Sciences Subject (BS 21001)

301 Light absorption Light absorption is the light absorbed when travels through the media. As energy of light is transferred to the surface material, it will create heat, for example, solar ovens and solar- powered water boilers. Moreover, the property of absorption can be applied to our daily life, for instance, choosing to wear white clothes will absorb less light than wearing black clothes. As you are wearing black outfits in the sun, it would be warmer than white clothes. Interference Interference occurs when two rays of light meet while traveling along the same medium and join together or cancel each other out. The light will be brighter if the two rays of light join together. On the contrary, if they cancel out each other, the light will be less brightness. The advantages of interference are cameras, video projectors, and reducing light reflection. In case of lightening up will be used as a reflector. 3.8 Lens The image formation for plane mirrors and lenses A plane mirror is flat which has the other side reflecting the light. Therefore, the image formed by a plane mirror is virtual appearing to be behind the mirror. A virtual image has the same distance and same size as the object. Additionally, the image is laterally inverted which means left and right side is reversed and same as the object. Figure shows the image formation for a plane mirror. The formula to calculate the number of images produced by 2 plane mirrors aligned in a certain angle is:

302 Where n = the number of images formed  = the given angle If a result of n is fractional, it will be rounded to 1. Example 1 The two plane mirrors are aligned at a 60-degree angle. Calculate the number of images formed. Solution Answer n=5 is 5. = 5 images The number of images formed by two plane mirrors that are aligned in a certain angle Spherical mirror There are 2 types of spherical mirrors: Concave and convex mirrors. 1. Concave mirror is a curved mirror reflecting light inward or a mirror that the incident ray and the reflected ray reflect on the same side as the center of curvature. As shown in the figure below. Figure shows the incident ray and the reflected ray of a concave mirror. 2. Convex mirror is a spherical reflecting surface in which its bulging side faces the source of light. The incident ray and the reflected ray are on the other side of the center of curvature. As shown in the figure below.

303 Figure shows the incident ray and the reflected ray of a convex mirror. Images formed by placing an object in front of a curved mirror are generally both real and virtual images. A real image is always located in front of the mirror while a virtual image is located behind it. The concave mirror produces either real or virtual images. The sizes of images including bigger, same, and smaller depend on the distances of objects. The convex mirror can make only a virtual image which is smaller than the object. Note An image is formed by striking or virtually striking of the rays of light which reflect off of a mirror or deviation of the rays through a lens. There are two types of images; 1. Real image is the rays of light striking. It is located in front of a mirror or behind a lens but there must be a screen for viewing the object. The image appears inverted. Besides, the sizes are bigger, same, and smaller. The sizes of objects relate to the distance of objects, like the image appears on the screen etc. 2. Virtual image is caused by the virtual light rays striking. The image is located behind a mirror or in front of a lens. You can view the image without a screen. The virtual image is upright such as an image produced by a magnifying glass etc.

304 The table shows the sample benefits of concave and convex mirrors Concave Mirror Convex Mirror 1. Dentists used concave mirror to examine 1. Used in cars or motorcycles as rearview their patient’s teeth in order to see enlarged mirrors or side-view mirrors for a wider angle image of teeth. of view comparing to plane mirrors. 2. Used in microscopes to collect light for 2. Installed around corners in order to see magnifying a slide to see the image more around blind corners. clearly. Lens Lenses are transparent objects with curved surfaces, made of glass or plastic. There are two types of lenses called convex and concave lenses. Convex lens A convex lens is thick in the middle and thin on the ends. As shown in the figure below. Figure shows the characteristics of convex lenses. Figure shows the important parts and the light rays of a lens.

305 A convex lens is to collect parallel rays of light to converge at one point. The lines or directions of light passing through lenses can be represented by the rays of light. If light travels from the distant places such as the Sun or other stars, the distances are called ‚infinity‛. Light will emit parallel rays. When the parallel rays of light pass through a convex lens the refracted rays converge at one point called the ‚principal focus‛ (F). The distance between the principal focus and the center of the lens is called the ‚focal length‛ (f). Plus, a straight line drawn through the center of curvature and the middle of the mirror’s surface is defined as the ‚principal axis‛. Images formed by convex lenses Images formed by convex lenses are the rays of light refracted, then converging at one point. The convex lenses produce both real and virtual images depending on the positions of objects placing in front of lenses. As shown in the figure below. Figure shows the real and virtual images formed by convex lenses. (A) An image is formed when an object is further from a convex lens than the focal length. (B) An image is formed when an object is closer to a convex lens than the focal length. Figures show the example of image formed at the different positions of convex lenses.

306 Concave lens A concave lens is thinner at the center than at the edges. As shown in the figure below. Figure shows the characteristics of concave lenses. The rays of light that pass through a concave lens are spread out as shown in the figure below. Figure shows the image formed by a concave lens when the objects are placed at the different distance. To determine the types and the position of the image by calculation The position of the image as stated above has been determined by drawing a diagram of rays. However, there is the other way to identify the position that is the calculation. The formula is as shown below. Formula Where f = focal length s = the distance of object s'= the distance of image

