Wednesday, March 5, 2008
3/5/08 scribe thingy
So today we took a lot of notes….
Today started off somewhat exciting with a four minute video about Benjamin Franklin. Nobody really understood what happened in the video because everyone was playing Frisbee, to be completely honest. We then talked about matter as a source of electricity. Matter is composed of atoms which are composed of neutrons (neutral charge), protons (positive charge), and electrons (negative charge). Neutrons and protons are located in the nucleus of an atom and the electron orbits the nucleus. We finished with matter and went into what a Coulomb is. This is a scalar quantity and 1 Coulomb = 6.25 x 10^18 elementary charges and one elementary charge = 1.60 x 10^-19 C. After that, we figured out the reasoning behind how an object becomes positively or negatively charged. This happens when there is either an excess or a deficiency of electrons. The way an object becomes electrically charged is by gaining or losing electrons which all depends on the tendency of the material. We also did a demo on how to attract a neutral object. Mr. Wirth showed it was possible by rubbing a balloon on his head and then sticking it to the wall and showing us that it would stay where he left it. We then took a look at an electroscope. This is a device that determines the presence of an electrical charge and whether it’s positive or negative. Finally, we learned that there are ways to remove or add electrons to neutralize the static charge which is called grounding. Some examples of this are grounding straps and lightning rods. The End
Monday, March 3, 2008
Optical Fibers
Fiber optics are used to transport light and can allow for communications over long distances at much higher rates. Fibers are used in place of wire because they are not affected by electromagnetic forces.
Optical fibers work due to something known as total internal reflection, they more or less guide waves through the cable. There is a core and an outer layer that make up an optical fiber. The inner layer has a greater refractive index than the outer layer which causes light to reflect back into the inner layer. Due to the way the cables are designed they can not be easily connected in the way that wire can. They most be arched together perfectly in order to work properly.
Optical fibers have many uses in the world today. They are largely used in communications over long distances. This makes the use of repeaters unnecessary due to the fact that light travels through the cables without being lost. They each cable can also carry multiple wavelengths of light at the same time. These cables can save space and time because they can carry more in one cable than a number of other cables combined at much high speeds. They also make wire tapping extremely difficult due to the fact that they can not be easily joined with other cables. Because they are made out of glass or plastic they work by transporting light instead of electrical signals.
Another application for optical fibers is in sound. They can be used in SONAR and hydrophone systems quite easily due to the fact that they do not need electricity. They can also be used in temperature reading because they can operate at much higher temperatures.
Optical fibers are usually made of either glass or plastic. The glass fibers are generally made from silica or other materials depending on the wavelengths of the light that they will be transmitting. The glasses all generally have an index of refraction near 1.5. This gives the difference between the core and outer layer a difference of roughly one percent.
Optical fibers work due to something known as total internal reflection, they more or less guide waves through the cable. There is a core and an outer layer that make up an optical fiber. The inner layer has a greater refractive index than the outer layer which causes light to reflect back into the inner layer. Due to the way the cables are designed they can not be easily connected in the way that wire can. They most be arched together perfectly in order to work properly.
Optical fibers have many uses in the world today. They are largely used in communications over long distances. This makes the use of repeaters unnecessary due to the fact that light travels through the cables without being lost. They each cable can also carry multiple wavelengths of light at the same time. These cables can save space and time because they can carry more in one cable than a number of other cables combined at much high speeds. They also make wire tapping extremely difficult due to the fact that they can not be easily joined with other cables. Because they are made out of glass or plastic they work by transporting light instead of electrical signals.
Another application for optical fibers is in sound. They can be used in SONAR and hydrophone systems quite easily due to the fact that they do not need electricity. They can also be used in temperature reading because they can operate at much higher temperatures.
Optical fibers are usually made of either glass or plastic. The glass fibers are generally made from silica or other materials depending on the wavelengths of the light that they will be transmitting. The glasses all generally have an index of refraction near 1.5. This gives the difference between the core and outer layer a difference of roughly one percent.
The Human Eye
The human eye is a complex organ with a variety of layers and muscles. Obviously, it is used to help humans see. However, many humans experience vision problems that either impair their vision or prevent them from seeing altogether. Approximately 1 inch (2.54 cm) wide, 1 inch deep and 0.9 inches (2.3 cm) tall, the human eye is composed of fifteen main parts. Below is a detailed image of the eye:
Maintaining the shape of the eye is the tough, outermost layer the sclera. A clear layer, the cornea, covers the front of the sclera. Light first passes through the cornea when it enters the eye. Attached to the sclera are the extraocular muscles that move the eye. The choroid is the second layer of the eye. It contains the blood vessels that supply blood to all structures of the eye. The choroid is composed of the ciliary body and the iris. A muscular area that is attached to the lens, the ciliary body contracts and relaxes to control the size of the lens for focusing. Functioning to color the eye, the iris is an adjustable diaphragm surrounding the pupil. It has two muscles: the dilator and the sphincter. Both control the amount of light let into the eye by adjusting the pupil size. The color of the iris is determined by the color of the connective tissue and pigment cells. The innermost layer is the retina -- the light-sensing portion of the eye. It contains rod cells, which are responsible for vision in low light, and cone cells, which are responsible for color vision and detail. In the back of the eye, in the center of the retina, is the macula. In the center of the macula is an area called the fovea centralis. This area contains only cones and is responsible for seeing fine detail clearly. Inside the eyeball there are two fluid-filled sections separated by the lens, a clear structure used to fine-tune vision. The larger, back section contains a clear, gel-like material called vitreous humor. The smaller, front section contains a clear, watery material called aqueous humor. When drainage of the aqueous humor is blocked, a disease called glaucoma can result. The eye is unique in that it is able to move in many directions to maximize the field of vision, yet is protected from injury by a bony cavity called the orbital cavity. The eye is embedded in fat, which provides some cushioning. The eyelids protect the eye by blinking. Eyelashes and eyebrows protect the eye from particles that may injure it.
