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12 Physical Science Quarter 2: Module 1-4 1 DEVELOPMENT TEAM OF THE MODULE WRITERS: REGIN ARIAN V. SUBA, Teacher III CLARICE C. PASCUAL, Teacher II JOANN L. BALOLOY, Teacher I...
12 Physical Science Quarter 2: Module 1-4 1 DEVELOPMENT TEAM OF THE MODULE WRITERS: REGIN ARIAN V. SUBA, Teacher III CLARICE C. PASCUAL, Teacher II JOANN L. BALOLOY, Teacher I ABEGAIL L. CAPANGPANGAN, Teacher I JOVILYN G. ENOLPE, Teacher I ALFIN V. TURINGAN, Teacher I NATHALIE GAILE R. PANTOJA, Special Science Teacher I CONSOLIDATOR: JOVILYN G. ENOLPE, Teacher I LANGUAGE EDITOR: AMALIA A. MANLAPAO, Teacher I CONTENT MADONNA L. MADRIDANO, Master Teacher I VALIDATORS: MARJORIE A. NARIZ, Master Teacher I MARY ANN M. GUEVARRA, Teacher III MARHOUF JAY T. KUSAIN, Teacher I COVER PAGE AIRA MARI CON M. AUSTERO ILLUSTRATOR: TEAM LEADER: DR. RAQUEL M. AUSTERO Education Program Supervisor 2 How we come to realize that the Earth is not the Module 1 center of the Universe Most Essential Learning Competencies Explain how the Greeks knew that the Earth is spherical (S11/12PS-IVa-38) Cite examples of astronomical phenomena known to astronomers before the advent of telescopes (S11/12PS-IVa-41) Explain how Brahe’s innovations and extensive collection of data in observational astronomy paved the way for Kepler’s discovery of his laws of planetary motion (S11/12PS-IVb-44) What’s In The universe (Latin: universus) is all of space and time and its contents, including planets, stars, galaxies, and all other forms of matter and energy. While the spatial size of the entire universe is unknown it is possible to measure the size of the observable universe, which is currently estimated to be 93 billion light- years in diameter. In various multiverse hypotheses, a universe is one of many causally disconnected constituent parts of a larger multiverse, which itself comprises all of space and time and its contents; as a consequence, ‘the universe’ and ‘the multiverse’ are synonymous in such theories. The earliest cosmological models of the universe were developed by ancient Greek and Indian philosophers and were geocentric, placing Earth at the center. Over the centuries, more precise astronomical observations led Nicolaus Copernicus to develop the heliocentric model with the Sun at the center of the Solar System. In developing the law of universal gravitation, Isaac Newton built upon Copernicus' work as well as Johannes Kepler's laws of planetary motion and observations by Tycho Brahe. As the stars move across the sky each night people of the world have looked up and wondered about their place in the universe. Throughout history, civilizations have developed unique systems for ordering and understanding the heavens. Babylonian and Egyptian astronomers developed systems that became the basis for Greek astronomy, while societies in the Americas, China, and India developed their own. By the 5th century B.C., it was widely accepted that the Earth is a sphere. This is a critical point, as there is a widespread misconception that ancient peoples thought the Earth was flat. This was simply not the case. Eudoxus of Cnidus (4th century BCE) was the first of the Greek astronomers to rise to Plato’s challenge. He developed a theory of homocentric spheres, a model that represented the universe by sets of nesting concentric spheres the motions of which combined to produce the planetary and other celestial motions. Using only uniform circular motions, Eudoxus was able to “save” the rather complex planetary motions with some success. His theory required four homocentric spheres for 3 each planet and three each for the Sun and Moon. The system was modified by Calippus, a student of Eudoxus, who added spheres to improve the theory, especially for Mercury and Venus. Aristotle, in formulating his cosmology, adopted Eudoxus’s homocentric spheres as the actual machinery of the heavens. https://www.google.com/search?q=images+of+exodus+cinidus&sxs rf=ALeKk00P78WnyUXzcEhd50wdnGZoPLlauQ:1593407362214&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjnnrr- Aristotle was primarily concerned with the philosophical question of the nature of motion as one variety of change. He assumed that a constant motion requires a constant cause; that is to say, as long as a body remains in motion, a force must be acting on that body. He considered the motion of a body through a resisting medium is proportional to the force producing the motion and inversely proportional to the resistance of the medium. Aristotle used this relationship to argue against the possibility of the existence of a void, for in a void resistance is zero, and the relationship loses meaning producing the motions of the heavenly bodies. Aristarchus attempted to calculate the relative distance between the Earth and the Sun in the 3rd century BCE. He did this by measuring the angle between the Moon and the Sun during a half-moon and using trigonometry (discussed in Book II). Aristarchus concluded that the Sun is about 20 times further away than the Moon and must be about 20 times larger. This is