307 Formula m = I/O = s'/s Where m = magnification of lens I = image height O = object height In order to calculate the position and types of images, there must determine the symbol of + and – in the equation. 1. s is + objects located in front of lenses, and s is – objects located behind lenses. 2. s' is + objects located in front of lenses, and s' is – objects located behind lenses. 3. f of convex lenses is +, and f of concave lenses is –. Example 2 An object is placed 12 cm from a convex lens. If the convex lens has a focal length of 5 cm, what type of image does the convex lens form? Where is the image formed? Solution Formula 1/f = 1/s + 1/ s' Determinef = 5 cm, s = 12 cm 1/5 = 1/12 + 1/ s' 1/ s' = 1/5 + 1/12 = 12/60 – 5 /60 1/ s' = 7/60 s' = 60/7 = 8.6 cm Answer s' is a positive, therefore the image is real that is 8.6 cm from the convex lens. 3.9 The advantages and disadvantages of light The advantages of light Light is one form of energy which is everywhere and has no weight. However, light can work. Additionally, the sunlight consists of several light waves as stated above. The benefits of sunlight are divided into 2 parts that are heat and bright light. In our daily life, we benefit from the

308 heat and bright light from the sun. The sunlight makes our days bright which help us to do activities easily. Several careers have to use the sun’s heat in their work. Even though the sun sets, the ground which absorbs the heat during the day keep us warm at night. The benefits of light are classified into 2 categories; direct and indirect benefits. The sunlight helps to dry clothes faster. Salt farming 1. The direct benefits of light including salt farming, drying food, drying clothes, killing germs in drinking water are dependent upon the sun’s heat. Moreover, shadow puppets and movies use light to cast shadows onto the screens. The visualization also takes into account the advantages of light. 2. The indirect benefits of light are in the parts of the water cycle (the formation of rain). Furthermore, both edible plants and animals collect energy from the sun. The disadvantages of light 1. If you look at the high intensity of light for a long time, you may damage your eyes. 2. The overexposure of high intensity light can cause you sunburn and contribute to skin cancers. 3. When the sun emits light too much, it will influences global warming and be harmful to living things.

309 Topic 5 Heat energy and the origin source Experimental Activity: When light passes through a lens. Objectives After the experiment, student are required to 1. Describe that when rays of light pass through a convex lens, they converge. 2. Describe that when rays of light pass through a concave lens, they diverge. 3. Describe that a magnifying glass is used to focus light. 4. Use a magnifying glass to magnify a variety of objects. Main Concept 1. The property of convex lenses is to converge rays of light. 2. The property of concave lenses is to diverge rays of light. 3. An important component of a magnifying glass is a convex lens which helps to focus light and magnify objects. Experimental tools 1. White paper 2. Convex lens 3. Concave lens 4. Light box 5. Low voltage transformer 6. Electrical wiring with power jack 7. Lighting channel sheet: 1 lighting channel 8. Lighting channel sheet; 5 lighting channels. 9. Magnifying glass

310 Experimental procedures 1. Put a convex lens on white paper which is on the table. Place a flat side of the lens toward the paper. Then, draw a line around the lens on the paper. 2. Insert a sheet of 5 lighting channels into a gap of a light box. Then, connect a light box to a 12-volt low voltage transformer. After that, place a light box far from a convex lens moderately. 3. Dot a line along the beams of light and draw the lines of the incident ray and the refracted ray. 4. Repeat the procedures by changing the angles of the incident rays. Draw the lines of the incident rays and the refracted rays. 5. Adjust light from a light box with a 5 light channel sheet to pass through a convex lens. Observe the lines of light beams entering the lens. Draw the incident rays and the refracted rays representing the three beams of light. 6. Repeat No.5. But change from a convex lens to a concave lens and change the white paper to the new one. 7. Compare the 5 beams traveling through a convex lens and a concave lens.

311 8. When passing light through a convex lens and a concave lens. After that, use a magnifying glass to focus the sunlight. Place a magnifying glass 2 cm above the ground. Then, increase the distances and observe the brightness on the ground. 9. Adjust the height of a magnifying glass till you get the brightest light on the ground. Repeat the procedures, but change to a concave lens. 10. Use a magnifying glass to view letters. Adjust the distance between a magnifying glass and letters. Observe the change of letters viewing through a magnifying glass. Experimental results 1. Draw rays of light entering a convex lens and a concave lens. Convex lens Concave lens 2.When use a magnifying glass to focus the sunlight, what kind of image is formed? ……………………………………………………………………………………………………… ………………………………………………………………………………………………………

312 Conclusion ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… Experiment: The separation of colors in the sunlight Objectives Students can conduct an experiment and conclude the colors of sunlight. Main concept Sunlight consists of a variety of colors. Experimental tools

313 1. Triangular prism 2. A white screen 3. A wash bowl 4. A mirror Experimental procedures 1. Hold a triangular prism up to the sun. Move a prism from until you can see the reflection of colors on a white screen and record the data. 2. Look through the prism by placing it near your eye and look at the sides of prism. Turn it toward the light. Do not look at the sun. Record the observations. 3. Pour water in a wash bowl until the bowl is almost full. Put a mirror in the bowl of water by leaning a mirror against the edge of the bowl.

314 4. Place the bowl in the sun. Move the mirror from side to side until you can see the reflection of colors on a sheet of paper which is located above the bowl. Experimental results Observations Experiments 1. Hold a triangular prism up to the sun. 2. Look through the prism. 3. Look at the screen. Conclusion ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………….

315 Experiment: The formation of rainbow Objectives Students are required to 1. Conduct experiment and conclude the formation of rainbow. 2. Explain that a rainbow is seen by always turning your back to the sun. Main concept A rainbow is formed after or before it rains. When the sunlight enters lots of water droplets in the air. Experimental Tools A foggy spray bottle filled a half full of water. Experimental procedures 1. Stand outside and turn to the sun. Then spray a foggy spray bottle (filled a half full of water). Observe and record the data.

