Ch24-26_HallowellC

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=Chapter 24 Guide Questions= 5. Describe Maxwell's experiment.



=Chapter 25 Guide Questions=

=Pre-Lab: What is the relationship between intensity and angle of polarization?=

1. The objective is stated in the title. What is your hypothesis? (Attempt to answer the question, to the best of your knowledge.) As the angle of polarization increases from 0 towards 90, the magnitude of the resulting intensity will decrease. This means that they are inversely proportional from 0 to 90 degrees. As the angle increases from 90 towards 180, the magnitude of the resulting intensity will increase as well. This means that they are directly proportional from 90 to 180 degrees.

2. What is the rationale for your hypothesis? (Provide detailed reasoning here. This may take the form of a list of what you already know about the topics, with a summary at the end.) I developed this hypothesis based on the equation,. I was able to use some example angles to see that from 0 to 90 degrees, the angle of polarization is inversely proportional to intensity. I was also able to find out that when the angle increases from 90 towards 180, the angle of polarization is directly proportional to intensity.

3. How do you think you might test this hypothesis? (What might you measure and how?) I believe we will be able to test this using two polarizers and a sensor that can detect the intensity of a beam of light. I believe that I will be able to shoot a beam of light through two polarizers with varying angles between them and measure the intensity of the resulting beam of light.

4. Read the procedure and calculations. Make any tables in order to organize your data and calculations.

5. Light is shown through a set of 2 polarizing filters. When is transmitted light at maximum intensity? Minimum intensity? It is transmitted at maximum intensity when the angle between the 2 filters is 0 degrees. It is transmitted at minimum intensity when the angle between the 2 filters is 90 degrees.

6. What is the relationship of the intensity of transmitted light to the angle of the polarizers between 0 and 90 degrees?

The intensity of transmitted light is inversely proportional to the angle of the polarizers between 0 and 90 degrees.

=Physics Classroom Summaries=

__**Lesson 1d (Method 4)**__
An electromagnetic wave is a transverse wave that has both a magnetic and electrical component. These kind of waves vibrate in more than one plane (3D). A light wave is a type of electromagnetic wave. A light wave that is vibrating in more than one plane is referred to as unpolarized light. Polarized light waves are waves that vibrate on a single plane. There are various ways to polarize light.
 * What is an electromagnetic wave?**

A polaroid filter will block out one of the two planes of the light. After going through the filter, the light wave has one half of the original intensity. The polaroid filter is able to polarize the light due to its material and orientation to the wave. The filter has many long chain molecules that are stretched across the filter all in the same direction. These help to block one of the planes of light.
 * How do you polarize by use of a polaroid filter?**

Unpolarized light can be polarized by being reflected off non-metallic surfaces. This polarization is dependent on the angle that the light approaches and the material that the surface is made of.
 * How do you polarize by reflection?**

Light is polarized by refraction when a beam of light passes from one material into another material. The path of the beam changes its direction and undergoes some polarization when at the surface of the two materials.
 * How do you polarize by refraction?**

Light is polarized when traveling through a medium as well. After the light strikes the atoms of the material many times, the vibrating electrons create their own electromagnetic waves. This causes a lot of absorption and reemission of light, which scatters the light and polarizes it as well.
 * How do you polarize by scattering?**

Polarization is seen in glare-reducing sunglasses. The lens act as filters to the light waves. Polarization is also used in the production of 3D movies.
 * What are some applications of polarization?**

__**Lesson 2a-f (Method 4)**__
It is the range of frequencies of electromagnetic waves. The spectrum is broken into several subdivisions based on how the waves interact with certain types of matter. The longer the wavelength means a smaller frequency. The shorter the wavelength means a higher frequency.
 * What is the electromagnetic spectrum?**

It is the region located to the right of the infrared region and to the left of the ultraviolet region. It is the only small part of the main spectrum that humans can see. The wavelengths of this spectrum range from about 700 nm to about 400 nm. The spectrum is also known as ROYGBIV. Each wavelength in the spectrum represents a color. The speration of light into different colors is called dispersion.
 * What is the visible light spectrum?**

They are the color-sensing cells of the retina. There are three different cones that are each sensitive to different wavelengths. These cones are red cones, green cones, and blue cones. The green cone is the most sensitive, followed by blue and then red. They each pick up the few colors that are around each of them. (For example, green picks up some yellows and blues in addition to green.) These cones relay this information to the brain.
 * What are color cones?**

When light hits objects, those objects have a natural frequency. If this frequency matches that of one of the colors in the light, then that part of the light is absorbed. The natural frequency of the object is determined by the electrons of the atoms. If the vibrations of the electrons move from one atom to another and are reemitted on the other side, then these frequencies of light waves are said to be transmitted. If the vibrations of the electrons do not pass from atom to atom and instead are reemitted as a reflected light wave, then the frequencies of light are said to be reflected.
 * What is light absorption, reflection, and transmission?**

Chemicals that are capable of selectively absorbing one or more frequency of white light.
 * What are pigments?**

The three primary colors of light are red, green, and blue. When they are added together, they make white light (visible light). When you pair up each of the primary colors with one another, you make magenta, cyan, and yellow. These are sometimes known as the secondary colors of light. Complementary colors are any two colors of light that when mixed together in equal intensities produce white.
 * How do you add colors?**

