Physical Science Module 7 -Dual Property of Light-as wave and particle PDF

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NOTPHYSICAL SCIENCEQuarter 2 - Module 7LIGHT AS WAVE AND A PARTICLEDepartment of Education ● Republic of the PhilippinesGovernment PropertyNOT FOR SALE Senior High####### SchoolPhysical Science - Grade 12 Alternative Delivery ModeQuarter 2 - Module 7: Light as a Wave and a ParticleFirst Edition, 202...

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NOT FOR SALE

Senior High School

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PHYSICAL SCIENCE Quarter 2 - Module 7 LIGHT AS WAVE AND A PARTICLE

Department of Education ● Republic of the Philippines

Physical Science - Grade 12 Alternative Delivery Mode Quarter 2 - Module 7: Light as a Wave and a Particle First Edition, 2020 Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalty. Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names, trademarks, etc.) included in this book are owned by their respective copyright holders. Every effort has been exerted to locate and seek permission to use these materials from their respective copyright owners. The publisher and authors do not represent nor claim ownership over them. Published by the Department of Education – Division of Cagayan de Oro Schools Division Superintendent: Dr. Cherry Mae L. Limbaco, CESO V Development Team of the Module Author/s: Naome S. Lagos, Jennifer Jude G. Ragandang, Doris Pabalate Reviewer: Jean S. Macasero Illustrator and Layout Artist: Management Team Chairperson: Dr. Arturo B. Bayocot, CESO III Regional Director Co-Chairpersons:

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Senior High School

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

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Department of Education ● Republic of the Philippines

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Table of Contents What This Module is About........................................................................................................................i What I Need to Know...................................................................................................................................ii How to Learn from this Module................................................................................................................ii Icons of this Module....................................................................................................................................iii What I Know.................................................................................................................................................iii

Lesson 1: The Nature of Light.....................................................................................................................1 What I Need to Know...........................................................................................1 What’s New: Observing a Ball’s Path at Different Speed...............................1 What Is It the Corpuscular and Wave Theory of Light....................................1 What’s More: Exploring How Light Travels......................................................2 What I Have Learned: Sharing my Insights......................................................2 What I Can Do: Reflecting Me............................................................................2

Lesson 2: Energy of Light What’s In............................................................................................................... 3 What I Need to Know...........................................................................................3 What’s New: Arranging Rainbow Colors ........................................................3 What Is It: .............................................................................................................. 3 What’s More: Spotting Similarities and Differences.........................................3 What I Have Learned: Writing it Right

…………………………………..… 3

What I Can Do: Matching Perfectly …..............................................................4

Lesson 3: Wave-like Properties of Electron.......................................................................4 What I Need to Know..................................................................................4 What’s In.....................................................................................................4 What’s New: Let’s Match History................................................................5 What Is It:.................................................................................................... 5 What’s More: ..............................................................................................5 What I Have Learned: Let me Test Myself…………………………….…..… 6 What I Can Do: Challenge the Scientist in Me…........................................6

Lesson 4: Properties of Light......................................................................................................................7 What’s In.....................................................................................................7 What’s New: Am I Dispersed...................................................................7 What Is It: Dispersion................................................................................8 What’s More: What a Colorful Day............................................................8 What Is It: Scattering of Light....................................................................8 What’s More: Let Me Interfere...................................................................9 What Is It: Interference of Light................................................................9 What’s More: Let Me See You Through.....................................................9 What Is It: Diffraction.................................................................................9 What I Have Learned: You Complete Me………………………………….…10 What I Can Do: Let Me be a Collector ….................................................10

Lesson 5: Various Light Phenomena..................................................................................................11 What’s In.....................................................................................................11 What I Need to Know..................................................................................11 What’s New: My Spoony Image/May I Pass Through..............................11 What Is It:................................................................................................. 12 What’s More: Picture Analysis...................................................................13 What I Have Learned: Let’s Test Your Understandng………………………14 What I Can Do: Let’s Illustrate…..............................................................14

Lesson 6: HERTZ........................................................................................................................................................15 What’s In.....................................................................................................15 What I Need to Know..................................................................................15 What’s New: Arrange the Colo According to Frequency...........................16 What Is It: ................................................................................................ 16 What’s More: Hertz Experiment................................................................17 What I Have Learned: Test Your Memory……………………………….…17 What I Can Do: Research Time …............................................................18

Summary Assessment: (Post-Test) ……………………………………………………………………...19 Key to Answers................................................................................................................ 21 References...................................................................................................................... 23

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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 explain by considering light as a wave (interference of light, diffraction and scattering) while other properties can be explain 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. 2. 3. 4. 5. 6.

