I find it simple when we have our reporting in Physics about Light as Wave because I already encounter this topic before with Ms. Gadingan, when I was still in 3rd year. I already have an idea what is the definition of wave, its characteristics, and its properties.
I have already known that wave is everywhere. We encounter them every day. I am also familiar with its terms which are sound waves, light waves, radio waves, water waves, and even simple waves on string. Because of the discussions, at this moment, I have an idea that the sound waves travel through the air to your ears. They make your eardrum and the inside of your ears vibrate. Your ears send a signal to your brain. Your brain tells you that you are hearing a guitar string. You cannot see sound waves, but you can see water waves. If you drop a pebble in a still pond or a big tub of water, the pebble will make waves. You will see the waves go outward through the water in circles. Sound moves through the air in similar waves. Radio waves are invisible. You cannot see or feel them. You can only hear radio waves if you turn on a radio. Radios turn radio waves into sound. Light Wave, light conveyed by wave motion rather than as a stream of particles. And also, I know how to distinguish crest and trough. The highest point of the wave which is called its crest and the lowest point is the trough. Amplitude is the displacement from the resting position to the highest or lowest point of the wave.
The distance from one point to the next identical point of the wave is called Wavelength. The characteristics of a wave are frequency that describes how often a vibration occurs; period is the time needed to complete one vibration; and wave speed is the rate at which the wave travels through a particular point. It is related to the wave’s frequency and wavelength. Vibration refers to one complete up-and-down motion of the rope. The SI unit of frequency is the herthz and abbreviated by Hz. It is equivalent to one cycle per second. One vibration per second is equal to one Hz. Higher period, shorter wavelength also, higher wavelength, lower frequency. One thing I’m sure of, you can always get the time if there’s frequency. And you can always get the frequency if there is time. Because of the previous discussion, at this instant I can differentiate transverse waves from longitudinal waves. In transverse waves, the vibrational direction of the particles in the medium is up and down perpendicular to the direction of the wave while in longitudinal waves, the vibrational direction of the particles of the medium is parallel to the direction of the wave.
As well, I learned that the properties of a wave are reflection, refraction, diffraction and interference. The law of reflection allows us to figure out in advance how our image would appear in a mirror. The angle of incident light is always equal to the angle of reflection. The intersection of any two reflected rays is the point where the image can be found. There are two kinds of images and this are virtual images which cannot be projected onto a screen and real images which can be projected onto screen. I have learned that the image formation depends on what kind of mirror you are using. I know two kinds of mirrors and this are plane mirrors and curve mirrors. In plane mirrors, the image appears the same size as the object. When the mirror is curved, the sizes of the object and the image as well as their distances from the mirror are no longer of equal measure. The parts of the curved mirror are vertex, focal point, center of curvature and focal length. Vertex describes as the physical center of the mirror and has the V symbol. Focal point has the symbol F it is the midpoint of the line between the vertex and the center of curvature. Center of curvature is the geometrical center of the curved mirror and it has C symbol.
Focal length which has the symbol f is the distance between the focal point and the vertex. The vertex, the focal point, and the center of curvature all lie along the principal axis, also called the optical axis. The relation between the focal length and radius of curvature of a mirror is f= R/2. Curved or spherical mirrors are classified as concave or convex. A concave mirror has a reflecting surface that is curved inward and it’s a diverging mirror. While that of a convex mirror is curved outward it is also a converging mirror. When Ms. Uy let us see the different kinds of mirror, I can really identify which of those mirrors are concave and convex mirrors. When I try it on, I can really see the difference of each mirror. While we have our activity entitled Mirror, Mirror on the wall and what you see is not what you get, I was amazed and excited of what will happen on our activity. Wow is only just an expression I said while we do the “Mirror, mirror on the wall” activity.