There are six muscles attached to the sclera that control the movements of the eye. They are shown here with their descriptions:
Muscle
Primary Function
Medial rectus
moves eye towards nose
Lateral rectus
moves eye away from nose
Superior rectus
raises eye
Inferior rectus
lowers eye
Superior oblique
rotates eye
Inferior oblique
rotates eye
After passing through the cornea, light passes through the aqueous humor, lens and vitreous humor. Ultimately it reaches the retina, which is the light-sensing structure of the eye. The retina is made up of cones and rods and is lined with black pigment called melanin to lessen the amount of reflection. The retina has a central area, called the macula that is responsible for sharp, detailed vision. The color-responsive chemicals in the cones are called cone pigments and are very similar to the chemicals in the rods. Each cone cell has a red-sensitive pigment, a green-sensitive pigment, and a blue-sensitive pigment. The presence of these pigments allow the eye to be sensitive to that color. The human eye can sense almost any gradation of color when red, green and blue are mixed.
In the diagram above, the wavelengths of the three types of cones (red, green and blue) are shown. The peak absorbency of blue-sensitive pigment is 445 nanometers, for green-sensitive pigment it is 535 nanometers, and for red-sensitive pigment it is 570 nanometers. Color blindness is the inability to differentiate between different colors. The most common type is red-green color blindness. This occurs in 8 percent of males and 0.4 percent of females. It occurs when either the red or green cones are not present or not functioning properly. People with this problem are not completely unable to see red or green, but often confuse the two colors. Another vision problem is vitamin A deficiency. When severe vitamin A deficiency is present, then night blindness occurs. This is when the levels of light-sensitive molecules are low due to vitamin A deficiency, there may not be enough light at night to permit vision. During daylight, there is enough light stimulation to produce vision despite low levels of retinal. Refraction is when light rays reach an angulated surface of a different material and the light rays bend. When light reaches a convex lens, the light rays bend toward the center:
When light rays reach a concave lens, the light rays bend away from the center:
Vision or visual acuity is tested by reading a Snellen eye chart at a distance of 20 feet. By looking at lots of people, eye doctors have decided what a "normal" human being should be able to see when standing 20 feet away from an eye chart. 20/20 vision means when standing 20 feet away from the chart you can see what a "normal" human being can see and have normal vision. If you have 20/40 vision, it means that when you stand 20 feet away from the chart you can only see what a normal human can see when standing 40 feet from the chart. 20/200 is the cutoff for legal blindness in the United States. It is also possible to have vision better than normal. A person with 20/10 vision can see at 20 feet what a normal person can see when standing 10 feet away from the chart. Hawks, owls and other birds of prey have much more acute vision than humans. A hawk has a much smaller eye than a human being but has lots of sensors (cones) packed into that space. This gives a hawk vision that is eight times more acute than a human's. A hawk might have 20/2 vision!
Normally, your eye can focus an image exactly on the retina:
Nearsightedness and farsightedness occur when the focusing is not perfect. When nearsightedness is present, a person can clearly see near objects, while experiencing difficulty seeing far objects. Light rays become focused in front of the retina. This is caused by an eyeball that is too long, or a lens system that has too much power to focus. Nearsightedness is corrected with a concave lens. This lens causes the light to diverge slightly before it reaches the eye, as seen here:
When farsightedness is present, a person can clearly see far objects, but has trouble seeing seeing near objects. Light rays become focused behind the retina. This is caused by an eyeball that is too short, or by a lens system that has too little focusing power. This is corrected with a convex lens, as seen here:
As stated earlier, to be legally blind visual acuity must be less than 20/200 with corrective lenses. Some causes of blindness include cataracts, glaucoma, macular degeneration, trauma, vitamin A deficiency, tumors, strokes, neurological diseases, hereditary diseases and toxins.
The human eye is an interesting organ full of potential complications and great physics lessons. With a complex anatomy and many ways to create problems, its no wonder so many people wear contacts.
Works Cited
Bianco, MD, Dr. Carl. "How Vision Works." How Stuff Works. 2008. 15 Feb 2008.