316 2. After that, turn your back to the sun. Spray a bottle. Observe water droplets. Record the result. Experimental results ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… Conclusion ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………

317 Experiment: The formation of shadow Objectives Students are required to 1. Describe the formation of shadow. 2. Explain the relationship between an object and a shadow from the experiment. 3. Apply the knowledge of shadow. Main concept 1. When an object block the path of light, light couldn’t travel through the other end. Then, it causes the dark area on a screen called a shadow. 2. The shape of a shadow depends on the object that is casting it. 3. A shadow can change in shapes and positions. 4. The partial shadow is called penumbra. 5. The complete shadow is called umbra. Experimental tools 1. The objects with a variety of shapes (e.g. a rectangular shape plastic object, frosted glass, a play dough modeling compound, a plastic bar, a dry cell, a ball.) 2. A screen

318 3. A light box 4. A low voltage transformer 5. An electrical wiring with 2 power jacks Experimental procedures 1. Place a light box to a distance of 15-20 cm from a screen as shown in the figure below. Turn on a light box, and then observe the brightness on a screen. 2. Put a ball between a light box and a screen. Align a ball in a light bulb of a light box and a screen. Observe the brightness on a screen. 3. Move a ball toward a screen. Observe the brightness on a screen. 4. Place a ball about 10 cm away from a screen. Then, move a screen toward a ball. Observe the brightness on a screen. 5. Repeat step 2-4. Change from a ball to a rectangular shape object.

319 Experimental results ……………………………………………………………………………………………………… ….…………………………………………………………………………………………………… ……………………………………………………………………………………………………… …….………………………………………………………………………………………………… Conclusion ……………………………………………………………………………………………………… ….…………………………………………………………………………………………………… ……………………………………………………………………………………………………… …….………………………………………………………………………………………………… Experiment: Eyes and Vision Objectives Students are required to 1. Describe the components of eyes relative to the vision. 2. Identify the functions of eye components relative to the vision. 3. Conclude the experiment that two eyes give a better depth perception than one eye. 4. Describe the importance and the ways to take care of eyes. Main concept 1. The important components of eyes are cornea, iris, pupil, and retina. 2. Eyes play an important role in vision. Therefore, it is crucial to take care of your eyes.

320 Experimental tools 1. The figure of eye components 2. 2 pencils Experimental procedures 1. Pair up to observe your friend’s eyes. 2. Compare his eyes to the figure of eye components. 3. First try, close your left eye and try to move the two pencils, which place 10 cm away from each other, to hit each other. Try to touch the ends of pencils together. Record the result. 4. Second try, close your right eye and repeat step 3. Record the result. 5. Third try with your both eyes open and repeat step 3 and step 4. Observe and record the result. Experimental Results ……………………………………………………………………………………………………… ….………………………………………………………………………………………………….… ……………………………………………………………………………………………………… ….………………………………………………………………………………………………… Conclusion ……………………………………………………………………………………………………… ….…………………………………………………………………………………………………… ……………………………………………………………………………………………………… …….…………………………………………………………………………………………………

321 The exercise of Lesson 12 Direction Choose the best answer to each question and mark the letter A, B, C, or D on your answer sheet. 1. Which one of these is clean energy? A. Energy from coal B. Solar energy C. Energy from fuels D. Biological energy 2. What is the component of sunlight? A. Heat B. Light C. Dust D. Both A. and B. are correct. 3. How does a solar cell work? A. Convert electrical energy into mechanical energy. B. Convert solar energy into mechanical energy. C. Convert solar energy into electrical energy. D. Convert mechanical energy into electrical energy. 4. Which careers do they use the benefits of light directly? A. Salt farming B. Trading C. Fishing D. Livestock farming 5. If a classroom is dark, what is the first thing you should do? A. Turn on the lights. B. Open the door and windows. C. Start a fire. D. Learn outdoors. 6. Which show is related to the light most? A. Antiphonal singing B. Dancing C. Southern folk singing D. Shadow puppet 7. Plants use light to make food -> animals eat plants-> humans eat animals. What is this statement represented to? A. Natural law B. Retaliation C. Natural Balance D. Energy transmission

322 8. Which one of these should not be done? A. Point a finger at a rainbow. B. Make hand shadows from a lamp or a bulb. C. Stare at the sun for a long time. D. Put on sunscreen when you go to the beach. 9. What types of energy is light energy converted into? A. Mechanical energy B. Electrical energy C. Sound energy D. Wind energy 10. Which one is correct? A. Solar energy doesn’t cause any pollution. B. The sun gives light in the day time. C. The earth is the only planet that the sun gives light to. D. The sunlight can’t kill germs.

323 Answer 1. B 2. B 3. C 4. A 5. B 6. D 7. D 8. C 9. B 10. A

324 Lesson 13 Stars and Life Essence Groupd of Zodiac stars, fixed star of servation and seraching for stars from a starmap including the usefulness of fixed stars Expected Learning Outcome: Learners are 1. able to identify the groups of Zodiac stars 2. able to explain how to find ‚Polaris/The North Star‛ 3. able to use the starmap 4. able to explain the use of fixed stars for their ways of living Scope of Contents Topic1: Groups of Zodiac stars Topic2: Fixed stars of servation Topic3: How to find ‚Polaris/The North Star‛ Topic4: Starmap Topic5: How to make use of fixed stars