I can clearly see the reflected objects in the illustration board. Because of the mirror we use and because of the light from the sun. The same as the “What you see is not what you get” activity, I can clearly see the reflected candle in the illustration board. The closer the mirror to the candle, the clearer and bigger the reflected candle can be seen in the illustration board. The far the mirror to the candle, the light of the candle can’t be seen to the illustration board. The second property of wave is refraction. It is a change in speed and direction of a wave as it travels from one medium to another. Because of our activity in physics entitled magic pencil, I clearly understand the meaning of refraction. When I do the activity, when I dip the pencil into a glass of water, the pencil looks bent. When I look at the part of the pencil from different positions, from above, from the side of the glass, and below, the pencil really looks bigger. Then I realize that these effects are all caused by refraction- the bending of light as it passes from one medium to another. The third property of wave is diffraction. Diffraction is the bending of a light wave as it passes through a narrow opening forming semicircular light waves. It occurs to some degree in all openings. The amount of diffraction depends on the same size of the wavelength and the obstruction (opening or slit). Sometimes, the diffraction becomes too fine to be visible to the naked eye. The last property of wave is interference. The principle behind the hologram is a phenomenon called interference. A hologram is a three-dimensional version of the familiar two-dimensional photograph.
Because of our reporting, group activities and quizzes, I learned many things all about waves. I gather more information about waves. And also, because of this topic, I learned new things which I don’t encounter before. I am more knowledgeable now compared before.
Light and Vision When Ms. Uy discussed the topic, I already know that optics is the science dealing with the generation and propagation of light, and the changes that it undergoes. This topic focuses on how the properties of light, such as refraction and reflection, enable our eye to form images.
Because of our discussions, I know the structure of the human eye. And these are sclera, cornea, choroid, blood vessels, ciliary muscles, iris, suspensory ligaments, pupil, retina, optic nerve, aqueous humor, vitreous humor, lens and fovea centralis. The outermost layer of the eye is called the sclera. Attached to the sclera are the muscles that move the eye and maintain the shape of the eye. Light enters the front part of the sclera, the cornea. The cornea is tough and clear. The next layer is the choroid. The choroid contains the blood vessels, the ciliary muscles and the iris. The ciliary muscles control the size of the lens for focusing. These muscles are attached to the lens via the suspensory ligaments. The iris is the colored part of the eye. It is made up of muscles that control the size of an opening called the pupil. The innermost layer of the eye is the retina. It contains light-and color-sensitive cells, the rods and cones. The retina also contains rhodopsin a chemical that converts light into electrical impulses. The optic nerve conducts these electrical impulses to the brain where they are interpreted. The eyeball has two sections filled with fluid, the aqueous humor and vitreous humor.
These sections are separated by a clear, biconvex structure called the lens. Fovea centralis is a region in the retina. I have learned that for a person to see, the cornea and the lens should refract light and produce an image in the retina discernible by the brain. Accommodation is the ability of the eye to adjust its focal length. Because of our discussions, I learned that during accommodation, the shape of the lens changed from moderately convex to highly convex. How does the eye change the shape of its lens? How about when the eye is focusing on distant object? For the reason that I listen to Ms. Uy while she’s discussing, I am able to answer these two questions. When the eye focuses an image or a nearby object, the focal length become longer and the image is focused behind the retinal surface. The eye accommodates by assuming a lens shape that has a shorter focal length. For the second question my answer goes this way. A normal-shaped lens focuses distant objects at a point in front of the retina. The eye accommodates by assuming a lens shape that has a longer focal length. This condition is known as presbyopia. There are also common eye defects. One of the common eye defects is hyperopia or farsightedness. This condition is due to either an eyeball that is too short or, sometimes, a lens that is too weak.
Another common eye defect is myopia or nearsightedness. In myopia, the ciliary muscle is completely relaxed and the light rays coming from distant objects are focused in front of the retina. Astigmatism, another common eye defect, is caused by an irregular curved cornea that distorts the focus of light entering the eye. There are some ways in correcting common eye defects. Eye defects can be corrected using eyeglasses or contact lenses of different shapes. In hyperopia, his abnormal condition can be corrected by adding refractive power with a convex lens in front of the eye. In myopia, this eye defect can be corrected by placing a diverging lens in front of the eye. The usual procedure to correct the astigmatism is to find a spherical lens by trial and error that corrects the focus in one of the two planes of the astigmatic lens of the eye. Knowing the common eye defects makes me think that I’m very grateful to have eyes which works normally and have no any defect.