because the Moon and Sun appear to be the same size. This is most evident during solar eclipses when the Moon blocks out the Sun completely. We now know that the Sun is almost 400 times further away than the Moon and it is about 400 hundred times larger. Ptolemy (flourished 140 CE) earth-centered or geocentric. It applied the theory of epicycles to compile a systematic account of Greek astronomy. He elaborated theories for each of the planets, as well as for the Sun and Moon. His theory generally fitted the data available to him with a good degree of accuracy, and his book, the Almagest, became the vehicle by which Greek astronomy was transmitted to astronomers of the Middle Ages and Renaissance. It essentially molded astronomy for the next millennium and a half. 4 https://amazingspace.stsci.edu/resource s/explorations/groundup/lesson/basics/g37/ Nicolaus Copernicus is sun-centered or heliocentric. He thought that the planets orbited the Sun and that the Moon orbited the earth. The Sun, in the center of the universe, did not move nor did the stars. It was the first to propound a comprehensive heliocentric theory equal in scope and predictive capability to Ptolemy’s geocentric system. Motivated by the desire to satisfy Plato’s dictum, Copernicus was led to overthrow traditional astronomy because of its alleged violation of the principle of uniform circular motion and its lack of unity and harmony as a system of the world. https://amazingspace.stsci.edu/resources/explorations/groundup/lesson/basics/g37/ During the 16th century the Danish astronomer Tycho Brahe, rejecting both the Ptolemaic and Copernican systems, was responsible for major changes in observation, unwittingly providing the data that ultimately decided the argument in favor of the new astronomy. Using larger, stable, and better-calibrated instruments, he observed regularly over extended periods, thereby obtaining continuity of observations 5 that were accurate for planets to within about one minute of arc—several times better than any previous observation. Several of Tycho’s observations contradicted Aristotle’s system: a nova that appeared in 1572. At the beginning of the 17th century, the German astronomer Johannes Kepler placed the Copernican hypothesis on firm astronomical footing. Converted to the new astronomy as a student and deeply motivated by a neo-Pythagorean desire for finding the mathematical principles of order and harmony according to which God had constructed the world, Kepler spent his life looking for simple mathematical relationships that described planetary motions. His painstaking search for the real order of the universe forced him finally to abandon the Platonic ideal of uniform circular motion in his search for a physical basis for the motions of the heavens. In 1609 Kepler announced two new planetary laws derived from Tycho’s data: (1) the planets travel around the Sun in elliptical orbits, one focus of the ellipse being occupied by the Sun; and (2) a planet moves in its orbit in such a manner that a line is drawn from the planet to the Sun always sweeps out equal areas in equal times. With these two laws, Kepler abandoned the uniform circular motion of the planets on their spheres, thus raising the fundamental physical question of what holds the planets in their orbits. He attempted to provide a physical basis for the planetary motions employing a force analogous to the magnetic force, the qualitative properties of which had been recently described in England by William Gilbert in his influential treatise, De Magnete, Magneticisque Corporibus et de Magno Magnete Tellure (1600; “On the Magnet, Magnetic Bodies, and the Great Magnet of the Earth”). The impending marriage of astronomy and physics had been announced. In 1618 Kepler stated his third law, which was one of many laws concerned with the harmonies of the planetary motions: (3) the square of the period in which a planet orbits the Sun is proportional to the cube of its mean distance from the Sun. Kepler's 1st Law: The Law of Ellipses. All planets orbit the Sun in elliptical orbits with the Sun as one common focus. https://www.britannica.com/science/Keplers-laws-of-planetary-motion 6 Kepler's 2nd Law: The Law of Equal Areas The line between a planet and the Sun (the radius vector) sweeps out equal areas in equal periods. In the diagram, the time interval t2-t1 = t4-t3 so the areas swept through in equal times are equal, that is A1 = A2. https://www.britannica.com/science/Keplers-laws-of-planetary-motion Kepler's Third Law: The Law of Periods or the Harmonic Law The square of a planet's period, T, is directly proportional to the cube of its average distance from the Sun, r T2 ∝ r3 or T2/r3 = k (1.1) where k is a constant and the same for all planets or orbital bodies (such as comets) in a given system. 7 What’s More Activity 1: Tycho Brahe and Johannes Kepler’s Innovation Answer the following questions briefly. Write your answer on a separate sheet of paper. 