It's really hard for me to concentrate in this class because i'm not interested in any of it and i feel it is presented in a bland way

winter break blog post

Polarization- is a property of trannsverse waves which describes the orientation of the oscillations in the plane perpendicular to the wave's direction of travel. This concept is used in areas of science and technology dealing with wave propagation, such as optics, seismology, and telecommunications. In electrodynamics, polarization characterizes electromagnetic waves, such as light, by specifying the direction of the wave's electric field. Longitudinal waves such as sound waves in liquids and gases do not exhibit polarization, because for these waves the direction of oscillation is along (and thus is uniquely determined by) the direction of wave's travel. In contrast, the direction of the (electric field) oscillation in electromagnetic waves is not uniquely determined by the direction of propagation. Similarly, the direction of shear stress in a transverse sound wave in a solid can have any orientation in the plane that is perpendicular to the propagation direction. The term polarization thus describes the possible orientations of the oscillatory process in the plane perpendicular to the transverse wave's path.

Ch. 20 #63

Lucien Rouse
The leyden jar is considered to be the first ever capacitor, and it was invented by Pieter van Musschenbroek. It consisted of a metal outer part, with a brass rod coming out of the top. The brass passes through a wood coating. When a charge is applied, the charge is kept at equilibrium by the metal coating and the wood, and cannot be discharged without further action.
The Wimshurst machine was invented by James Wimshurst to create strong electric charges. Two insulated disks in the center of the machine are what drive it. As they rotate, a strong charge is produced.

i cannot get my pictures to work, but here are the URL's
http://www.rfcafe.com/references/electrical/Electricity%20-%20Basic%20Navy%20Training%20Courses/images/Figure%209.jpg
http://www.sciencefirst.com/pctr/10069.JPG

Winter Post...well at this point spring break post

THE HUMAN EYE

Our human eye is a complex organ with a variety of layers and muscles. Obviously, it is used to help humans use thier sense of sight.The human eye is unique in that it accommodates for different light intensities and also focuses light rays that come from different distances from the eye. Light is then converted into impulses and sent to the brain where this image is perceived as what it looks like. Vision is very dependent on light. The light rays are reflected off object and then make their way into the eye. The light rays enter the eye through the cornea and the cornea refracts the light as it enters the eye. After passing through the cornea the light rays pass through the opening called the pupil. The iris is the part of the eye that controls the dilation of the pupil. This allows a certain amount of light into the eye. However, many humans experience vision problems that either impair their vision or prevent them from seeing altogether. At 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. 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 also 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:MusclePrimary FunctionMedial rectusmoves eye towards noseLateral rectusmoves eye away from noseSuperior rectusraises eyeInferior rectuslowers eyeSuperior obliquerotates eyeInferior obliquerotates eyeAfter 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.

Winter Blog Post

Physics Explained: Rainbows, Mirages, Color of Sky & Sunsets.

*To understand the phenomenon of rainbows, mirages, and the color of the sky and sunsets, we must first look at understand the concepts of how light and optics work.

*Speed of light in a medium is determined by the interactions between light and the atoms that make up any particular medium. Some terms to familiarize ourselves with are index of refraction and reflection. The index of refraction is in a medium, the ration of the speed of light in a vacuum to the speed of light in that medium. Reflection occurs when light traveling from a region strikes a boundary at an angle and produces a wave that is bounced off of that boundary.

*A mirage can occur on a summer day. When you are driving down the road you see a looks to be a reflection of an oncoming car in a pool of water. However, the pool disappears as you begin to approach it. This mirage is the result of the Sun heating the road. The extremely hot road heats the air above it and a thermal layering of air is produced, which causes any light traveling towards the road to gradually bend upwards. This makes the light appear to be coming from a reflection in a pool on the road.

Basically...a mirage is seen on the surface of the road. Light bends upwards into the eye of the observer and the bottom of the wave front moves faster than the top-creating the mirage.

*Another concept we must identify is dispersion. Dispersion is when white light separates into a spectrum of colors when it passes through a glass prism. White light that is directed through a prism is dispersed into bands of different colors. The different colors of light bend different amounts when they enter into a medium. Different colors of visible light have different speeds when going through a medium.

*A prism is not the only way of dispersing light. A rainbow is actually a spectrum formed when sunlight is dispersed by water in the atmosphere (light rain or humidity). Sunlight that later falls on the water droplets is refracted and because of dispersion each color is refracted at different angles. And back at the top of the surface of the water droplet some light fore goes internal reflection and on the way

out of the droplet the light is again refracted and dispersed.

Basically...a rainbow forms when white light is dispersed as it enters and reflects at the inside boundaries and exits through a rain droplet. And due to dispersion only one color from each raindrop reaches an observer-creating a rainbow.

Work Cited:

1. Glencoe Science, Physics Principles and Problems Text Book. (Our textbook)

2. http://www.howstuffworks.com/question41.htm

#63

History of Science:


*The Leyden Jar:


*a German scientist named Ewald Georg von Kleist invented the capacitor in November of 1745
*a little while later a Dutch professor, Pieter van Musschenbroekcame up with a very similar device called the Leyden Jar
*this is typically thought as the first capacitor
*this is generally a simple device
* it is made up of a glass jar, half filled with water and lined inside and out with metal foil
-(the glass acts as the dielectric)
-(water used to be thought to be the key ingredient)
*there was usually a metal wire or chain driven through a cork in the top of the jar
*the chain was then hooked onto something that would give a charge
-(probably a hand-cranked static generator)
*once the charge was delivered the jar would hold 2 equal (opposite) charges in equilibrium until they were connected with a wire...which would produce a small spark or shock

Scribe 3.31.08

ANALYSING CIRCUITS:
Series Circuit:
*a series circuit in which there is only one current path with multiple drops in potential along the path
*(ex) Christmas lights not working
Current in a Series Circuit:
*the current is the same in all components of a series circuit
*I=I1=I2=I3=...
Potential in a Series Circuit:
*the sum of the potential drops in a series circuit is equal to the source potential
*V=V1+V2+V3+...
Resistance in a Series Circuit:
*the equivalent resistance of a series circuit is equal to the sum of the resistance of its components
*Req=R1+R2+R3+...
*ammeters must be connected in series
-all current has to flow through it
SERIES CURRENT SUMMARY:
*only 1 path
*derivation of series circuit Req
*Given V=V1+V2+V3+... where V=IR
*Then IReq=I1R1+I2R2+I3R3+...
*But I=I1=I2=I3=...
*So Req=R1+R2+R3+...
Parallel Circuits:
*a parallel circuit is one in which there is only one potential drop with multiple paths for current to flow across the potential drop
Current in a Parallel Circuit:
*total current in a parallel circuit is the current supplied by the source and is equal to the sum of the branch current
*I=I1+I2+I3+...
Potential in a Parallel Circuit:
*the potential drop across each branch of a parallel circuit is the same as the source potential
*V=V1=V2=V3=...
Resistance in a Parallel Circuit:
*the reciprical of Req of a parallel circuit is equal to the sum of the recipricals of the brance resistance
*1/Req=1/R1+1/R2+1/R3+...
*Voltmeters must be connected in parallel