hey wirth im back

Scribe Post

Homework: Magnetism-Worksheet #1

Today in class we learned about The Right Hand rule, it tells the direction of the magnetic field around a conductor that is caring a current. The thumb pointing upwards tells the direction of the current, and the fingers which curl around tell the direction of the magnetic field. We also learned about solenoids which is wire wrapped around something often metal. Solenoids produce a magnetic field when an electrical current flows though them. Yes the Type-R does has solenoids.

Problem 63

Pieter van Musschenbroek invented the first capacitor, the leyden jar. It has a brass rod coming out of the top of an outer metal part. There is wood coating through which the brass goes through. The metal coating and wood keep the applied charge at equilibrium and do not allow it to be discharged. James Wimshurst invented the Wimshurst machine which creates strong electric charges. It has two insulated disks in the center of the machine which drive it, and as they rotate a strong charge is produced.

Problem No. 63, yo!

During the 17th and 18th centuries, several new inventions were developed to conduct tests and measure static electricity. The Leydan Jar for example, was a simple jar coated both inside and outside with foil. An electrode was then connected to a piece of foil inside the jar, which allowed electricity to be conducted. The charge then moves to the electrode with a generator. Another example of a fantastic machine was the Wimshurts machine. This machine was an electrostatic generator. In the generator there were rotating disks with metal attached to them. Though the only way it can be used is with the process of induction.

-Marcy

Chapter 24.1 #10-15

10. A magnetic field is definately present in nature because just use a magnet and you can see that they are vector quanities and exist.

11. Some magnetic forces around us are of course in magnets, by using a compass needle and magnet to see the affect it has on the compass to see the field. Also using bar magnets getting opposite poles facing each other will show the impact of magnetic fields.

12. If the currents are in the same direction, they will repel each other but if they are facing in opposite directions, the will attract because as the saying goes "opposites attract" and that is true in this case when dealing with magnets.

13. The magnetic field around a straight, current-carrying wire is numerous circular concentric circles around the wire.

14. The observable differences that will result are that the iron fillings will move opposite their original positions because they rely on the polarity of the poles of magnets and if those change, so do they.

15. a) The rod could behave this way because the poles are being moved and so the rods are probably just now attracting each other because of the switch because opposites poles attract and like ones repel.
b) The type of replacement rod that is used is a neutral rod.

63

Throughout the 17th and 18th centuries there were several new inventions developed to measure static electricity. One of these creations was the Leydan Jar. It made up of a jar coated inside and out with foil. Then an electrode was connected to the inside foil to conduct electricity. Then the charge moves to the electrode with a generator. Another invention was the Wimshurts machine. The machine is an electrostatic generator. The generator has rotating disks that carry metal on them. If the generator is used it is through the process of induction.

March 31

Equivalent resistance:
-the resistance seen by the source.
-equal to potential difference (V)/current (I)
Series Circuit:
-circuit with only one current path, with multiple drops in potential along the path
-example christmas tree lights
-current is the same in all components (I=I1=I2=I3=...)
-the sum of the potential drops is equal to the source potential (V=V1+V2+V3+...)
-the equivalent resistance is equal to the sum of the resitances and its components (Req=R1+R2+R3+...)
-ammeters must be connected in a series circuit so all current flows through it
Parallel Circuit:
-circuit with only one drop in potential with multiple paths for the current
-total current is the current supplied by the source. equal to the sum of the brance currents (I=I1+I2+I3+...)
-source potential is equal to the potential drop across each branch (V=V1=V2=V3=...)
-the reciprocal of Req is equal to the sum of the reciprocals of the resistance in each branch (1/Req=1/R1 + 1/R2 + 1/R3+...)
-voltmeters must be connected in a parallel circuit

Class Scribe Post-4/1

Class Lesson on 4/1-

Today we learned about the different meters in a circuit. Voltmeter, which is the measure of the potential difference between two distinct points on a circuit. It also has an extremely high internal resistance. We also learned about the ammeter, which is a measure of the current that passes through only one point of a circuit. In the ammeter, it has an extremely low internal resistance, differing from that of the voltmeter. The ammeter also creates an extremely small voltage drop while the voltmeter draws an extremely small current. At the beginning of the lesson we also discussed the difference between the potential difference in a parallel and series circuits through diagrams. We also did practice problems on white boards to better understand and grasp the concepts from previous lessons on circuits. The unit test was announced to be Monday on the material we learned today and the rest of the circuit stuff.

Chapter 20: #63

Throughout the 17th and 18th centuries, many breakthrough inventions were created in the field of electricity. One of these inventions was the Leyden Jar. It was constructed by taking a jar. The scientist would then coat the inside in foil and do the same for the outside of the jar. They would then connect an electrode to the inside foil in order to conduct electricity. The jar works by charging the electrode with a generator. The charge then moves into the foil. Another popular invention was the Wimshurst Machine. It was built by putting two discs spinning the opposite way. their would then be a spark gap between two metal spheres. The machine was poweered mechanically, not electrically. when the machine was cranked, it would make a spark between the two spheres.