1. What was the most important contribution of Tycho Brahe to modern astronomy? ______________________________________________________________ 2. What are the proofs of Brahe’s statement that heavens are changing? ______________________________________________________________ 3. In your own opinion, what do you think of the astronomical units during the ancient time of Greeks and Indian philosophers? ______________________________________________________________ What I Have Learned Activity 1. Use the clues in the pictures to differentiate the theory of Ptolemy and Copernicus. Write your answer in the space provided below. https://www.brainpop.com/science/famousscientists/copernicus/ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ 8 What I Can Do Activity 1. Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper. 1. Which of the following state Kepler's three laws of planetary motion? A. Ptolemy law, Law of Ellipses, Motion law B. Harmonic Law, Motion Law, Ptolemy law C. Law of Equal Areas, Motion law, Law of Ellipses D. Law of Ellipses, Law of Equal Areas, Law of Periods 2. What do you call a constituent that is causally disconnected parts of a larger multiverse? A. Planets C. Jupiter B. Matter D. Universe 3. Who was responsible for one of the first Greek astronomical theories during the 5th century BC? A. Greek C. Indian B. Pythagoreans D. Keplers 4. During the earliest time, who developed the earliest cosmological models of the universe? A. Greek and Indian Philosophers B. Babylonians and Indian Philosophers C. Greek, Egyptian and Indian Philosophers D. Babylonian and ancient Greeks Philosopher 5. What do you call the universal model developed by Nicolaus Copernicus where the sun is the center of the Solar system? A. Heliocentric model B. Geocentric model C. Eccocentric model D. Homocentric model 9 Module 2 Aristotelian versus Galilean Views of Motion Most Essential Learning Competencies Compare and contrast the Aristotelian and Galilean conceptions of vertical motion, horizontal motion, and projectile motion. (S11/12PS -IVc -46) Explain how Galileo inferred that objects in vacuum fall with uniform acceleration, and that force is not necessary to sustain horizontal motion (S11/12PS -IVc -47) Explain the subtle distinction between Newton’s 1st Law of Motion (or Law of Inertia) and Galileo’s assertion that force is not necessary to sustain horizontal motion (S11/12PS-IVd-51) What’s In In the last module, you learned about the astronomical phenomena known to astronomers before the advent of telescopes and the spherical earth. Can you still remember the Brahe’s innovations and an extensive collection of data in observational astronomy paved the way for Kepler’s discovery of his laws of planetary motion? It is important that you have knowledge about motion. Terminology: Aristotelian versus Galilean Views of Motion In our modern world, we see many objects in our surroundings such as buses, trucks, bicycles, and cars moving around us, leaves falling from trees, and water flowing from the river. All of these objects are changing with their position. We all know that when an object changes its position, it is said to be in motion. Motion is the change in the location of an object over time. Motion is also described in terms of its direction, location, and speed. Aristotle’s Ideas of Motion Aristotle observed that a force is needed to produce motion. He suggested that to maintain the motion of force it must be continuously exerted on the object. He also added that if there is no force on it, there will be no motion. According to Aristotle, there are two types of motion. In Natural motion, the elements tend to seek their natural place. Violent motion is any force that opposes natural motion. 10 He believed that with the absence of external force, any moving object will eventually stop. Many people believed in the ideas of Aristotle regarding moving objects because they based it according to their observation in their daily life. A stone will fall back to earth to be with different rocks. Since a major stone has more “earth”, it http://www.drabruzzi.com/aristotelian_vs_galileian.htm will quickly fall compared to a feather. However, some situations do not require motion. There are cases of bodies that continue to move even without the presence of force acting upon it. Galileo’s Ideas of Motion Galileo challenged the idea of Aristotle regarding moving objects. For many years, people believed in the idea of Aristotle about motion nobody seemed to be successful in challenging the concept of Aristotle. He believed that objects move downward because of the gravity that disturbs their motion. Galileo tested the idea of Aristotle about motion through his “thought experiments” but this experiment was only on his mind. He did not perform this experiment. This experiment helped him to A arrive at his logical thought. When B a ball is released run down a bent rail, the ball rises which is nearly the same height as the original position. However, Galileo argued that with the absence of friction, an object will continue to move at a C constant speed along the straight line. As the inclined plane becomes steeper, the acceleration of the rolling ball