325 Topic1: Groups of Zodiac stars The meaning of fixed stars Fixed stars refer to bright stars which can produces energy by themselves by changing some mass (m) at the core of the stars to energy (E) as in Einstein’s equation E=mc2. C is the speed of light which is almost 300,000 kilometers per second. The change from the mass to energy of fixed stars occurs at the temperatur of 15,000,000 Kelvins to melt Hydrogen into Helium. This reaction is called ‚Thermonuclar‛. The stars that can produce this type of energy have enormous mass, so do the fixed stars. The sun, one of the fixed star, has 200 million million million million tons which is 98% more than other masses in the solar system. However, other fixed stars are far away and can be seen like a spot of light through a large telescope. Our neighbouring fixed star is called ‚Alpha Centauri‛ which is composed of three fixed stars orbiting each other and in the groups of stars which are close to the sun called ‚Proxima Centauri‛ of which its distance is 40 million million kilometers away or 402 light years (1 light year = the distance the light travel in a year or 9.5 million million kilometers). There are some planets orbitting some fixed stars like the sun. This is called ‚extra solar system‛. Relation between the earth and the sun The sun is the nearest star located in the middle of the solar system orbited by a number of planets as natural satellites. Its core temperature is as high as 15 million Kelvin which is high enough to make 4 hydrogen nucleuses melt into 1 helium nucleus. The surface temperature is 5,800 Kelvin which is significantly lower than that of the core. The sun has a diameter of 1.4 million kilometers (around 9 times of the earth’s). The earth is one of the planets in the solar system orbiting around the sun in an oval shape. The average distance between the earth and the sun is 149,597,870 kilometers and the orbital period is one year. Observed from the earth surface, the sun rises in the east and sets in the west everyday; this is due to the earth’s revolving period of 1 day. However, if one regularly observes the sunrise and sunset, he will find that the sun will exactly rise in the east and set in the west only for 2 days, the 21st of March and the 23rd of September. The sun ordinarily rises or sets in a direction that is slightly either to the north or south. The 21st of June is the day that the sun rises and sets in the furthest north direction while the 22nd of December is the day that the sun rises and set in the furthest south direction, as shown in Figure 1.

326 Figure 1 Sunrise and sunset positions are changing every year Changing in the sunrise-sunset position is generally the result of the earth’s orbital period of a year around the sun. It can be seen, from the earth’s horizon, that the sun moves into the same direction with the direction that the earth orbits around the sun. The earth moves along to the east, passing through the zodiac stars according to Figure 2 which includes Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricornus, Aquarius, and Pisces. The sun will appear in the position to the east passing through these stars making the observer see stars in the sky 4 minutes sooner everyday, which means in 1 day the position of the sun will change for 1 degree or 1 year for each zodiac rotation.

327 Figure 2 the 12 zodiac stars and the earth orbit around the sun that makes the observer notices the sun change its position according to the zodiac stars. The path of the sun through the zodiac stars is called the ‚Ecliptic‛. The position of the sun on the ecliptic path on the 21st of March is referred to as the ‚Vernal Equinox‛ while the position on the 23rd September is called the ‚Autumnal Equinox‛. Whenever the sun positions itself into these two spots, the sun will precisely rise in the east and set in the west and the daytime and nighttime will be equal. The sunrise-sunset path in the day of the Vernal Equinox is called the ‚Celestial Equator‛. The position of the sun on the 21st June ecliptic path is known as the ‚Summer Solstice‛ in which the sunrise-sunset will take place furthest to the north. In the northern hemisphere, the daytime will be longer than the nighttime (summer season). In contrast, the position on the 22nd December ecliptic path is called the ‚Winter Solstice‛ in which sunrise-sunset position will go furthest to the south. In the northern hemisphere, the nighttime will be longer than the daytime and it will be winter. Seasons happen because the earth’s axis being tilted to its orbital plane by an angle of 23.5 degrees while it orbits around the sun. On the 21st of June, it is summer in the northern hemisphere and winter in the southern hemisphere. On the other hands, on the 22nd December it is summer in the southern hemisphere and winter in the northern hemisphere. This information is provided in Figure 3. Seasons result from each different part of the earth is exposed to a different amount of sunlight during the year. Figure 3 The earth’s axis being tilted to its orbital plane by an angle of 23.5 degrees which causes seasons in the earth

328 When the sunlight reaches an object there will be a shadow. If we put in a stick upright into the flat plain, its shadow will appear on the ground after being shone by the sunlight. Both the length and direction of the shadow will noticeably change from time to time. Considering Figure 4 when the sun rises from the east in the morning, the shadow of the stick lies to the west. While the sun moves higher into the sky, the shadow becomes shorter and starts to turn to the north. When the sun appears on the Meridian Trail (the highest position of the sun in the sky), the shadow becomes shortest and turns towards northern-southern direction. In the afternoon where the sun moves into the west, the shadow appears to be longer and turns from the north to the east. Figure 4 (a) the shift of stick’s shadow caused by the different positions of the sun (b) A geometric figure indicating an appearance of shadow on the ground Due to the fact that the daily sunrise-sunset position varies each year, the appearance of stick’s shadow is not be in the same line and length. When the sun appears on the Meridian Trail, however, the shadow will always become shortest and lie itself in the north-south direction. Furthermore, it is evident that for some days when the sun appears exactly above the observer along the Meridian Trail, like in Chiengmai; at noon on 15 May and 30 July, there is not any shadow of the materials on the ground. In Bangkok, the sun is above the head at noon on 28 April and on 16 August. The change of the shadow in a day is like the house hand of the clock when we can locate appropriate seales of the shadow position at certain times of a day, we can easily create ‚sundial‛ We can find the location of the sunrise-sunset by measuring the Azimuth when the altitude of the sun is 0 degrees (while the sun is existing at the horizon either in the east or in the west) at certain days-months of the year since the sun moves along ‚Ecliptic‛, if we do have a measurement that