Maintaining the shape of the eye is the tough, outermost layer the sclera. A clear layer, the cornea, covers the front of the sclera. Light first passes through the cornea when it enters the eye. Attached to the sclera are the extraocular muscles that move the eye. The choroid is the second layer of the eye. It contains the blood vessels that supply blood to all structures of the eye. The choroid is composed of the ciliary body and the iris. A muscular area that is attached to the lens, the ciliary body contracts and relaxes to control the size of the lens for focusing. Functioning to color the eye, the iris is an adjustable diaphragm surrounding the pupil. It has two muscles: the dilator and the sphincter. Both control the amount of light let into the eye by adjusting the pupil size. The color of the iris is determined by the color of the connective tissue and pigment cells. The innermost layer is the retina -- the light-sensing portion of the eye. It contains rod cells, which are responsible for vision in low light, and cone cells, which are responsible for color vision and detail. In the back of the eye, in the center of the retina, is the macula. In the center of the macula is an area called the fovea centralis. This area contains only cones and is responsible for seeing fine detail clearly. Inside the eyeball there are two fluid-filled sections separated by the lens, a clear structure used to fine-tune vision. The larger, back section contains a clear, gel-like material called vitreous humor. The smaller, front section contains a clear, watery material called aqueous humor. When drainage of the aqueous humor is blocked, a disease called glaucoma can result. The eye is unique in that it is able to move in many directions to maximize the field of vision, yet is protected from injury by a bony cavity called the orbital cavity. The eye is embedded in fat, which provides some cushioning. The eyelids protect the eye by blinking. Eyelashes and eyebrows protect the eye from particles that may injure it.
There are six muscles attached to the sclera that control the movements of the eye. They are shown here with their descriptions:
Muscle
Primary Function
Medial rectus
moves eye towards nose
Lateral rectus
moves eye away from nose
Superior rectus
raises eye
Inferior rectus
lowers eye
Superior oblique
rotates eye
Inferior oblique
rotates eye
After passing through the cornea, light passes through the aqueous humor, lens and vitreous humor. Ultimately it reaches the retina, which is the light-sensing structure of the eye. The retina is made up of cones and rods and is lined with black pigment called melanin to lessen the amount of reflection. The retina has a central area, called the macula that is responsible for sharp, detailed vision. The color-responsive chemicals in the cones are called cone pigments and are very similar to the chemicals in the rods. Each cone cell has a red-sensitive pigment, a green-sensitive pigment, and a blue-sensitive pigment. The presence of these pigments allow the eye to be sensitive to that color. The human eye can sense almost any gradation of color when red, green and blue are mixed.
In the diagram above, the wavelengths of the three types of cones (red, green and blue) are shown. The peak absorbency of blue-sensitive pigment is 445 nanometers, for green-sensitive pigment it is 535 nanometers, and for red-sensitive pigment it is 570 nanometers. Color blindness is the inability to differentiate between different colors. The most common type is red-green color blindness. This occurs in 8 percent of males and 0.4 percent of females. It occurs when either the red or green cones are not present or not functioning properly. People with this problem are not completely unable to see red or green, but often confuse the two colors. Another vision problem is vitamin A deficiency. When severe vitamin A deficiency is present, then night blindness occurs. This is when the levels of light-sensitive molecules are low due to vitamin A deficiency, there may not be enough light at night to permit vision. During daylight, there is enough light stimulation to produce vision despite low levels of retinal. Refraction is when light rays reach an angulated surface of a different material and the light rays bend. When light reaches a convex lens, the light rays bend toward the center:
When light rays reach a concave lens, the light rays bend away from the center:
Vision or visual acuity is tested by reading a Snellen eye chart at a distance of 20 feet. By looking at lots of people, eye doctors have decided what a "normal" human being should be able to see when standing 20 feet away from an eye chart. 20/20 vision means when standing 20 feet away from the chart you can see what a "normal" human being can see and have normal vision. If you have 20/40 vision, it means that when you stand 20 feet away from the chart you can only see what a normal human can see when standing 40 feet from the chart. 20/200 is the cutoff for legal blindness in the United States. It is also possible to have vision better than normal. A person with 20/10 vision can see at 20 feet what a normal person can see when standing 10 feet away from the chart. Hawks, owls and other birds of prey have much more acute vision than humans. A hawk has a much smaller eye than a human being but has lots of sensors (cones) packed into that space. This gives a hawk vision that is eight times more acute than a human's. A hawk might have 20/2 vision!
Normally, your eye can focus an image exactly on the retina:
Nearsightedness and farsightedness occur when the focusing is not perfect. When nearsightedness is present, a person can clearly see near objects, while experiencing difficulty seeing far objects. Light rays become focused in front of the retina. This is caused by an eyeball that is too long, or a lens system that has too much power to focus. Nearsightedness is corrected with a concave lens. This lens causes the light to diverge slightly before it reaches the eye, as seen here:
When farsightedness is present, a person can clearly see far objects, but has trouble seeing seeing near objects. Light rays become focused behind the retina. This is caused by an eyeball that is too short, or by a lens system that has too little focusing power. This is corrected with a convex lens, as seen here:
As stated earlier, to be legally blind visual acuity must be less than 20/200 with corrective lenses. Some causes of blindness include cataracts, glaucoma, macular degeneration, trauma, vitamin A deficiency, tumors, strokes, neurological diseases, hereditary diseases and toxins.
The human eye is an interesting organ full of potential complications and great physics lessons. With a complex anatomy and many ways to create problems, its no wonder so many people wear contacts.
Works Cited
Bianco, MD, Dr. Carl. "How Vision Works." How Stuff Works. 2008. 15 Feb 2008
Sunday, March 2, 2008
Lucien's blog
Lucien Rouse
Mr. Wirth
Regents Physics
2 March 2, 2008
Light’s Behavior in the Sky
We all know that a beam of light is typically white. So why then, does the sky appear blue when there is only atmosphere between the sun and us, and, even more confusing, is why does the sky change colors during the sunset? How do rainbows materialize when the sun reappears after a shower? Lastly, what causes mirages, a trick of the mind, or something more realistic? Simple wave characteristics can be used to explain all of these phenomena.