increases. http://www.studyphysics.ca/2007/20/02_dynamics/20_Galileo_t heories.pdf 11 Galileo Inferred that Objects in a Vacuum Fall with Uniform Acceleration Do heavier objects fall faster compare to light objects? What do you think? According to Aristotle, if the two objects were released from a particular position, the heaviest will reach the ground first. He also believed that objects fell faster in the air than in water. Galileo disproved the idea of Aristotle about the falling objects by his reasoning and logical arguments. Galileo believed that with the absence of air resistance, the two objects will reach the ground at the same rate. A vacuum is an absence of matter in a system. Galileo demonstrated his experiments that when you dropped the objects simultaneously, they will reach the ground at the same time despite their masses and air resistance. He also discovered that objects fall with the uniform https://medium.com/intuitive-physics/galileos-leaning-tower-of- acceleration. pisa-thought-experiment-acceleration-due-to-gravity-is- independent-of-d8c5cf5cf1d Based on the story, Galileo dropped a small iron and large cannonball from the leaning tower of Pisa. The result was the two cannonballs were hit the ground at the same time. The spectators during that time were amazed by what they saw. He proved that objects with different weights fell at the same speed. Galileo did not attempt, however he clarify why a body continues to move at a constant velocity along a straight line. Inertia is the tendency of a body to remain in its state of rest or of uniform speed along the straight line. Galileo demonstrated that is normal for a moving body to do so, just as it is for a stationary body to remain at rest. Newton elaborated the idea of Galileo that all the bodies accelerate at the same rate regardless of size and mass. Isaac Newton created the Laws of motion. The first law of motion is what we called the Law of Inertia. The First Law states, "A body at rest will remain at rest, and a body in motion will remain in motion unless it is acted upon by an external force." The greater the mass of an object, the greater the inertia of an object has. 12 What’s More Activity 1: 4PICS 1 WORD Directions: There are four pictures presented below that are related to our topic. Analyze what specific word fits with the theme of the photos presented. Write your answer on the space provided. Answer: ____ ____ ____ ____ ____ O I S T W O V B X N H M https://4pics1word-answers.com/level-3244/ Activity 2: TRUE OR FALSE WITH A TWIST Directions: Mark each statement as true or false. Then shade in the squares that contain the numbers of statements that are true. The shaded squares will form the letters of an important word. You can use your pencil, ball pen, or coloring materials for the shading. Enjoy! ______1. Galileo believed that there were two kinds of motion called violent motion and natural motion. ______2. Galileo and Aristotle have opposing views about motion but they are a great help in scientific progress. ______3. Galileo suggested that force is necessary to produce motion. ______4. Galileo and Aristotle have the same perspective on the motion. ______5. According to Aristotle, every object in this world has a proper place. ______6. According to Galileo, the absence of friction makes the object move freely. ______7. Inertia is the movement or change in an area of an object over time. ______8. Motion is also described in terms of its direction, location, and speed. 2 5 8 3 8 5 8 7 2 3 2 5 6 1 2 3 1 5 3 2 8 2 7 2 5 8 6 7 4 4 2 7 1 3 6 7 5 1 7 3 6 5 7 5 7 6 1 4 1 6 7 3 2 5 8 7 6 3 4 1 8 4 2 8 7 1 8 7 2 8 4 8 3 1 7 2 2 4 7 1 5 4 2 7 1 4 5 7 2 3 1 7 2 3 1 2 1 6 1 1 4 5 7 1 8 6 2 3 6 5 2 1 6 3 6 2 5 4 5 4 7 6 7 2 5 5 1 6 5 8 13 Activity 3: Venn Diagram Directions: Using a Venn diagram, compare and contrast the Aristotelian and Galilean Motion. Aristotelian Galilean What I Have Learned Directions: Fill in the table below. Things I have learned 1. 2. 3. 1 question I want to ask 1. 14 What I Can Do You have learned the Aristotelian versus Galilean views of motion. For you to better understand the topic, read the article carefully and answer the questions. http://www.pas.rochester.edu/~blackman/ast104/aristotle_dynamics13.html Answer the following questions: 1. How do the views of Galileo and Aristotle about motion affect our understanding of the concept? ______________________________________________________________ ______________________________________________________________ 2. What is the importance of knowing the distinction between Newton’s 1st Law of Motion (or Law of Inertia) and Galileo’s assertion about force? ______________________________________________________________ ______________________________________________________________ 3. How does motion help us in our daily routine? ______________________________________________________________ ______________________________________________________________ 15 Module 3 Light, Reflection, and Refraction Most Essential Learning Competencies 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) 