329 can measure it accurately, we can measure the position of the sunrise-sunset differently everyday, around 15 libda a day. After the sun having risen, the altitude of the sun will gradually increase until reaching the highest point and slightly decrease. The azimuth will change its value every time measured. This means that the sun changes its position all the time as shown in the table below. Table1: The azimuth of the sun while it is rising and setting, and the highest altitude of the sun measured in Bangkok on the days-in the months in a years. Day-Month Azimuth Altitude Season Rising Falling 76 Summer 270 90 21 March 90 284 84 Rainy 27 April 76 290 81 season 20 May 70 293 83 Winter 22 June 67 291 90 20 July 69 284 76 16 August 76 270 66 23 September 90 260 56 20 October 100 250 52 247 56 20 November 110 250 67 22 December 113 259 20 January 110 20 February 101 From the information in table1-1, write a sphere model of the sky and identify the direction of North-South, East-West. Then write the sun’s passage from Azinuth’s value of its rising and falling including the highest uprisen angle of each day.

330 เหนอื ศีรษะ มมุ เงย ตะวันตก ใต้ เหนือ ตะวนั ออก มุมทศิ ใต้เทา้ Picture 5: The sphere model of the sky with the sky edge line to divide the circular model indicating the star position. The sky edge lene is compound to Azimuth and Altitude angles. Constellations and seasons In the ancient times, human beings cound observe the positions of sunrise and sunset and the existing constellations, which are related to season’s change causing human beings to live happily and normally. From observing the sun and the constellations existing in the sky after the sun set, human beings knew when to plant, when to harvest and when to collect dry food for the winter season. They began to have the materials in the sky to indicate time especially when they have changed their ways of primitive life to more developed living, most of which are emphasized on farming or agriculture; they have to conceive of the changes in nature. We may observe or experiment to study the rising and setting and the positions of the sun and the apparent the constellation at any day in a year when the earth orbits round the sun in one circle. People on earth can see the sun pass twelve groups of fixed stars. On average, it takes one month for the sun

331 Picture 6: 12 groups of Zodiacal stars and the position of the earth while the sun is passing through them In the Zodiac there are fixed stars that the sun passes through; for example, the sun passes a group of fish stars (Pisces) during March12-April20. March means ‚arrival‛; therefore, it is the duration of time when the sun is in this group of stars. Picture7 Groups of fixed stars in the Zodiac and the position of the sun existing among the groups of stars (seen from the earth)

332 The position of the sun in the Zodiac will be in consistent with the manes of the twelve months named by the Thai in the reign of King Rama II; for example, the sun will be seen in a groups of the stars called ‚The Seales‛ during a month of October and during this month, other groups of stars will be existing after the sunset early at night which consist of the scorpion, the archer, the seagoat, the water carrier, the fish and the ram respectively from the west to the east. Therefore, the position of sunrise and sunset in a group round, seasons, and groups of stars that appear in the sky are all related. Topic 2: Observation of the position of fixed stars In ancient times, people believed that all the stars in the sky are at the same distance from the earth; those stars were fixed on abig sphere called ‚Celestial sphere‛, having the earth at the center of the sphere. The celestial sphere orbits round the earth from east to west, but the earth stays still without movement. Later, the experts studied more astronomy and found that the stars in the sky are not at the same distance from the earth. Daytime and nighttime were caused from the earth’s rotation not from the spin of celestial sphere as believed in the past. However, nowadays, astronomers still identify the position of the stars from celestial sphere. The reason for this is that if we assume that the earth is the center with the celestial sphere moving around it, it will be easier to identify the position or compare the positions of the material in the sky and easily observe the movement of those materials. Space Imagination  If the axis of the earth is extended out on both sides in the sky, we can get two imaginary points called ‚North celestial pole‛ and ‚South celestial pole‛. Both of poles are on the same axis as the earth moves round itself. The north celestial pole will point to the position of the North Star; this can make us see that there is no movement of the North Star.

333  If we extend the earth equator around the sky, we can get an imaginary line called ‚Celestial equato‛, which divide the sky into two parts: ‚Northern hemisphere‛ and ‚Southern hemisphere‛ like the earth equator dividing the earth into northern part and southern part. Picture8: Celestial sphere Picture 9: Celestial Sphere Imagination from the earth  In fact, we cannot see all celestial since we are on the earth surface; we can see only half of it and call the edge line at the earth surface ‚Horizon‛ which is like a perimeter on a flat area where we are the center of it.  If a line is drawn from the north to the south passing the point above the head, we will get an imaginary line called ‚Meridian‛  If a line is drawn to cannot the east and the west having it in the right angle with the earth exis all the time, we can get ‚Celestial equator‛ which divides the sky into the northern hemisphere and the southern hemisphere. If we obseve it from Thailand, which is located in the northern hemisphere, we can always see the area in the northern hemisphere is larger than that in the southern hemisphere.

334 The movement of celestial sphere When we look at the sky from the earth surface, we can see the celestial sphere move from the east to the west. However, since the earth is round, the place as the angle where we watch the movement of the celestial sphere depending on the latitude where the observer is; for examples,  If the observer is at the equator or at latitude 0 degree, the north celestial pole will be exactly at the north horizon (picture 10)  If the observer is at higher latitude like at latitude 13 degrees, the north celestial pole will be 13 degree higher from the north horizon 13 degree (picture 11)  If the observer is at the north pole or at latitude 90 degrees, the north celestial pole will be 90 degree higher from the horizon (picture 12) We can conclude that which attitude the observer is, the north celestial pole will be at the same latitude higher from the horizon. Picture 10: Latitude 0 degree N The observer is at equator (latitude 0 degree); the North Star will be exactly at the horizon. The stars rise or set at the angle of 90 degrees to the horizon. Picture 11: Latitude 13 degree N The observer is in Bangkok (latitude 13 degrees N); the North Star will be 13 degrees above the north horizon. The stars rise or set 13 degrees including towards the south.