When a child asks why the sky is blue, we typically answer that, “it just is.” What the child really should be told is that it is because of earth’s atmosphere. Earths atmosphere is made up of roughly seventy eight percent nitrogen, twenty one percent oxygen, and about one percent of other various gases; most prevalent among them is argon. Although the atmosphere seems invisible to the human eye, it actually absorbs about sixty percent of visible light. Here is where it gets back to the color of the sky. When solar radiation from the sun strikes the atmosphere, waves with a lower wavelength get absorbed. So particles in the atmosphere absorb the lower wavelength blue waves and the higher wavelength red waves pass through. The low wavelength waves are absorbed by the gas molecules in the atmosphere, then scattered. So the blue light is scattered, in all directions and whenever we look up, the sky appears blue. For the same reason, the horizon appears lighter. The blue light travels further, and passes through even more atmospheric particles, and is thus scattered ever more. Rayleigh scattering, as well as Mie Theory, explains the phenomena perfectly.
http://www.sciencemadesimple.com/sky_blue.html
At sunset, the sky appears red because the sun is almost tangent to the earth’s surface. Blue wavelengths are still scattered, but the light has to travel further to reach you, so even more of it is scattered, and only red light reaches you directly, so the sun appears less bright, and more red. The sky around it changes colors if there are a lot of water or dust particles in the air. They reflect the sun’s light in all different directions, and again, the blue light is scattered, so red light reaches the observer.
http://www.sciencemadesimple.com/sky_blue.html
The next question is about how rainbows are formed. The answer has to do with water particles in the air, and how light reacts to them. When white light hits a water particle, it is refracted and dispersed at entry, reflected by the back of the water particle, and refracted a second time when exiting. The result is that the different wavelengths of light are spread out, forming the red, orange, yellow, green, blue, indigo, and violet arc.
http://en.wikipedia.org/wiki/Rainbow
No matter what part of the rainbow you look at, that part of the rainbow is at forty-two degrees from your horizontal viewpoint and that part of the rainbow. This is because the light ray is refracted twice and reflected once, so the rainbow exits the droplet at a one hundred and thirty eight degree difference than it’s starting direction. One hundred and eighty minus one hundred and thirty eight equals forty-two, so the resulting rainbow that we see is always forty-two degrees off of lights direct path towards us.
The last question is about mirages. The typical thinking is that it is the delusional hallucination of dehydrated travelers, but in reality, anyone can see a mirage. Mirages occur when there is a severe difference in the temperature of different mediums that light pass through. For example, the ground near a road is often much warmer than the air above it. Light travels slower through warmer air, so, therefore, when light travels from cold air to warmer air, it will refract away from the temperature gradient. This is called an inferior image, and it is the type of mirage that makes the sky appear to be on the ground.
http://en.wikipedia.org/wiki/Mirage
By contrast, when light goes from hot air to cold air, a superior image is produced. These mirages are more complicated (they can be upside down or right side up) but they are basically the result of light being bent towards the temperature gradient, and then going through other stages. Superior images are only interesting because of the earth’s spherical shape, and they are what allow islands to appear closer to the shore than they really are. Mirages can only occur when the temperature difference is at least two degrees Celsius, but they are most clear with about a four and a half degree Celsius difference. Mirages are real enough even to be photographed.
Despite the common answers to these even more common questions, each of these phenomena is a result of light waves and the mediums that it travels through. It all has to do with wave characteristics, the very same ones that we are studying in Physics right now.
Work Cited
"About Rainbows." Aug. 2005. University Corperation for Atmospheric Reseach. 2 Mar. 2008.
"Why is the Sky Blue?" Science Made Symple. 1997. 2 Mar. 2008. Young, Andrew T. "An Introduction to Mirages." 1999. 2 Mar. 2008 .
Mr. Wirth
Regents Physics
2 March 2, 2008
Light’s Behavior in the Sky
We all know that a beam of light is typically white. So why then, does the sky appear blue when there is only atmosphere between the sun and us, and, even more confusing, is why does the sky change colors during the sunset? How do rainbows materialize when the sun reappears after a shower? Lastly, what causes mirages, a trick of the mind, or something more realistic? Simple wave characteristics can be used to explain all of these phenomena.
When a child asks why the sky is blue, we typically answer that, “it just is.” What the child really should be told is that it is because of earth’s atmosphere. Earths atmosphere is made up of roughly seventy eight percent nitrogen, twenty one percent oxygen, and about one percent of other various gases; most prevalent among them is argon. Although the atmosphere seems invisible to the human eye, it actually absorbs about sixty percent of visible light. Here is where it gets back to the color of the sky. When solar radiation from the sun strikes the atmosphere, waves with a lower wavelength get absorbed. So particles in the atmosphere absorb the lower wavelength blue waves and the higher wavelength red waves pass through. The low wavelength waves are absorbed by the gas molecules in the atmosphere, then scattered. So the blue light is scattered, in all directions and whenever we look up, the sky appears blue. For the same reason, the horizon appears lighter. The blue light travels further, and passes through even more atmospheric particles, and is thus scattered ever more. Rayleigh scattering, as well as Mie Theory, explains the phenomena perfectly.