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 red light is used in photographic dark rooms, why we get easily sunburned in ultraviolet light but not invisible light, and how we see colors (S11/12PS-IVf-61) What’s In Light travels along a straight line. However, the spread of light in a straight line is only true as long as the light travels in a single medium. Light is a type of electromagnetic radiation which has a wavelength that the human eye can detect. It is a small part of the electromagnetic spectrum and radiation which stars like the sun give off. Light occurs in packets of tiny energy called photons. A photon is a particle of light. Each wave has its wavelength or frequency. Within a vacuum, the speed of light is 186,282 miles per second (299,792 kilometers per second), and in theory, nothing can travel faster than light. Light velocity is, well, more in miles per hour: around 670,616,629 mph. If you could travel at the speed of light, you could go around the Earth 7.5 times in one second. Three main processes generally occur when light passes between boundaries from one medium to another. They are absorption, reflection, and refraction. In absorption, the frequency of the incoming light wave is at or close to the electrons' energy levels in the matter. The electrons must consume the light wave's energy and change its state of energy. Two possibilities may occur next, either the electron returns to the ground state releasing the light photon or the matter retains the energy and the light is absorbed. Unless the photon is re-emitted immediately the photon will be reflected or dispersed efficiently. If the energy of the photon is absorbed, it usually shows itself as heating the matter. The absorption of light renders an object dark or opaque to the incoming wave wavelengths or colors: Wood is opaque to visible light. Many materials are invisible to certain light wavelengths, but they are visible to others. Glass and water are opaque to ultraviolet, but transparent to visible light. The structure and properties of the material can be understood by which wavelengths of light are absorbed by a substance. One way the absorption of light is apparent is by its color. If a material or matter absorbs light from certain spectrum wavelengths or colors, these colors will not be 16 seen by an observer in the reflected light. On the other hand, if the material contains those wavelengths of light, an observer will view them and see the object in certain colors. For instance, the green plant leaves contain a pigment called chlorophyll, which absorbs the spectrum's blue and red colors and represents the green leaves thus appear green. When a light ray hits a smooth polished surface like glass, water, or polished metal, and the light ray bounces back, it is called the reflection of light. Forms of Reflection On a smooth surface, light bounces at the same angle as it reaches the surface. Reflected light-rays move in the same direction for a smooth surface. This is known as specular reflection. Reflected light-rays disperse in all directions on a rough surface. It is known as diffuse reflection. Specular Reflection refers to a transparent, sharp reflection, much like those, you get in a mirror. A mirror is made of glass surrounded by a uniform film of highly reflective material like paint. This reflective surface uniformly reflects nearly all the light incident at it. There isn't much difference between different points in the angles of reflection. This means the haziness and the blurring are gone almost entirely. Figure 1 https://byjus.com/physics/reflection-of-light/ 17 Figure 2 https://pt.slideshare.net/PatriciaMartinez19/particle-theory-of-light Reflective surface other than mirrors has a very rough texture. It can be attributed to wear and tear on the surface such as cracks and dents, or dirt. Sometimes even the material which makes up the surface matters. All of this leads to a loss of both reflective brightness and efficiency. In the case of these rough surfaces, the angle of reflection is entirely haphazard when compared between points. For rough surfaces, the rays incident is mirrored in entirely different directions at slightly different points on the surface. This form of reflection is called diffused reflection, which is what makes it possible for us to see non-shiny objects. Refraction is the bending of light as it moves from one transparent material to another (it often happens with wind, water, and other waves). This refractory bending helps us to have lenses, magnifying glasses, prisms, and rainbows. Even this bending of light depends on our eyes. We wouldn't be able to focus light on our retina without refraction. If light passes at an angle to a material with a particular refractive index (optical density), it refracts. This change in direction is due to a change in velocity. As light, for example, travels from the air through water, it slows down, allowing it to continue traveling at a different angle or direction. 