3/25/08 Scribe

Today in class we went over electrical circuits. We started the class with a new list of scribes and did a warm up using circuit in a sentence. After that we started taking notes. One of the first ideas was the definition of a circuit which is a closed loop or path. Also charged particles move along said path, and which a electric current can exist and is formed by potential difference. In addition to that we went over some electrical schematics then we watched a four-minute video on electrical circuits. Some circuit elements that we went over included source elements, load elements, control elements and path elements. Finally we went over terms and definitions and learned the formula I = Δq/t and did some practice problems. At the end of the class we did a ticket to get out the door.
There was no homework!
justin d

we

#63

One thing used in the seventeenth and eighteenth century to study static electricity was the Leyden jar. This device consisted of 2 conductors separated by an insulator, usually tin foil on either side of a piece of plastic or glass. It is used by being charged by a static generator. The electricity flows into the jar and stays there. After being charged, a person can connect the conductors, causing a spark and the charges to discharge, resulting in the jar to be neutralized.
Another thing used to study static electricity is the Wimshurts machine. This decive is an electrostatic generator that has rotating disks with metal carriers in them. When used, the charges are produced by induction.

Problem 63

The Leyden jar is an early device for storing electric charge invented in 1745 by Pieter van Musschenbroek(1692–1761). It was the first capacitor. Leyden jars were used to conduct many early experiments in electricity.
The Wimshurst machine is an electrostatic device for generating high voltages developed between 1880 and 1883 by British inventor James Wimshurst (1832 – 19003). It has a distinctive appearance with two large contra-rotating discs mounted in a vertical plane, two cross bars with metallic brushes, and a spark gap formed by two metal spheres.

Chapter 20-#63

Chapter 20-#63

Several Devices were used in the seventeenth and eighteenth centuries to help scientists learn more about static electricity. One example is the Leyden Jar. This device was the first to be capable of storing large amounts of charge. First constructed in 1745, it was a glass vial filled partiallly with water and a thick conducting cable and the vial was sealed at the top with a cork. It was used to kill animals through electric shock in early households and was a breakthrough in the study of electrostatics. Another device used to study electrostatics was the wimshurst machine. Constructed of a generator, glass disks and metal carries, this device sent charges through induction. It is an excellent example of charge separation and a great early discovery that helped scientists learn more about static elctricity.

Blog Post for Fridays Class

• Went over homework


• Worked on a lab about static electricity

In this static electricity lab we detected the presence of an electric charge using a known charge. We used an electroscope to determine different charges of materials. We then built a table showing different charges of different objects, such as the black rod and the fur or the clear plastic rod and the silk.

• We were given graded homework from chapter 20 in the physics book.

question 63

The most important devises used to study electric energy in the 17th and 18th century were the Ledyen Jar and the Wimshurst machine. The Ledyen jar was discovered first in 1745, by Pieter van Musschenbroek. It was the first device that was able to store large amounts of electrical energy. With in a year of its creation, William Watson made some improvements on the constriction of the machine. It is a cylindrical container, made out of an insulator, with a layer of metal foil on either side of the cylinder. The outer side of the cylinder is grounded, while the inner side is given a charge. This enables the container to store electrical energy. The Wimshurst machine was created in the 1880s, by James Wimshurst. Unlike the Ledyen jar, the Wimshurst machine generates electrical energy, opposed to storing it. It is a machine consisting of two large contra-rotating discs that are mounted in a vertical plane, with two cross bars with metallic combs/brushes and a spark gap that is formed by two metallic spheres. The machine generates high voltages through induction. Within the machine there are quadrants of positively and negatively charged space, as the discs rotate, the metallic combs conducts the negative and positive charges away. Before this occurs, the machine already has an imbalance of charges, from human contact and such while it was being set up, and running the machine merely amplifies that imbalance.

Super physics fun time!

Here are some of the key important things that we learned yesterday during our fulfilling 8th period physics class:

-Charges in a system may be transfered from one object to another.

-Objects become electrically positive or negative when they have a deficiency or excess amount of e-.

-The formula Q=ne
q= total charge
n= number of elementary charge
e= elementary charge

Coulombs Law: The electrostatic force between two point charges is:
Directly proportional to product of charges, inversely proportional to square of distance between centers.

Formula: Fe= K(q1q2/r^2)
r= distance between centers of q1 and q2
k= electrostatic constant (k= 8.99 x 10^9 n-m^2/c^2

End of post.