http://www.sciencemadesimple.com/sky_blue.html
At sunset, the sky appears red because the sun is almost tangent to the earth’s surface. Blue wavelengths are still scattered, but the light has to travel further to reach you, so even more of it is scattered, and only red light reaches you directly, so the sun appears less bright, and more red. The sky around it changes colors if there are a lot of water or dust particles in the air. They reflect the sun’s light in all different directions, and again, the blue light is scattered, so red light reaches the observer.
http://www.sciencemadesimple.com/sky_blue.html
The next question is about how rainbows are formed. The answer has to do with water particles in the air, and how light reacts to them. When white light hits a water particle, it is refracted and dispersed at entry, reflected by the back of the water particle, and refracted a second time when exiting. The result is that the different wavelengths of light are spread out, forming the red, orange, yellow, green, blue, indigo, and violet arc.
http://en.wikipedia.org/wiki/Rainbow
No matter what part of the rainbow you look at, that part of the rainbow is at forty-two degrees from your horizontal viewpoint and that part of the rainbow. This is because the light ray is refracted twice and reflected once, so the rainbow exits the droplet at a one hundred and thirty eight degree difference than it’s starting direction. One hundred and eighty minus one hundred and thirty eight equals forty-two, so the resulting rainbow that we see is always forty-two degrees off of lights direct path towards us.
The last question is about mirages. The typical thinking is that it is the delusional hallucination of dehydrated travelers, but in reality, anyone can see a mirage. Mirages occur when there is a severe difference in the temperature of different mediums that light pass through. For example, the ground near a road is often much warmer than the air above it. Light travels slower through warmer air, so, therefore, when light travels from cold air to warmer air, it will refract away from the temperature gradient. This is called an inferior image, and it is the type of mirage that makes the sky appear to be on the ground.
http://en.wikipedia.org/wiki/Mirage
By contrast, when light goes from hot air to cold air, a superior image is produced. These mirages are more complicated (they can be upside down or right side up) but they are basically the result of light being bent towards the temperature gradient, and then going through other stages. Superior images are only interesting because of the earth’s spherical shape, and they are what allow islands to appear closer to the shore than they really are. Mirages can only occur when the temperature difference is at least two degrees Celsius, but they are most clear with about a four and a half degree Celsius difference. Mirages are real enough even to be photographed.
Despite the common answers to these even more common questions, each of these phenomena is a result of light waves and the mediums that it travels through. It all has to do with wave characteristics, the very same ones that we are studying in Physics right now.
Work Cited
"About Rainbows." Aug. 2005. University Corperation for Atmospheric Reseach. 2 Mar. 2008
"Why is the Sky Blue?" Science Made Symple. 1997. 2 Mar. 2008
Mirages
A mirage is a naturally-occurring optical phenomenon, in which light rays are bent to produce a displaced image of distant objects or the sky. The word comes to English via the French mirage, from the Latin mirare, meaning 'to appear, to seem'. This is the same root as for mirror. Like a mirror, a mirage shows images of things which are elsewhere. The principal physical cause of a mirage, however, is refraction rather than reflection. A mirage is not an optical illusion. It is a real phenomenon, and one can take photographs of it. The interpretation of the image, however, is up to the fantasy of the human mind.
Mirages occur when there is a rapid shift in air density in the atmosphere -- when the air at one level is a lot hotter than the air at an adjoining level.
This commonly occurs on summer days, when an asphalt road that has been baking in the sun heats the air directly above it, creating a sharp shift in air density levels near the ground. As light passes between the different levels, it bends, creating mirages. Normally, sunlight bouncing off an object (let's say a car) reflects in all directions. You see the car when your eyes detect this light. On an overcast day, you only see the light that bounces off the car straight toward you. This is how you see things most of the time.
On a sunnier day, the light heading straight toward you acts just like it usually does -- it doesn't move through different layers of air density, so it doesn't bend much. But some of the light that would normally hit the ground actually bends in midair because it moves from the cooler, denser air level into the hotter, less dense air right above the ground. As you can see in the diagram below, this produces an interesting effect.
|
|
The lower part of the light wave passes between the layers first, so it speeds up an instant before the upper part. The light that would ordinarily go straight to the ground bends upward and travels to your eyes. The effect is that you see the image of the car twice: once on top of the road, and once in the road surface. The light from the lower part of the car bends farther upward than the light from the top of the car, so the mirage image looks like a reflection. Your brain assumes that the light is traveling in a straight line, so it seems like there's a mirror image beneath the normal image. This mirage looks just like a puddle of water on the road because, like a puddle of water, it's reflecting what's above it. This sort of mirage is called an inferior mirage because it appears below the horizon.
Superior mirages are mirages that form above the horizon. This occurs when there is a cooler level of air lower than a warmer level of air, typically over icy landscapes or very cold water. This mirage causes you to see a scene much higher than it should be. For example, you might see a mass of land or a boat floating in midair. This situation might also distort images, making a boat seem much taller than it actually is.