18 Figure 4 Figure 5 https://pt.slideshare.net/PatriciaMartinez19/particle-theory-of-light https://www.stickmanphysics.com/stickma n-physics Using the particle theory and the wave theory of light, many phenomena observed in everyday life are explained. Some of these are: 1. Reflection can be explained using the wave nature of light. The reflected light incident to the reflective surface at an angle between 1 degree and 89 degrees is slightly distorted because the waves parallel to the reflective surface are more reflective than other waves. The theory of light particles can also describe reflection by comparing its reflection on a smooth surface with a ball thrown against a smooth wall that bounces much like the way light is reflected. 2. Refraction of light is explained using the wave nature of light. This also occurs during polarization. Crystal surfaces such as calcite show double refraction, a light beam are divided into two beams. Light is propagated at different velocities in some substances. Newton uses the rolling-ball model to explain refraction. When a ball is set to roll over a higher surface at a given angle with the normal to the edge, the ball rolls over the lower surface at a smaller angle with the normal one at the inclined side. This is just like what happens when there is an incident of a light ray with the boundary between media at some angle. 3. The propagation of light was explained by both the wave theory and the particle theory. Huygens clarified the straight line of light transmission using a stone that fell into a pool of water. The stone disrupted in the water. It produced a series of intense waves moving from the point of impact, while the stone comes to rest quickly at the bottom of the pool. Newton clarified this straight line of light propagation by using shadow forming as the light reaches an object and the shadows provide proof of the straight line of light propagation. Photon is a particle of light defined as a discrete bundle (or quantum) of electromagnetic (or light) energy. Photon travel at the vacuum speed of light ( more commonly just called the speed of light) of c = 2.998x 10 m/s. Can be destroyed/created when radiation is absorbed/emitted. Can have particle-like interactions (i.e. collisions) with electrons and other particles, such as in the Compton 19 Effect in which particles of light collide with atoms, causing the release of electrons. This means that a higher frequency light has more energy than a lower frequency light. Light is a stream of moving photons. Blue light has a frequency of 6.5 x 10 Hz, red light has a frequency of 4.00 x 10 Hz. The number of photons in a stream determines if the light is dim or intense. Intense light has a lot of photons while dim light has only a few photons. This is the reason why red light is used in a photographic darkroom. Red light has a very low frequency, so, its number of photons is very few. The photographic film will not be exposed too much in using red light. Ultraviolet light has a very high frequency. It is very energetic due to the large number of photons it contains. Because of this, it is easy to be sunburned when exposed to UV light. Visible light has a lower frequency than UV light, so it is not easy to get burned by visible light. Light also creates the color spectrum. The visible spectrum of color is seen when the light passes through a prism. This separates twelve visible colors from each color found in the light. There are eight main colors within these twelve, which are those with their wavelengths. The four remaining colors can be distinguished, but they are within the main color wavelength boundary. The spectrum of colors also exists without the help of prisms. Prisms let's see all the colors at once. When white visible light wavelengths naturally come into contact with matter, the matter absorbs a certain amount of light (depending on its type). What is not processed is reflected out and is referred to as a color. The object always absorbs as much light as possible. Therefore, when someone sees something red, it means that the object has absorbed every other wavelength of light and just reflected the red wavelength. If something is white it means that all the wavelengths have been absorbed and all the wavelengths have been reflected when it is black. When the radiation is absorbed and comes into vision, it is drenched in the retina utulizing photoreceptors. There are two photoreceptor types: rods, and cones. Rods see shades of gray, and the cones are the only receptors associated with color vision. This is because inside the cones there is a pigment that allows that receptor to interpret the color in a way that the brain can understand. As there are several cone receptors, each receptor falls into one of these three categories: the form that has red pigment and takes red light which is the majority of the receptors in the human eye — the type that takes green light, and then blue light which makes up just around 2% of the total receptors throughout your body. When the photoreceptors process the light, they categorize how much is present in the radiation of each form. Instead, how much of each color is added to shape the color inside your eyes. The difference in cone quantity between the forms is important because it influences how much we see of each type of color. When someone has poor vision, the first thing that becomes blurred is usually the color blue, as there are fewer cones, and the last color that is hard to see is red. 20 What’s More Activity 1: Describe Me! Directions: Describe the three different processes generally occur when light passes between boundaries. LIGHT REFLECTION REFRACTION Activity 2: Paint in Words! 