The Wave-Particle Duality of Light The Photon concept and How we see colors Wave-Like Property of Electron The Properties of Light Various Light Phenomena 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 (S11/12PSIVf-6); 4. Differentiate dispersion, scattering, interference, and diffraction (S11/12PS-IVf-65) 5. Explain various light phenomena such as: 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) 6. Describe how Hertz produced radio pulses (S11/12PS-IVf-68)

How to Learn from this Module To achieve the objectives cited above, you are to do the following: • • • • • •

Get your pen and journal ready. Take your time reading the lessons carefully note taking important information and key words. Follow the directions and/or instructions in the activities and exercises diligently. Perform the activities to heart. Write your observations in your journal. Answer all the given tests and exercises as honestly as possible. If you have any questions for clarification, feel free to consult your teacher.

Icons of this Module What I Need to

This part contains learning objectives that

Know

are set for you to learn as you go along the module.

What I know

This is an assessment as to your level of knowledge to the subject matter at hand, meant specifically to gauge prior related

What’s In

What’s New

knowledge This part connects previous lesson with that of the current one.

An introduction of the new lesson through various activities, before it will be presented to you

What is It

These are discussions of the activities as a way to deepen your discovery and understanding of the concept.

What’s More

These are follow-up activities that are intended for you to practice further in order to master the competencies.

What I Have Learned

Activities designed to process what you have learned from the lesson

What I can do

These are tasks that are designed to showcase your skills and knowledge gained, and applied into real-life concerns and situations.

What I Know

Multiple Choice. Select the letter of the best answer from among the given choices. 1. Which of the following phenomena describes no difference between the wave theory and particle theory of light? A. diffraction B. interference C. reflection D. refraction 2. Which factor remains constant when light travels in a different medium? A. Color B. Frequency C Speed D. Wavelength 3. Why does a blue t-shirt appear blue? A. Blue is absorbed by the t-shirt B. Blue is emitted by the t-shirt C. Blue is reflected by the t-shirt D. Blue is refracted by the t-shirt . 4. E=hf is an equation that describes the relationship between energy (E) and frequency of light (f). What will happen to the energy of light as the frequency goes higher? It A. goes higher B. goes lower C. remains the same D. undetermined 5. Under which type of light do we easily get sunburned? A. infrared B. microwave light C. ultraviolet light D. white light 6. He formulated the hypothesis that electron being a particle has wave-like characteristics. A. Albert Einstein C. Louis de Broglie B. Max Plank D. Neils Bohr C. 7. Which property of light is responsible for white clouds, blue sky and red sunset? A. Dispersion C. Interference B. Scattering D. Diffraction 8. What natural occurrence is produced by the refraction of light as it travels between hot and cold air? A. mirage C. virtual image B. myriad D. real image 9. Which of the following situations exemplifies the dispersion property of light? A. The image of the flower in a mirror B. The sparkling glow of the diamond ring C. The swaying movement of coin under water D. The rainbow in the sky after the rain shower 10. Explain when can diffraction of light occur? A. When photons oscillate in certain directions are absorbed, while others that oscillate in line with the filter pass through. B. when light strikes the boundary between substances at an angle greater than the critical angle. C. when waves spread and bend as they pass through small openings or around barriers. D. when two or more waves overlap or intersect. 11. What effect does interference of light waves have on soap bubbles? A. They become larger B. They become heavier C. They produced different colors at the surface. D. They produced images of objects like a mirror.

12. After a rainstorm, a rainbow may appear in the sky. Which statement explains this observation? A. The colors of the rainbow come from raindrops spread in the atmosphere B. The raindrops act as prisms separating sunlight into spectrum of colors. C. The white clouds are like prisms which are composed of different colors of the rainbow D. When the incident light is reflected by the ground towards the clouds, it separates them into different colors. 13. What light phenomena results in a spectrum of colors that escapes when two reflections happened inside the water droplets? A. A primary rainbow C. A supernumerary bow B. A secondary rainbow D. A Halo 14. The reason why Hertz used the same length of wire from CA to CB. I. The voltage reached at the same direction. II. The voltage reached at the same point. III. The voltage reached at the same time. A. I only C. II and III only B. I and II only D. III only 15. Hertz’s observation on his experiment. I. When sparks flew across the main gap, sparks flew across the secondary gap. II. When sparks flew across the main gap, sparks stopped across the secondary gap. III. When sparks flew across the main gap, secondary gap do not ignite. A. I only C. II and III only B. I, II and III D. III only

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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.

Speed Slow Fast

Ball’s Speed Versus Path Observation of Ball’s Path

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

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 li...