Keil Kunzer
Mr. Wirth
Physics R
4 March 2008
The Human Eye

The human eye is a very complex structure of our body. Our eye gives a person the sense of sight and vision. The eye helps us decipher objects, colors, and shapes; it also can detect the difference between dim and bright light. There are many different parts to the human eye but the main ones are the iris, pupil, cornea, lens, and retina. Light waves enter the eye first through the cornea which is the clear part in the center of the eye. Then all the light gets processed in the pupil which is part of the iris. There are also many muscles in the eye that allow it to move and allow for our pupils to get bigger or smaller depending on the brightness of light rays. The human eye consists of many different complex parts, without these we would not have the ability of one of our most important senses (Montgomery).
Human vision is an extremely complex and interesting subject. The basic light sensing structure of the eye is the retina, which consists of both rods and cones. The rods and cones process the light through a chemical reaction, which then creates electrical impulses to the eye’s nerve. After the electrical impulses are sent to the nerve, this information is then sent to the brain where it is processed and then interpreted as light. In the cones are three different color sensing pigments. These colors include red, green, and blue color sensitive pigments. The eye can sense any combination of these colors unless a person has a color blindness disorder. Colorblindness occurs when one of the color pigments in the cones are not functioning properly. Colorblindness occurs in females in less than one percent of the population, but in males it occurs in eight percent of the population. The ability to see light and color is an extremely special feature of the human body, and it is something that many people take for granted.
Just because most everyone have the same eye structure, does not mean every human has the same vision. If someone is considered to have normal vision their vision is 20/20. That means the majority of the human population can see what you see at twenty feet. 20/10 vision is better than normal vision because it means you can see twenty feet of what a normal person can see when standing ten feet away from a vision chart. In the United States a person is legally blind when their vision is 20/200. A few vision problems a person might have are nearsightedness or farsightedness. When a person is nearsighted they have difficulty seeing objects that are close to them, which is caused by an elongated eyeball. The opposite is true for farsighted people, which is when people have trouble seeing objects farther away from them caused by a shorter eyeball. Another vision problem a person might develop is an astigmatism. An astigmatism is when the cornea is uneven or curved. This causes distortion to a person’s vision, yet this can be corrected with a lens that is fitted to correct the uneven cornea. The human vision system is an extremely complex structure of the human body (Bianco).
The human eye is an amazing organ, and gives people the great sense of vision. There are many people who are unable to see the everyday occurrences in their lives due to vision problems. It would be extremely difficult to live not being able to comprehend colors and frequencies of light.



Works Cited

Bianco, Carl. "How Vision Works." How Stuff Works. 4 March 2008
<http://health.howstuffworks.com/eye.htm>

Montgomery, Ted. "Anatomy, Physiology and Pathology of the Human
Eye." 4 March 2008 <http://health.howstuffworks.com/eye.htm>

The Human Eye

Luke Seavitt

Physics blog post

Wirth

The Eye:

Although the human eye is one of the smallest human organs it is one of the most complex. It is composed of several different parts that all work together to help us see the objects that we look at. In order for the eye to maintain its shape it has something called the sclera which is the outermost layer of the eye. The front sixth of the sclera is called the cornea and this part of the eye is also clear. All light that is seen by the human eye has to pass through the cornea. Also attached to the sclera are muscles that provide movement to the eye. These muscles are called extrocular muscles. Blood vessels that supply blood to the eye are located in the second layer of the eye which is called the choroid. The front part of the choroid is composed of two parts the ciliary body and the iris. The ciliary body contracts and relaxes to control the size of the lens for focusing. The iris is the colored part of your eye and is determined by the color of the tissue and pigment cells. The iris itself has two muscles. It has the dilator muscle which makes the pupil larger allowing more light through the eye and making the iris smaller. The sphincter does the opposite of the dilator and makes the pupil smaller by increasing the size of the iris allowing for less light to go through the eye. The intermost layer of the eye is the retina which is the light sensing part of the eye. It contains cells called rod cells that are in charge of vision in low light. It also has cone cells which are responsible for color vision and detail. Another part of the retina is located in the back called the macula. In the center of the retina is something called the fovea centrails which is responsible for seeing small details. Also in the retina is something called the rhodopsin that converts light into electrical impulses to send to the brain to interpret the visions. The retina also has nerve fibers at the back of the eye which form the optic nerve, which conducts the electrical impulses to the brain. The spot where the optic nerve and blood vessels exit the retina is called the optic disk. This area is a blind spot on the retina because there are no rods or cones at that location. However, you are not aware of this blind spot because each eye covers for the blind spot of the other eye. In order for the scela to move the eye it has six different muscles to move the eye. The medial rectus which moves the eye towards the nose and the lateral rectus which does the opposite of the medial rectus and moves the eye away from the nose. It also has the superior rectus which raises the eye and the inferior rectus which lowers the eye. Lastly it has the superior oblique and inferior oblique which both rotate the eye.