1. Why red light is used in photographic dark rooms? 21 2. Why do we get easily sunburned in ultraviolet light but not invisible light? 3. How do we see colors? What I Have Learned EXIT CARD What will happen if there is no light? ____________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ ________________________________________________________ 22 What I Can Do Create a poster slogan on the importance of light. 23 Module 4 Most Essential Learning Competencies Cite experimental evidence showing that electrons behave like waves (S11/12PS-IVg-64) Differentiate dispersion, scattering, interference, and diffraction (S11/12PS- IVg-65) What’s In Subatomic particles that compose an atom are electrons, protons, and neutrons. Electrons are found outside the nucleus of an atom while protons and neutrons are found inside the nucleus of an atom. The electrons rotate in orbits of different energy levels forming a cloud around the nucleus. Recent discoveries about atoms reveal that electrons can behave like waves. One of the essential characteristics of waves is exhibiting interference effects. Many experimental shreds of evidence show that electrons behave like waves. Photoelectrons are ejected with a certain maximum kinetic energy that increases in proportion to the light-wave frequency in photoelectric experiments. Compton scattering experiment or also called the Compton Effect shows the wave characteristics of electrons. It is the result of a high-energy photon colliding with a target, which releases loosely bound electrons from the outer shell of the atom or molecule. The scattered radiation experiences a wavelength shift that cannot be explained in terms of classical wave theory, thus lending support to Einstein's photon theory. It was first demonstrated by Arthur Holly Compton in 1923 and he received a Nobel Prize in 1927. The effect is important because it demonstrates that light cannot be explained purely as a wave phenomenon. Light of sufficient intensity for the electric field to accelerate a charged particle to a relativistic speed will cause radiation- pressure recoil and an associated Doppler shift of the scattered light, but the effect would become arbitrarily small at sufficiently low light intensities regardless of wavelength. It convinced physicists that light can behave as a stream of particles whose energy is proportional to the frequency. images.search.yahoo.com/comptoneffects 24 Bohr atomic model, by Niels Bohr a Danish physicist in 1913, proposed the description of the structure of atoms, especially that of hydrogen. The Bohr model of the atom was the first that incorporated quantum theory and was the predecessor of wholly quantum-mechanical models. The Bohr model and its successors describe the properties of atomic electrons in terms of a set of allowed values. Atoms emit or absorb radiation when the electrons abruptly jump between allowed or stationary states. Direct experimental evidence for the existence of such discrete states was obtained by James Franck and Gustav Hertz, German-born physicists in 1914. Also, De Brogle showed that in a Bohr atom the wave properties of electrons are dominant. images.search.yahoo.com/bohratomicmodel How dispersion, scattering, interference, and diffraction are different from one another? Dispersion The index of refraction of a particular material is dependent on the frequency or speed of light in that material. When light passes through a medium such as a glass prism, it separates into different colors of red, orange, yellow, green, blue, indigo, and violet, they will be refracted through different angles because the light is dispersed into colors by the material. Since white light is composed of different colors of different wavelengths, the color bend at different angles thus separating white light into different colors. images.search.yahoo.com/dispersionofwhiteligh 25 Scattering This phenomenon occurs when light is absorbed and reradiated by particles in the air or it is the change of motion of a particle due to its collision with another particle about the size of gas molecules. When initially unpolarized sunlight strikes a molecule, electrons are accelerated and vibrate vertically and horizontally then reradiated as polarized light. Blue and violet colors are scattered the most while red and orange are scattered the least. The longer paths of the blue and violet colors in the atmosphere during sunset make red and orange dominant colors during sundown. images.search.yahoo.com/scatteringoflights Interference An English physician, Thomas Young, found out that light exhibits interference effects in his famous double-slit experiment. When light emerges from the two slits and arrives at a point on the screen, they either combine constructively or destructively. Bright lines appear on the screen when they combine constructively and dark lines appear on the screen when they combine destructively. It is the net effect of a combination of two wave trains that are overlapping each other. The following conditions are examples of interference patterns: 1. Light shining on a slick of oil in the pavement produces vivid colors. 