Bibliography
http://mintaka.sdsu.edu/GF/mirages/mirintro.htmlhttp://www.islandnet.com/~see/weather/elements/supmrge.htm
http://www.sas.org/tcs/weeklyIssues/2004-09-10/gallery/index.html
Physics Explained, Rainbows, Mirages, Color of the Sky and Sunset
The Color of the Sky and Sunset:
In case you were ever one of countless people who have ever wondered to themselves why the sky was blue, then your answer will hopefully be cleared up. It all begins with the simple and complicated physics of it all. To commence understanding, first you must know that whenever any kind of light comes into contact with some sort of boundary between two transparent pieces of material, with different indices of refraction, a portion of this original light is reflected. On the other hand, a portion of its original light is also transmitted due to refraction.
The rainbow occurs because after raining, the droplets of water in the air act as their own tiny prisms, refracted and dispersing the wavelengths of light. As the sunlight goes into the water it reflects and disperses, and depending on the angle of refraction, shows a color in the rainbow. The colors vary due to the angle of refraction and the length of the wavelength. (http://www.howstuffworks.com/question41.htm)
http://inspirationalrainbows.com/images/desert_rainbow.jpg
Lastly, although many may believe they are the mind playing tricks on people, that is actually false. They truly do occur due to the refraction of light in the atmosphere and the changes in air temperature combined with the light. (http://mintaka.sdsu.edu/GF/mirages/mirintro.html)
In case you were ever one of countless people who have ever wondered to themselves why the sky was blue, then your answer will hopefully be cleared up. It all begins with the simple and complicated physics of it all. To commence understanding, first you must know that whenever any kind of light comes into contact with some sort of boundary between two transparent pieces of material, with different indices of refraction, a portion of this original light is reflected. On the other hand, a portion of its original light is also transmitted due to refraction.
To further understand this concept, the picture above shows the line (indicating the boundary) and the two spaces on either side as the transparent material. It then shows the types of reflection, absorption, and the path of light throughout its journey.
You may be wondering what any of this has to do with the answer to why the sky is blue. The previous information shows how the light gets used, some of it reflected, some refracted, some absorbed, and so on. Technically, the sky is blue “simply” because of scattered sunlight. Although we may see the sky as blue, in reality it is more on the violet end of the spectrum but the human eye is not as sensitive to see this. (Patterns in Nature) Continuing to look at the color of the sky, some people might wonder why we see more towards the blue end of the spectrum rather than the red. The answer to this question is that the blue and violet wavelengths are much shorter than red scattering. The idea that the sky was blue because of gases in the atmosphere also was brought up by a scientist named Rayleigh. There have been several theories tested and thought up of by previous experimenters to explain the idea of why the sky was blue.
The scattering of light in an atmosphere is a very important aspect to look at when asking the infamous question of why the sky is blue. Before, the visible spectrum of red and blue was discussed in relation to the color in the sky.1/lambda to the fourth power is the formula used to equate to the scattering of light by molecules.This makes sense because the red end of the spectrum has longer wave lengths than the blue and violet end. If you were to plug a longer wavelength into the formula, you would notice that it would be a much larger number under one, meaning a smaller number as a whole. When a shorter wavelength is plugged in, a smaller more manageable number is created. The atmosphere has a lot to do with the scattering of light. When the sun is at his highest point, or around midday 12 o’clock, it has to pass through the thinnest layer or atmosphere that it has all day. This explains why the sky tends to be brightest and clearer than any other point in the day; and also why you get sunburned or tanned more (since the sun is passing through the thinnest layer of atmosphere.)
This picture and all of the above information after Patterns in Nature was used fromPolarization; and The Human Eye.Again, the wavelengths are a huge part in why we see the sky as blue. The longer wavelengths of the reds and oranges tend to pass straight through, without being changed. The blues and violets are some what tampered with because the shorter wavelengths are far easier to be absorbed. When they are absorbed, they are then radiated and scattered into all different directions. Since the blue light shows up in all directions, you see the whole sky as being blue as a whole, rather than separate parts. For a moment, picture yourself at a beach; when you look out at the clear refreshing blue sky, you notice further out on the horizon there is a paler blue and then almost whitish color. Although this may never have been a mind-boggling thing to you, some people have also pondered this question as much as why the sky was blue. Since the horizon is much farther away from you, there needs to be more blue light at stronger amounts of it to reach you so that you see the same color closer up. However, this is not the case so you see a much lighter version of the blue color you see straight above you. (Blue Sky http://www.sciencemadesimple.com/sky_blue.html)
All of this wavelength information can also be used to help determine why the sunset ends up being red. The longer wavelengths in the early morning and late at night help to explain why the colors red and orange are more apt to show up. The sun goes down and has to go through a thicker atmosphere and therefore the longer wavelengths tend to be way more prominent. The light also must go farther to get to your visible eye while the sun rises and sets because it is on the horizon, rather than right above you. As I said before with the paler and lighter blues on the horizon, the sunrise and sunset is also on the horizon, so the longer wavelengths will get to you easier than the shorter blues and violet wavelengths. That is why you see the reds, oranges, and pinks when the sun sets and rises
http://members.aol.com/danglick01/Sunset1.jpg
Rainbows:
First, to understand rainbows, you must know that white light contains all of the colors of the visible pattern, or as we all know it, “ROYGBIV”. We are able to see these colors lets say, through a prism, because each color has its own wavelength that directs how it bends away, towards, or in any direction. For example, blue light typically refracts because of its shorter wavelength where as green refracts, but less than blue and so on. So when light is shown through a glass prism and it hits at just the right angle, the colors are refracted and dispersed, or scattered about to create the visible spectrum. Also, to create another visual, if sunlight was shown into a glass of water, the light would refract and bend and create a spectrum on the floor where you would see a column of your visible colors. (http://acept.la.asu.edu/PiN/rdg/rainbow/rainbow.shtml#top)
The rainbow occurs because after raining, the droplets of water in the air act as their own tiny prisms, refracted and dispersing the wavelengths of light. As the sunlight goes into the water it reflects and disperses, and depending on the angle of refraction, shows a color in the rainbow. The colors vary due to the angle of refraction and the length of the wavelength. (http://www.howstuffworks.com/question41.htm)
http://inspirationalrainbows.com/images/desert_rainbow.jpgMirages:
For many centuries, there have been stories of mirages where people claim to see things that in reality aren’t there, no matter how convinced they are. These “mirages” are created by two layers of air at quite different temperatures. As discussed earlier, when there is a boundary between two transparent materials, light is refracted and reflected. Mirages occur because when the air is at the ground, but not quite touching it, and becomes overheated, an image occurs. I’m sure at one point or another you have been able to see the heat in the air on the ground on a hot summer’s day. There is almost like a ripple effect where it looks like the air is bending and takes on wave like characteristics. (
http://www.unmuseum.mus.pa.us/mirage.htm)For many centuries, there have been stories of mirages where people claim to see things that in reality aren’t there, no matter how convinced they are. These “mirages” are created by two layers of air at quite different temperatures. As discussed earlier, when there is a boundary between two transparent materials, light is refracted and reflected. Mirages occur because when the air is at the ground, but not quite touching it, and becomes overheated, an image occurs. I’m sure at one point or another you have been able to see the heat in the air on the ground on a hot summer’s day. There is almost like a ripple effect where it looks like the air is bending and takes on wave like characteristics. (
Lastly, although many may believe they are the mind playing tricks on people, that is actually false. They truly do occur due to the refraction of light in the atmosphere and the changes in air temperature combined with the light. (http://mintaka.sdsu.edu/GF/mirages/mirintro.html)
Rainbows
The sun sends out waves of white light. When this white light enters a droplet of water, it diffracts into the different colors. The white light diffracts because each color refracts at a different angle. For example, red refracts at 42 degrees, and violet refracts at 40 degrees. Because each color refracts at a different angle, each color must come from a certain angle towards your eye. Due to this, rainbows are a cone with its apex at your eye. However, the horizon generally gets in the way. This is why the rainbow appears as an arc. However, if you look from a high point like an airplane or mountaintop, you can see a rainbow circle on the cloud layer below you.
Example of refraction in a raindrop: http://www.phy.ntnu.edu.tw/java/Rainbow/rainbow.html
Sources:
Patterns in Nature. 26 December 1999. Arizona State University. 2 March 2008. <http://acept.la.asu.edu/PiN/rdg/rainbow/rainbow.shtml#top>
How Stuff Works 2006. How Stuff Works. 2 March 2008 <http://www.howstuffworks.com/question41.htm>.
How Stuff Works 2006. How Stuff Works. 2 March 2008 <http://www.howstuffworks.com/question41.htm>.
Looking Into The Eye
This blog took a lot of work... but im glad it was for the blog versus just handing in a paper
-DLH
I spent way too long on this...(The human eye)
Although the human eye may seem small don’t mistake it for being a simple organ. The eye is only approximately one inch wide, one inch deep and 0.09 inches tall. The eye is made up of hundreds of key parts that work together to create your vision (howstuffworks.com). Without having eyes your life would be completely different.
Your eye is made up of three different layers, the sclera, the choroid, and the retina (all of them shown above). The sclera maintains the shape of eye and contains the cornea where all light passes through. The choroid is the second layer of the eye. This layer is extremely important because it provides blood to all the structures of the eye (howstuffworks.com). Without blood nothing will be able to function. The choroid contains two parts to it, the iris and the ciliary body. The iris is the adjustable colored diaphragm around the pupil which is the black opening on the eye. The ciliary body controls the size of the lens by contracting and relaxing it. The innermost layer of the eye is the retina. The retina contains two vital parts to it, rods and cones. The cones are responsible for color vision and detail while the rods are responsible for vision in low light. Another important part to the retina is the chemical it contains called rhodopsin. This chemical converts light into electrical impulses which the brain interprets as vision (howstuffworks.com). Below is a picture of a rod and a cone.
Seeing color also deals with the cones in our eyes. There are color-responsive chemicals in the cones that are called cone pigments and are very similar to the chemicals in the rods. There are three kinds of color sensitive pigments: red-sensitive pigment, green-sensitive pigment, and blue-sensitive pigment. Each one of the cones cells in each of our eyes has one of these pigments so that it is sensitive to that color. The human eye is amazing in that it can sense almost any gradation of color when, red, green, and blue are mixed (howstuffworks.com).
Normal vision is something doctors came up with after studying many people looking and trying to read off letters on a chart that is twenty feet away from them. 20/20 vision means that when you stand twenty feet away from the chart you can see what a “normal” human being can see. However, if you have 20/40 vision it means that you are no longer “normal” because you have to be twenty feet away from something to read or see it when a “normal” person can be forty feet away from it to see or read it. 20/200 vision is absolutely horrible vision and is the legal cutoff for blindness in the United States. People can also have better vision than the norm. If you have 20/10 vision then you can see something at twenty feet away when most “normal” people have to be ten feet away to see it (howstuffworks.com).