335 Picture 12: Latitude 90 degree W The observer is at the North Pole (latitude 90 degrees N); the North Star will be 90 degrees above the horizon and the stars move parallelly to the earth surface. Angular distance In measuring the distance between the stars and the celestial sphere, we cannot directly measure in meters or kilometers because the distance between the stars is bending so it has to be measured in angular distance; for example, we may say star A is 5 degrees from star B or we can say that the moon is ½ degrees in size. All must be measured is in angular distance. Picture 13: showing angular distance between star A and star B which is equal to the angle between the two lines drawn from the eye to star A and star B. The angular distance measured is the distance that can be seen, but; in fact, star A and star B may have different distance from us or they may have the same distance because we can see only 2 dimensions of them; we cannot observe the deep dimension.

336 How to easily measure the angular distance In measuring angular distance, if we need the correct and exact answer, complicated equipment is needed. However, we can approximately measure the angular distance be using our hands and fingers; for example, if we spread our hand and stretch the thumb out the little fingers and the arm. The width between the two fingers compared to the angle in the sky which is about 18 degrees. If the two stars are in the same distance as this width, it means that their angular distance is 18 degrees too. Picture 14: To measure the angle by hands On the night of full moon, try clenching a list and raising the little finger, and stretching the arm, then lay the finger flat against the moon; we can see that our little finger will exactly be in the line of sight of the moon. Therefore, we may say that the moon has ½ degree angular diameter; the angular diameter is the angular distance measured between the edge line of the moon. The angular diameter of material depends on the distance of the material and the observer as well as the real diameter of the material Picture 15: Angular sizes

337 Example: Imagine a ball is placed 1 meter away from us. Try measuring its angular diameter and move the ball away these times in distance. The angular diameter will decrease one- third of what was measured before. Therefore, ‚angular diameter value‛ is the ratio of the real material to the distance of it. Constellations Although, there are 88 groups of stars in the sky only 12 groups are in the Zodiac including some bright stars. These groups of stars cannot be seen all the time because the earth moves round itself and orbits round the sun. Each group of bright stars cannot be seen when they rise and set at the same time as the sun. Brightly fixed stars around ‚Ursa Major‛ Leo Regulus Virgo Ursa Major Spica Polaris/North star Areturus Ursa Minor Bootes Picture 16 Brightly fixed stars around ‚Ursa Major‛ When starting to look at the stars, we have to find out the position of brightly fixed stars first to see the shapes of them, we have to locate the North direction and observe the movement of groups of stars from the east to the west due to the earth’s movement around itself. ‚Ursa Major‛ is composed of seven bright stars arranged in a large Dipper shape; the first two stars are called ‚The Pointer‛ by the European meaning of the arrow is pointing towards ‚The North Star/Polaris‛ all the time. Polaris’ distance from the first two stars is five times angular

338 distance of the angular distance between the two stars. Polaris is at the tail of ‚Ursa Minor‛ which consists of dim stars arranged in a small dipper shape. Although, Polaris is not too bright, there are no other stars than it, so Polaris is rather noticeable. When we know the location of Polaris, we will know the movement direction of the sphere. If we face the North Star, on the right is the east and on the left is the west. All groups of stars will move to the right, highest to the North and set to the left. We can start from ‚Ursa Major‛ by drawing a curved line along ‚The tail of the bear‛ or the dipper’s handle to ‚Arcturus‛ or ‚Dao yod maha chulamanee‛ which is a brightly orange star in ‚Bootes‛ and draw the curved line twice as long, we can see a brightly white star called ‚spica‛ in the virgo groups of stars in which there are 7 stars arranged in Y shape on ecliptic line. The fourth and the third stars are at the dipper pointing to ‚Regulus‛ in ‚heo‛. Groups of Zodiac stars are always on eliptic line. If we have found one group of Zodiac stars, we can look for other groups of Zodiac stars which are next to them such as in picture 16; we can see group of ‚Leo‛ and a group of ‚Virgo‛. Afterwards, we can estimate the positions of ‚Cancer‛ and ‚Libra‛. Winter Triangle Orion Rigel Betelgeuse Canis Sirius Canis Major Minor Procyon East Picture 17: Winter Triangle Early at night in winter, there are groups of bright stars in the east which are Orion, Canis Major, and Canis Minor. If drawing a line connected Betelgeuse (the bright red stars) at the

339 shoulders of Orion to Sirius (the brightest white stars) at the head of Canis Major and Procyon (the bright white stars) at the head of Canis Minor, we will get a triangle called ‚Winter Triangle‛ which rise early at night in winter. When we start to practice studying the stars in the sky, the groups of stars called ‚Orion‛ should be studied first since they are composed of bright stars with significant patten easy to remember and rise early at night in winter; they are called winter stars in which there is good atmosphere without any clouds in the sky. The unique characteristic of ‚Orion‛ is there are 3 bright stars arranged in a straight line called ‚Orion’s belt‛ locating within 4 stars. At the south of these stars, there are 3 tiny stars arranged like ‚the handle of the plough‛ for the Thai people, but the European call them ‚Orion’s sword‛. Around ‚Orion’s sword‛, if we look through a telescope, we will see ‚Nebula M42‛ which is a group of gas in the space’gathering itself to be a new star in the middle and shines to Nebula making us see it. The two bright stars around the shoulders of ‚Orion‛ in the east and at the knee in the west are different in colours. Betelgeuse is red, but Rigel is blue. The colour of the star tells the age and the temperature of the star; blue star are young with the temperature of 10,000-20,000 Kelvin and red star are old with lower temperature of 3,000 Kelvin. The sun is yellow; it is middle-aged with the surface temperature of 5,800 Kelvin. In Canis Major, there is the most brightly fixed star called ‚Sirius‛ and ‚a robber star‛ for the Thais (since it is so bright that a robber sees the way and robs people). Sirius is not a big star, but its distance is only 8.6 light years from the earth; the Rigel in Orion is brighter than Sirius, but its distance from the earth is 777 light years. Therefore, seen from the earth, Rigel is less bright than Sirius.