2. Light shining on soap bubbles yield the colors of the rainbow. 3. Light shining on compact discs produces vivid colors. 26 images.search.yahoo.com/imagesoflightinterference Diffraction Have you seen a rainbow after the rain? Light plays an important role in the formation of a rainbow. According to the Huygens-Fresnel principle, every point on a wave behaves like a source. Light behaves like waves and when this light wave encounters obstacles with a small gap, waves start propagates from that gap. Light bends as it passes through the edges of obstacles or barriers through small openings. This property of light is not easy to observe because the bending is very small, the common way of observing this interference patterns of deviated light coming from a single slit on screen. Diffraction patterns are usually viewed with the use of diffraction gratings of about 6000 lines up to 10 000 lines consisting of a large number of parallel, equally spaced lines or openings on a plastic sheet. We can say that diffraction and interference are closely related. We tend to call it diffraction, when there are many sources of a wave, are used and interference if few wave sources are considered. Examples and application of diffraction in real life 1. bending of light at the corners of the door 2. CD reflecting rainbow colors 3. the sun appears red during sunset 4. shadow of an object 5. holograms 6. X-ray diffraction 7. spectrometer 8. to separate white light 27 images.search.yahoo.com/diffractionoflight Hologram diffraction of sunset light through trees 28 What’s More Activity 1: Match Me! Match Column A with Column B. Write the letter of your answer on the space provided before the number. Column A Column B _____1. Photoelectric effect a. electrons, protons, and neutrons _____2. Electrons b. Niels Bohr _____3. Bohr atomic model c. photoelectrons are ejected with a certain maximum kinetic energy _____4. Subatomic particlesn d. found inside the nucleus of an atom _____5. Protons and neutrons e. found outside the nucleus Activity 2: Write fact if the statement is correct and bluff if the statement is wrong. Write your answer on the space provided before the number. _____1. Electrons, protons, and neutrons are the subatomic particles that composes an atom. _____2. Protons and neutrons are found outside the nucleus of an atom. _____3. Electrons are found inside the nucleus of an atom. _____4. There is no experimental evidence showing that electrons behave like waves. _____5. When unpolarized sunlight strikes a molecule, electrons accelerated and vibrate vertically and horizontally then reradiated as polarized light. _____6. The index of refraction of a particular material is independent to the frequency or speed of light in that material. _____7. According to Thomas Young, light exhibits interference effects in his double-slit experiment. _____8. When light passes through a medium such as a glass prism it does not separate. _____9. Diffraction is the bending of light as it passes through a small opening of the edges of barriers. _____10. One of the most essential characteristics of waves is exhibiting interference effects. 29 What I Have Learned Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper. 1. Which one of the following is most essential for observing the diffraction of light? A. monochromatic light C. a very narrow slit or obstacle B. white light D. two coherent sources 2. Which of the following principles is responsible for Youngs double-slit experiment? A. reflection C. interference B. dispersion D. refraction 3. Colors in a soap bubble or an oil slick on the road are caused by: A diffraction C thin Film Interference B polarization D light intensity change 4. Light travels fastest in A glass C air B diamond D vacuum 5. The process of waves appearing with different intensity at a point when several waves pass through a point in a medium is known as A. interference C. polarization B. diffraction D. all of the above What I Can Do A rainbow occurs after the rain, explain in your understanding how light plays an important role in the formation of a rainbow. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 30 31 MODULE 2 MODULE 1 Activity 1 1. motion Activity 1 Activity 2 A 1. False A A 2. True C D 3. False 4. False 5. True 6. True 7. False 8. True Activity 3 *Answer may vary Answer Key 32 MODULE 4 MODULE 3 Activity 1 Activity 1 C *ANSWER MAY VARY E B Activity 2 A *ANSWER MAY VARY D Activity 2 fact bluff bluff bluff fact bluff fact bluff fact fact What I have Learned C C A D D Answer Key