“Did you know that the eye is optically equivalent to the camera?” a question asked by Ms. Uy. As I hear the question asked by Ms. Uy, I don’t have any idea. I don’t know that the eye is optically equivalent to the camera. Then as the discussion goes on, I found out that the eye is optically equivalent to the camera. The eye has a pupil which is the opening and the camera also have an aperture which is the opening. Image formed from the retina of the eye that is equivalent to the sensor/film of the camera. The eyelids of the eye are equivalent to the shutter of the camera. Both regulate the light that will enter. Eye accommodates and also camera focuses. There are many other optical instruments like the telescope and light microscope. Telescope is an instrument that makes distant objects look closer. There are two types of telescope and these are refracting telescope and the reflecting telescope. Refracting telescopes have a high resolution. Also, refracting telescopes are expensive because of the high cost of making the aperture. The reflecting telescope uses mirrors instead of lenses to gather and focus light. The other optical instrument is the light microscope which works the same way as refracting telescope. Unlike the telescope, however, the microscope does not need large objective lenses. In our biology class, I have learned that the light microscope has two objectives- the low-power objective and the high-power objective. The low-power objective has a lower magnification because the lens is relatively flat. The high-power objective has a higher magnification because the lens is rounder. Modern microscopes have very powerful objective lenses that can magnify images up to a thousand times bigger than the original.
Just after listening to the report, I realized that as a person grows older, the lens grows larger and thicker and become less elastic. Therefore, as you grow older, your ability for accommodation decreases. The lens is almost nonaccommodating. In addition there are many other optical instruments. I can’t believe that eye is optically equivalent to the camera. Thanks to Ms. Uy I truly understand the topic well. And because of our quizzes and summative tests, the information store up inside my mind. COLOR ADDITION and Types of Scattering of Light
There are also types of scattering light. In Rayleigh scattering, scattering particles are small compared to the wavelength of light. In Mei scattering, particles are of same size as the wavelength of light. It includes dust. In Non-selective scattering, particles are much bigger than the wavelength.
When Ms. Uy discussed about Color Addition and Color Subtraction, I got surprised. I can’t imagine it, because I thought only mathematics subject needs a solution. Also in color addition and color subtraction. First, I got confused but when Ms. Uy showed us the color pyramid, I found it simple. Because of the discussion I have learned that red, green and blue are the primary colors. And the primary pigments are cyan, magenta and yellow. As far as I could remember, this topic is the one of easiest topic ever. I really love adding and subtracting colors. Because of Ms. Uy, I have now the idea what’s the result if I add and subtract colors.
2nd Grading Radiation and Life This topic is uncomplicated for me because I already have an idea that radiation is energy traveling through space. And one of the most familiar forms of it is sunshine. I really understand this topic because sunshine is also part of our life and it delivers light, heat and suntans. We can control the effect on us with sunglasses, shades, air conditioners, hats, clothes and sunscreen which are common things into people nowadays. The kinds of radiations are ionizing radiation, background radiation, cosmic radiation and terrestrial radiation. Ionizing radiation can cause damage to matter, particularly living tissue. At high level it is therefore dangerous, so it is necessary to control our exposure to it. Background radiation is that which is naturally and inevitably present in our environment. People living or working at high altitudes receive more cosmic radiation. People living n granite areas or mineralized sands receive more terrestrial radiation. Because of this topic, I have an idea that radiation comes from atoms, the basic building blocks of matter. Most atoms are stable, bit certain atoms eventually disintegrate into a totally new atom.
These atoms are said to ‘radioactive’ or ‘unstable’. The nucleus can undergo a spontaneous change towards a stable form. This is called ‘radioactive decay’. The amount of radioactive material is given in Becquerel (Bq) a measure which enables us to compare the typical radioactivity of some natural and other materials. The half-life is the time taken for half of the atoms of a radioactive substance to decay. Ms. Uy gave us the formula in finding the half life of some materials then I tried to solve it using the formula. It is very simple, because you’re just going to substitute the given to the formula then solve. Father of nuclear physics.