Summer Triangle 340 Aquila Deneb Vega West Picture 18: Summer Triangle Early at night in the Lyra winter, there are groups of stars in the west such as Lyra, Cygnus, and Aquila. If we draw a line connecting Vega (the bright star in Lyra) to Deneb (the bright white star in Cygnus) and Altair (the bright star in Aguila), we will get a sealene triangle called ‚summer triangle‛ which is opposite to winter triangle. While summer triangle stars are setting, winter triangle stars are rising. Summer triangle rise early at night of the summer in Europe and America which is the rainny season in Thailand. In crescent moon night without being disturbed from the moonlight. If we notice it carefully, we will see a bright sky stripe like white clouds lying across the sky, passing Aquila, Deneb to Cassiopia. The bright sky stripe is ‚The Milky Way‛.

341 Topic 3: How to find out Polaris (The North Star) Finding it from ‚Ursa Major‛ Ursa Major Polaris Ursa Minor North Picture 19: How to find out Polaris from ‚Ursa Major‛ Sometimes, we can find the North Star/ Polaris from watching Ursa Major or called groups of crocodile stars which are seren bright stars arranged in a dipper shape. The first two stars of a dipper will always point to Polaris where the sphere mores, the distance of Polaris will be 5 times away from the first two stars as shown in picture 19 Finding it from Cassiopeiae Cassiopia Polaris Ursa Minor North Ursa Major Picture 20: Rising-Setting of the stars around the north sky In some nights, when Ursa Major have just set or have not risen, we can estimately find the north from Cassiopeiae which is composed of 5 bright stars arranged in forms of ‚M‛ or the

342 upside down ‚W‛. Cassiopeiae will always be opposite to Ursa Major. Therefore, while Ursa Major is setting, Cassiopeiae is rising as shown in picture 20 Point to Polaris Orion Betelgeuse East Picture 21: Orion always faces towards Polaris Sometimes when the clouds cover the sky in the north, we cannot see Ursa Major or Cassiopeiae. In this case, we head to Polaris (the North Star). Besides Orion will turn its at celestial equator which mean Orion will always rise-set in the east and the west. Topic 4: Starmap If we can read the map of the stars, we can correctly look at any stars at any time in the sky. Before reading the starmap to compare with the existing stars in the sky, the observer must know the directions: North-South-East-West. -Try estimating Altitude and Azimuth of the North Star. -Whether or not we know that we can find Polaris from Ursa Major or Cassiopia. The popular starmap used at present is a moring starmap with 2 pieces of hard paper fixed together in the center; one piece is a picture of groups of stars and bright stars written within the circle. At the edge of the circle, days and months are identified around it. The piece of paper on the top shows the time around it. To use the starmap, we only move the botton piece of paper with day and month to the point showing the time needed to know. From the top piece of paper, the groups of stars exist on the starmap are the stars in the sky at the real time as shown in picture 22

343 Picture 22: Moving starmap If is used at the observation place, we have to turn our face to the north and lift the map above the head, having the direction of the map point to the real direction by moving days-months to the time observed and do the following exercise. 1. In the starmap, is there anything telling the locations of the moon and other planets, why? 2. Observe existing groups of stars in the sky from the starmap and identify the groups of stars seen in the east, west, and middle of the head and also find out what groups of stars in the Zodiac exist in the sky at that time. Topic 5: How to get benefits from fixed stars Human beings made use of watching the stars in former times and have still done until the present time. Although, nowadays, modern technology can compensate it and observing the stars in the sky is less important. However, there are a lot of myteries concerning the stars to study especially high technology which helps human beings continually study the stars. Therefore, the stars will still be useful for human beings for a long time since in the space is like a natural laboratory which cannot be made, so the study of the stars can help us more understand the earth and ourselves. Although, people in general make less use of the stars, there are still many groups attempt to make use of natural equipment given from nature, and there is no need to pay a lot of money. The examples are as follows.

344 Way of living The groups of people using the stars for their careers are farmers, fishermen, and hiker. The farmers observe the stars to choose the right seasons for their plantations. In former times, the Thai people watched the stars to perdict the amount of rainfalls or other phenomena. Nowadays, farmers, fishermen, and hiker observe the stars to lead their ways or calculate approximate time at night or their locations on earth. Education In the ancient times, people were often frightened when there were astronomical phenomena such as solar eclipse, lunar eclipse, or comets in the sky since they did not understand the cause of them. Nowadays, we are not frightened any longer resulting from studying astronomy which can help us know and understand the nature more. The more we know about it, the more supecious we become. Therefore, the study of astronomy can answer all of the questions. Many types of technology used for studying stars have been developed for our ways of living such as Remote Sensing taking pictures by CCD system. Astronomy not only helps us understand the nature, but it also helps us live happily with the nature.

