the late afternoon when the sun is almost
setting down?

Scattering of light is responsible for this blue-colored sky

and beautiful horizon. Tiny dust particles, and atoms of oxygen
and nitrogen in the atmosphere which are far apart from each
other acts as scatterers. They scatter sunlight in all directions.
Of the band of colors of light, violet has the shortest wavelength
of 400 nanometer. It is scattered the most, followed by indigo,
A view from San Franz, El Salvador City
blue, green, yellow, orange and red which is scattered the least. Photo credits to Mr. Zigger Villahermosa,
But our eyes is not sensitive to indigo and violet, and blue is SH of San Franz ES, El Salvador City
most predominant to our sight, so we see the blue sky. Division
In the late afternoon where the sun is in the horizon, the
loner wavelength red light reaches our eyes more than the blue
light which are scattered the most. Red being scattered the least
is transmitted and passed through more of the atmosphere than
any other color. Thus, it is the red color together with some
orange that reaches our eyes in the late afternoon and we see
the beautiful red-orange sunset.
Clouds are made of water droplets of varying sizes.
Smaller droplets scatter blue, green, and yellow and even red
color. A combination of these color results in white clouds.
Rain clouds appear dark because the water droplets
become bigger and denser and it can absorb lighter than scatter
it. It almost all colors are absorbed, the resulting color is dark or even black.
So, the next time you look up the sky and view the horizon, you know the science behind its beauty.

What’s More
Activity 7.4.3. Let me Interfere!

Materials: Liquid soap, water, basin

Procedure: Put some water in a basin and pour a good amount of liquid soap. Stir and make soap
suds. Blow on soap suds. Observe.

Guide Questions:
What can you observe in the soap bubbles. Write your observation on your journal notebook.

What Is It
Interference of light

The beautiful spectrum of colors reflected on the soap bubbles are produced by the
interference of light. It occurs when 2 waves meet while travelling on the same medium. It may be
constructive interference producing bright fringes or destructive interference producing dark bands.
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In the case of soap bubbles, the incident ray of white light constructively interfere in the different
regions of the bubbles producing the rainbow-colored appearance. Interference of light clearly
demonstrates the wave nature of light.

What’s More
Activity 7.4.4 Let me see you through!
1. Look at the light through the slit between your fingers. What do you observe? Do you see
vertical white and dark bands? What causes this bands?
2. Repeat step 1 but make the slit narrower. Compare your observations with the previous one.
3. Write your observation in your Journal notebook.
What Is It
As you look the light through the slit between your fingers, you will observe the vertical white and
dark bands which is due to the bending of light as it passes through an opening or an obstacle.
This is described as diffraction of light.

The narrower the slit, the more pronounced the pattern become .

What I Have Learned

Activity 7.4.5 You Complete Me!
I. Complete the table below: Write your answer in your journal notebook.

Properties of Light Description Applicable light phenomena

1. 2. Rainbow
Scattering of light 3. 4.
Diffraction 5. 6.
7. 8. Rainbow-colored appearance in soap bubbles

What I Can Do
Activity 7.4.6 Let Me be a Collector!
Take and collect pictures applying at least two of the four properties of light mentioned in
this lesson. Post it on your journal notebook and briefly describe the science behind the pictures.
Submit your journal notebook to your teacher for the rating.

Hoorah and happy learning!

Lesson 5 Various Light Phenomena

What’s In
In lesson 4, you have learned that rainbows are formed due to the dispersion of light in water
droplets that acts as a prism. You have also learned that the blue sky, the reddish sunset and the
white and dark clouds are products of the scattering of light in the atmosphere; the rainbow-colored
soap bubbles are due to the interference of light and the bright fringes and dark bands in shadows
are result of the diffraction of light.
In the previous lesson, you knew that light reflects or bounce back as it hits an opaque
object such as mirror and transmitted through transparent objects such as glass and lenses. Light
refracts or bend as it enters from one medium to another with different optical density. You also
knew that the colors we see on the object is the color of light that is reflected by the object to our
eyes. The green color of the leaves is the due to the green light that is reflected by the leaves to our
eyes, and all the other color of light is absorbed and only the green is reflected.
These behaviors of light produce spectacular light phenomena that we often see in our daily
life and sometimes we may not notice it.