Some problems with the eyes include nearsightedness, farsightedness, and even blindness. Nearsightedness is when you can see objects up close well but far away objects are tough to see. This is caused by an eye ball that’s too long, or a lens system that has too much power to focus (howstuffworks.com). This problem can be corrected with the use of a concave lens as seen below:
Farsightedness is just the opposite. This occurs when a person is able to see distance objects especially well and has trouble seeing close up objects. This is caused by an eye ball that is too short, or by a lens system that has too little focusing power (howstuffworks.com). This problem can be corrected with the use of a convex lens as seen below:
There are many things that can lead to blindness. Cataracts, glaucoma, or just trauma to the eye are only a few of the things that can lead to blindness. A cataract is cloudiness in the lens that blocks light from reaching the retina. This condition usually happens as we age. As it worsens, it can require surgery to remove the lens and replace it with an intraocular lens. Glaucoma is caused when the aqueous humor of the eye does not drain out correctly. This causes pressure to build up on the eye. When this happens it causes cells and nerve fibers in the back of the eye to break and die. This can be treated with surgery or medications only. Another way to go blind would be by receiving trauma to the eye itself (howstuffworks.com). Getting hit, being poked, or having certain chemicals getting into the eyes can prevent adequate vision.
Brain, Marshall. “How Stuff Works”. March 02, 2008.
Your eye is made up of three different layers, the sclera, the choroid, and the retina (all of them shown above). The sclera maintains the shape of eye and contains the cornea where all light passes through. The choroid is the second layer of the eye. This layer is extremely important because it provides blood to all the structures of the eye (howstuffworks.com). Without blood nothing will be able to function. The choroid contains two parts to it, the iris and the ciliary body. The iris is the adjustable colored diaphragm around the pupil which is the black opening on the eye. The ciliary body controls the size of the lens by contracting and relaxing it. The innermost layer of the eye is the retina. The retina contains two vital parts to it, rods and cones. The cones are responsible for color vision and detail while the rods are responsible for vision in low light. Another important part to the retina is the chemical it contains called rhodopsin. This chemical converts light into electrical impulses which the brain interprets as vision (howstuffworks.com). Below is a picture of a rod and a cone.
Seeing color also deals with the cones in our eyes. There are color-responsive chemicals in the cones that are called cone pigments and are very similar to the chemicals in the rods. There are three kinds of color sensitive pigments: red-sensitive pigment, green-sensitive pigment, and blue-sensitive pigment. Each one of the cones cells in each of our eyes has one of these pigments so that it is sensitive to that color. The human eye is amazing in that it can sense almost any gradation of color when, red, green, and blue are mixed (howstuffworks.com).
Normal vision is something doctors came up with after studying many people looking and trying to read off letters on a chart that is twenty feet away from them. 20/20 vision means that when you stand twenty feet away from the chart you can see what a “normal” human being can see. However, if you have 20/40 vision it means that you are no longer “normal” because you have to be twenty feet away from something to read or see it when a “normal” person can be forty feet away from it to see or read it. 20/200 vision is absolutely horrible vision and is the legal cutoff for blindness in the United States. People can also have better vision than the norm. If you have 20/10 vision then you can see something at twenty feet away when most “normal” people have to be ten feet away to see it (howstuffworks.com).
Some problems with the eyes include nearsightedness, farsightedness, and even blindness. Nearsightedness is when you can see objects up close well but far away objects are tough to see. This is caused by an eye ball that’s too long, or a lens system that has too much power to focus (howstuffworks.com). This problem can be corrected with the use of a concave lens as seen below:
Farsightedness is just the opposite. This occurs when a person is able to see distance objects especially well and has trouble seeing close up objects. This is caused by an eye ball that is too short, or by a lens system that has too little focusing power (howstuffworks.com). This problem can be corrected with the use of a convex lens as seen below:
There are many things that can lead to blindness. Cataracts, glaucoma, or just trauma to the eye are only a few of the things that can lead to blindness. A cataract is cloudiness in the lens that blocks light from reaching the retina. This condition usually happens as we age. As it worsens, it can require surgery to remove the lens and replace it with an intraocular lens. Glaucoma is caused when the aqueous humor of the eye does not drain out correctly. This causes pressure to build up on the eye. When this happens it causes cells and nerve fibers in the back of the eye to break and die. This can be treated with surgery or medications only. Another way to go blind would be by receiving trauma to the eye itself (howstuffworks.com). Getting hit, being poked, or having certain chemicals getting into the eyes can prevent adequate vision.
Brain, Marshall. “How Stuff Works”. March 02, 2008
Physics of a Rainbow
Mr. Wirth,
My blog post essay is on my own blog. I wrote the blog on there last week and inserted pictures and now I'm not able to transfer the entire thing onto the class page altogether. So if you click my link you will see my post.
Thanks,
Courtney Sant
My blog post essay is on my own blog. I wrote the blog on there last week and inserted pictures and now I'm not able to transfer the entire thing onto the class page altogether. So if you click my link you will see my post.
Thanks,
Courtney Sant
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