345 Exercise Make X in front of the right answer 1. What is the length of the line of the sun path passing each group of stars in the Zodiac? a. 10 degrees c. 20 degrees b. 30 degrees d. 40 degrees 2. Why can we see the sun move past groups of Zodiac stars? a. The sun orbits round the earth. b. The earth orbits round the sun. c. The earth moves round itself. d. The groups of Zodiac stars orbit round the sun. 3. Which groups of Zodiac stars have rising and setting path to the south most? a. The Archer (Sagittarius) c. The Fish (Pisces) b. The Virgin (Virgo) d. The Twins (Gemini) 4. Which groups of Zodiac stars have rising and setting path to the north most? a. The Archer (Sagittarius) c. The Fish (Pisces) b. The Virgin (Virgo) d. The Twins (Gemini) 5. Which groups of Zodiac stars rise and set in the east and in the west? a. The Fish (Pisces) and The Virgin (Virgo) b. The Archer (Sagittarius) and The Twins (Gemini) c. The Crab (Cancer) and The Goat (Capricorn) d. The Lion (Leo) and The Water Carrier (Aquarius) 6. How many degrees will the sun change its position in the sky compared with the fixed stars? a. 1 degrees c. 10 degrees b. 20 degrees d. 30 degrees

346 7. Why can we see the stars rise and set? a. The sun orbits round the earth. b. The earth orbits round the sun. c. The earth moves round itself. d. The stars orbit round the earth 8. Which groups of Zodiac stars can we see at the celestial line in the east at 9 p.m. on September 3? a. Sagittarius c. Capricorn b. Canis major d. Pisces 9. Which groups of the stars can be seen all night in summer? a. Orion c.Canis major b. Canis minor d. Cygnus 10. Which groups of stars are not in ‚Winter Triangle‛? a. Orion c.Canis major b. Canis minor d. Cygnus 11. Which groups of the stars rise in the east early at night in winter? a. Orion c.Lyra b. Aquila d. Cygnus 12. Which stars does not exist in the starmap? a. Aquila c.Mercury b. Spica d. Arcturus 13. What is the thick line in the starmap drawn from the east to the sky and to the west called? a. Ecliptic c. Horizon b. Celestial equator d. Meridian

347 14. What do we call the dotted line drawn from the east to the sky to the west? a. Ecliptic c. Horizon b. Celestial equator d. Meridian 15. Which star can we find if we draw a straight line along Orion’s belt to the south (one the left of Orion)? a. Altair c. Aldebaran b. Castor d. Sirius 16. If we see Orion in the sky, which part of Orion is Polaris located? a. Orion’s belt c. Orion’s leg b. Orion’s shoulders d. Orion’s head 17. Which groups of stars help us easily find Polaris? a. Orion c. Ursa Major b. Cassiopeiae d. Both b and c 18. If we watch the stars in Bangkok, how many degrees Polaris (the North Star) are above the celestial line of the sky? a. 12 degrees c. 13 degrees b. 14 degrees d. 15 degrees 19. If we watch the stars in Chiengmai, how many degrees Polaris is above the celestial line of the sky? a. 16 degrees c. 17 degrees b. 18 degrees d. 19 degrees 20. If the students are tralling in the sea and see Polaris is 15 degrees above the celestial line, which statement is true? a. The students are at latitude of 15 northern degrees. b. The students are at latitude of 15 southern degrees. c. The students are at longtitude of 15 eastern degrees. d. The students are at longtitude of 15 western degrees.

348 Key to exercise 1. b. 2. b. 3. a. 4. d. 5. a. 6. a. 7. c. 8. d. 9. d. 10. d. 11. a. 12. c. 13. b. 14. a. 15. d. 16. d. 17. d. 18. c. 19. b. 20. a.

349 Lesson 14 Electricians Essence Choosing a career to be an electrician is one of the interesting and high-paying jobs. There are several different types of electrician specializations and different responsibilities and duties to perform. The electrician working on the large construction will use specific tools and specialized skills which are different from the electrician working in industries. Basically, electricians must have basic electrical knowledge, can work with blueprints, and repair electrical appliances as well. At present, electricians may be employed by electrical contractors or work in the large industries. Furthermore, many of electricians are self-employed or contractors themselves. In addition, some of them work for government organizations or businesses which provide services to their own agencies. Although jobs for electricians are found in all parts of the country, most of them have to work in industrial or developing areas. Expectation Learning Outcomes Explain, design, plan, experiment, test, and perform on the power correctly and safely. Analyze and compare the advantages and disadvantages of series, parallel, and combination circuits. Apply the electrical knowledge and skills properly to the management and services. Scope of Content 1. Types of electricity 2. Tools for electricians 3. Electrical circuit tools 4. Connected simple circuits 5. Ohm’s law 6. Simple wire up 7. Use of electrical appliances 8. Safety and accidents of jobs for electricians 9. Management and Services 10. Science project to careers 11. Electricity vocabularies

350 1. Types of electricity are classified into 2 types as follows; 1.1 Static electricity is an imbalance of electric charges within the surface of a material. A static electric charge is created whenever two surfaces contact, for example, when amber gives up electrons to wool, it will become negatively charged and the wool has positive charge. 1.2 Electric current is a flow of electrons from an electric source through a conductor from one place to another, which is produced by forces; heat, light, chemical reactions, and electromagnetic power. The electric currents are divided into 2 types as follows; 1. Direct current (DC) is an electric charge always flowing in constant directions and magnitudes. The common sources producing DC are batteries, dry cells. In order to convert the currents to DC, you need to use an adapter. 2. Alternating current (AC) is the flow of electric charge periodically reverses directions and magnitudes. AC is commonly used in homes such as lighting systems, radios, televisions, and fans etc.