What I Need to Know

In this lesson, you are expected to explain various light phenomena such as your reflection
on the concave and convex side of a spoon, mirage, haloes, sundogs, primary and secondary
rainbows and supernumerary bows, You are also expected to explain why a red laser light passes
through easily on a red cellophane than on a green one and why colors of clothing appears different
in artificial light as compared to natural sunlight.

What’s New
Activity No. 7. 5. 1 A. My Spoony Image

Page 9 of 12
 1. In a well-lighted room, Hold a shiny spoon with the back side facing at you. Look at you
image and describe your observation.
2. Now, turn the spoon such that the front side faces you. Observe and describe your image.
3. Write your observations in your journal notebook.

Activity No. 7. 5. 1 B. May I Pass Through

Point a red laser light at 90 degree or perpendicular to a red colored cellophane. Observe the
transmitted light on a screen (may be a white bond paper or white wall). Note your observation in
your journal notebook.
1. This time, use a green cellophane, instead of red and do the same as procedure no. 1. What
do you observe? Again, write your observation in your journal notebook.

What Is It
For activity 7.5.1A, the back side of the spoon represents a convex mirror while the front side of the
spoon represents the concave mirror. Recalling the images formed in a convex and concave mirror.
In a convex mirror, reflected light rays diverge as if it originates from the imaginary focus of the
mirror, thus producing a small, upright and reverse image just as what you observe. For concave
mirror, reflected light rays bend towards the focus of the mirror, thus producing an upside down or
inverted image.

For Activity 7.5.1B, colored cellophane acts as filters for allowing certain colors to pass through
while absorbing the other colors. In the case of the activity, red laser light passes through more
easily in red cellophane than in green one because much of the red light is absorbed in the green
cellophane.

Light is transmitted in transparent materials without being scattered at an angle of 90 degree,

otherwise, light is refracted, but not 100 % of the incident light is transmitted, some are absorbed
and others are reflected.

When light hits an object, some of its frequencies are absorbed and few are reflected. Such in a case
of green leaves, only green frequency is reflected while the other frequencies are absorbed by the
object. The green light is reflected to our eyes, and we see it green. When all frequencies of light is
reflected, we see white object, such as the white clouds, but when all frequencies of light are
absorbed, we see the object black.

Colored objects have pigments capable of reflecting specific colors of light. A blue colored dress
reflects the blue frequency and absorbs the other. But comparing the results of reflection from a
natural sunlight and an artificial light source such as from a LED light, the color intensities is
different. The blue dress would appear pale blue in an artificial light because it contains less
amount of blue light as compared to the natural sunlight.

What’s More
Activity 7.5.2. Picture Analysis
Analyze the photographs of different optical phenomena and answer the guide questions below on
your journal notebook.

A. B. C.

D. E.

Guide Questions:
1. On a very sunny day, have you observe the apparent pool of water on a straight highway?
What do you call this phenomena and what causes this? Which photo is this?
2. Which photo shows a halo? What causes the formation of haloes?
Page 10 of 12
 3. Which photo depicts sundogs? What property of light causes sundogs?
4. Rainbows are spectacular view in the sky. What is the difference between a primary rainbow
and secondary rainbow?
5. Which among the pictures is a supernumerary bow?

What I Have Learned

Activity 7.5.3 Let’s Test your Understanding
Answer the questions briefly. Write your answers on your journal notebook.

1. Compare and contrast the images form in front side and the in the back side of a shiny spoon.
What does the front side of the spoon represent? The back side?
2. Why does red light passes through easily in red cellophane? What happens to the green light
as it passes through the red cellophane?
3. The color of the dress when artificial light is shone upon it is different compared to the color
of the dress when natural sunlight is shone upon it. Why?
4. What behavior of light is responsible for the formation of mirage?
5. What are the similarities and differences of a halo and a sundog?
6. How is a primary and secondary rainbow different?
7. What is a supernumerary bow? How is it form?