Light and Color:

The eye perceives light first through the cornea then the aqueous humor, lens and vitreous humor. Eventually the light reaches the retina which is the light sensing structure. It contains two cells which are rods and cones. The rods handle the vision in low light and the cones handle color vision and detail. When light contacts these two types of cells, a series of complex chemical reactions occurs. This creates electrical impulses that in the optic nerve. In order to see color the eye has color responsive chemicals in the cones called cone pigments and they are very similar to those found in the rods. The retinal portion of the chemical is the same, however the scotopsin is replaced with photopsins. There are three kinds of color-sensitive pigments, red, green, and blue sensitive pigments. Each cone has one of these pigments so it is sensitive to that color. The peak absorbancy of blue-sensitive pigment is 445 nanometers, for green-sensitive pigment it is 535 nanometers, and for red-sensitive pigment it is 570 nanometers.

Refraction:

The eye has multiple angulated surfaces that cause light to bend. These are the interface between the air and the front of the cornea, the interface between the back of the cornea and the aqueous humor. Also the interface between the aqueous humor and the front of the lens and the interface between the back of the lens and the vitreous humor. When every one of these are working perfectly, light makes it through these four interfaces and arrives at the retina in perfect focus.

Normal Vision and Vision Problems:

The normal vision of a human being is 20/20 vision. This is determined by looking at the Snellen eye chart at a distance of 20 feet. If you have 20/20 vision, it means that when you stand 20 feet away from the chart you can see what a "normal" human being can see. However, not all people have perfect 20/20 vision. People can be nearsighted or farsighted meaning that they can either only see up close or they can only see from far away. To fix their vision many people wear eye glasses or contacts. There is also another problem that can occur with the eye called Astigmatism, which is an uneven curvature of the cornea and causes a distortion in vision. To correct this, a lens is shaped to correct the unevenness.

Bianco Md., Dr. Carl. "How Vision Works." How Stuff Works. 1998. 4 Mar. 2008 .

Myers, David G. Psycgolgy . VIII. New York: Worth Publishers, 2007.

Fiber Optics - John Tedesco

John Tedesco

Mr. Wirth

Physics R

3 March 2008

Physics Blog Post: Fiber Optics

Fiber Optic Cables are one of the most widely used forms of sending information in the twenty first century. Fiber Optic cables are one of the fastest ways of communication, whether it is through the internet, television, or other devices such as telephone (How). In addition, they are very reliable and efficient, drawing more and more companies to use them each year. Millions of Americans use fiber optics in their internet cables instead of DSL. In addition, fiber optic powered internet is light years faster than road runner, something we think is fast. Many major Metropolitan cities such as Pittsburgh are using fiber optic cables for the majority of their internet use.

Many people are not familiar with this new and efficient technology. Fiber optics is a thin piece of glass about the same size of a single human hair. These thin strands of glass are packaged together in cables and are used to transfer information. Fiber optics consists of three main parts. The core is in the center and is pure, thin glass used to carry the light through the cable. Around the core is the cladding, which provides as a barrier in order to keep the light inside of the core (How). This is able to occur due to total internal reflection, which is when light is unable to escape from the core because of the properties of the cladding. If light tries to escape the core and move onto the cladding, it is unable to due to the difference in the indices of refraction between the core and the cladding (Homework). Surrounding the cladding is the buffer coating, whose only function is to minimize damage to the fiber optics. Thousands of fiber optic cables are then bundled up and are surrounded by jackets, making them the cables that we know today.

[img]http://static.howstuffworks.com/gif/fiber-optic-fiber.jpg[/img]

There is a vast amount of physics behind the uses of fiber optics. All of it surrounds the principle of total internal refection. Total internal reflection is when light cannot pass from one medium to another because of the differences in the indices of refraction. In fiber optics, light is trapped in the core, because the angle of incidence at the surface of the cladding is greater than the critical angle (Homework). This means that the light remains trapped inside of the core and continues to travel at 300,000,000m/s through the cable. This results in the most efficient and by far the most affordable form of communication in the world today.

[img]http://hsc.csu.edu.au/senior_science/core/info_systems/9_4_6/Laserpath.gif[/img]

Fiber optics holds many advantages when compared to other forms of communication present in modern times. It is more efficient, less expensive, it takes up less space, it is faster, it is non-flammable since it uses light instead of electricity, it uses less power, and it can be used in medical imaging (How).

Fiber optics is by far one of the most promising technologies of the day. Taking advantage of light, fiber optics is one of the fastest forms of communication in the world, and it holds promising results for the future.

Citation

"Homework Help: Science: Physics: Fiber Optics." Jiskha Homework Help. 2 Mar 2008 .

"How Fiber Optics Work." How Stuff Works. 2 Mar 2008 .

http://hsc.csu.edu.au/senior_science/core/info_systems/9_4_6/Laserpath.gif