What I Can Do
Activity 7.5.4 Let’s Illustrate!
Now that you have studied various light phenomena, make a sketch or illustrate the following in
your journal notebook. Color your illustrations properly.
1. A primary and secondary rainbow from an observer’s eye
2. A supernumerary bow located at the inner of a primary bow.
3. An image of a red rose reflected on the front side of the spoon.
4. An image of a native fruit as reflected on the back side of the spoon.
5. The color difference of an orange dress when an artificial light shine on it side by side with
same dress illuminated by the natural sunlight.

Lesson 6 HERTZ
What’s In
In the previous topic, you have learned about light phenomena that are any observable
events that result from the interaction of light and matter. Various light phenomena are often due
to the interaction of light from the sun or moon with the atmosphere, clouds, water, dust, and other
particulates. Light phenomena includes rainbows, haloes, white clouds and blue sky.

What I Need to Know

(http://www.brainkart.com/article/Production-and-properties-of-electromagnetic-waves---Hertz-experiment_38544/)

What Is It
“I do not think that the wireless waves I have discovered will have any practical
application.”
HEINRICH HERTZ
1890

https://www.famousscientists.orghow-hertz-discovered-radio-waves

Heinrich Rudolf Hertz (1857–1894) was a German physicist who became the first person to
transmit and receive controlled radio waves. He was the first conclusively proved the existence of
electromagnetic waves theorized by James Clerk Maxwell's electromagnetic theory of light.
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It seems a little odd looking back that he had no practical purpose in mind for the radio waves he
discovered considering how indispensable his wireless transmissions quickly became. His
research focused only on discovering if James Clerk Maxwell’s 1864 theory of electromagnetism
was correct. Hertz was able to measure their wavelength and velocity but was not only able to
detect the waves. The scientific unit of frequency was cycles per second or named "hertz" in his
honour.
Hertz proved the theory that ruled out all other known
wireless phenomena by engineering instruments to
transmit and receive radio pulses using experimental
procedures. He designed a brilliant set of experiments to
test Maxwell's hypothesis. His apparatus consists of
polished brass knobs, each connected to an induction
coil and separated by a tiny gap over which sparks
could leap.

Hertz attached a secondary spark-gap to the existing

spark-gap. He used the induction coil to generate high
voltage ac electricity and producing a series of sparks at
regular intervals at the main spark-gap.

Hertz noticed that when sparks flew across the main

gap, that is between points A and B in the image; Hertz
called these side-sparks. He found that the behavior of
the side-sparks highly provoking. He diverse the
position of connection point C on the side-circuit. The Hertz spark testing
only way he could stop side-sparks produced was to circuit
arrange the connection so the length of wire AC was the https://www.famousscie
same as BC, Hertz suggested since the given that the ntists.orghow-hertz-
electricity was ac, the voltage waves were separately racing through the wire along paths AC and
discovered-radio-waves
BC. If the distances of AC and BC were the same, then the same voltage must arrive at points A and
B at the same time. Sparks could not be generated if the electrical waves in AC and BC were said to
be in phase with one another. If there was a large voltage difference between points A and B, sparks
could only be generated

What I Have Learned

Activity 7.6.3. Test your Memory
Answer the following questions briefly: Write your answers in your journal notebook.

1. What is the unit of frequency?

2. Why large voltage will be used to produce sparks based on Hertz experiment?
3. In Hertz testing circuit, why distance between CA and CB were the same?
4. How Hertz experiment produced sparks?
5. Was Hertz successfully proved the James Clerk Maxwell's electromagnetic theory of light?

What I Can Do
Activity 7.6.4. Research Time
Do some Research Study. Record your output in your journal notebook.

1. Differences between AM and FM.

2. Why NTC order to stop the ABS-CBN in using their frequency?

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