It is the process in which the ultimate color appearance of an object is determined by beginning with a single color or mixture of colors and identifying which color or colors of light are subtracted from the original set. This is the rule for pigments and colors: Pigments absorb light. Pure pigments absorb a single frequency or color of light. The color of light absorbed by a pigment is merely the complementary color of that pigment.
 * What is the process of color subtraction?**

They are magenta (absorbs green light), cyan (absorbs red light), and yellow (absorbs blue light).
 * What are the primary colors of paint?**

The atmosphere, with its many gases, is able to scatter the colors with higher frequencies (BIV) and allows the colors with lower frequencies (ROY) to pass through. This gives the sky a blue color because our eyes are most sensitive to blue. The sun appears yellow midday because our eyes are most sensitive to yellow and light tends to be most rich with yellow light frequencies. The sun tends to change color throughout the day due to scattering. As the distance for the light to travel gets greater, the atmospheric particles have more of an effect on the light. More of the yellow frequencies get scattered causing much more reddish-orange colors.
 * Why is the sky blue and why are sunsets red?**

__**Lesson 1a-d (Method 4)**__
We are able to see because light from an object moves through space and reaches our eyes. Once there, signals are sent to the brain which deciphers these signals and tells us what we are seeing. Without light, there would be no sight. Luminous objects- objects that generate their own light (sun) Illuminated objects- objects that are capable of reflecting light to our eyes (moon)
 * What is the role of light to sight?**

Line of sight- directing of our sight in a specific direction In order to view an object, you must sight along a line at that object; and when you do light will come from that object to your eye along the line of sight. Rays of light diverge off objects in a variety of directions however, your eyes only see a small portion of those rays. Incident ray- the ray of light that comes from an object and travels toward a mirror. Reflected ray- the ray of light that travels from the mirror towards your eye. For all plane mirrors, the object distance (distance from object to mirror) is equal to the image distance (distance from image to mirror).
 * How do you find the line of sight?**

The law states that the angle of incidence will always be equal to the angle of reflection when dealing with a plane mirror. A diagram is shown below: I = incident ray R = reflected ray theta i = angle of incidence theta r = angle of reflection N = normal line to the mirror (perpendicular to mirror)
 * What is the law of reflection?**

Specular reflection- reflection off of smooth surfaces such as plane mirrors or calm bodies of water Diffuse reflection- reflection off of rough surfaces such as clothing, asphalt, and paper
 * What is the difference between specular and diffuse reflection?**

The incident rays follow the law of reflection so when they hit the rough surface, each ray hits a surface with a different orientation. This means that each ray has a different angle of incidence, which as a result, means that each has a different angle of reflection. This causes the light to be diffused.
 * Why does a rough surface diffuse a beam of light?**

**__Lesson 2a-f (Method 4)__**
In order to see the image of an object in a mirror, you must sight at the image; when you sight at the image, light will come to your eye along that line of sight. The image location is located behind the plane mirror where all the light appears to diverge from. No matter where you look at the mirror from, the image will always appear to be in the same spot.
 * Why is an image formed?**

Virtual image- image formed in location where light does not actually reach Upright Located behind the mirror at the same distance as the object's distance from the mirror The image is the same size. The image is also laterally inverted.
 * What are some image characteristics?**

It is a diagram that traces the path that light takes in order for a person to view a point on the image of an object. On the diagram, rays (lines with arrows) are drawn for the incident ray and the reflected ray.
 * What is a ray diagram?**


 * What portion of a mirror is required?**

A right angle mirror produces three images, as seen below: Diagrams A and B show primary images, while Diagram C shows a secondary image. The ray diagram below shows how the images are formed:
 * How does a right angle mirror work?**

Here are some examples of other mirror systems:
 * What are some other multiple mirror systems?**

__**Lesson 3a-g (Method 4)**__
Spherical mirrors are those with a spherical shape. The two types of spherical mirrors are concave and convex mirrors. The principal axis is the imaginary line that attaches to the center of the mirror. The center of curvature is the center of the sphere from which the mirror was cut. The vertex is the point where the mirror meets the principal axis. The focal point is midway between the vertex and the center of curvature. Radius of curvature is known as the distance between the vertex and the center of curvature. The distance from the mirror to the focal point if the focal length.
 * What is the anatomy of a curved mirror?**

The normal on the point of incidence goes through the center of curvature. After the normal is drawn, the angle of incidence can be measured and the reflected ray can then be drawn.
 * How does the law of reflection work with concave mirrors?**

Any incident ray traveling parallel to the principal axis on its way to the mirror will pass through the focal point after reflection. Any incident ray passing through the focal point on the way to the mirror will travel parallel to the principal axis upon reflection. These two rules help to determine the image location of an object after reflection off a concave mirror.
 * What are the two rules of reflection for concave mirrors?**

You must use the facts from the anatomy of a curved mirror and the two rules of reflection in order to draw a ray diagram for a concave mirror.
 * What does a ray diagram look like for concave mirrors?**

The location (relative location), orientation (upright/inverted), size (enlarged/reduced/same size) and type (real/virtual) of a image depends on where the object is located. Beyond C: image in between C and F, inverted, reduced in size, real image At C: image will also be at C, inverted, same size, real image Between C and F: image will be beyond C, inverted, enlarged, real At F: no image is formed In front of F: image will be located on the opposite of the mirror, upright, enlarged, virtual
 * What are the image characteristics for concave mirrors?**

Mirror equation This diagram shows the meanings behind the variables.
 * What are the mirror and magnification equations?**

Magnification equation The magnification equation relates the ratio of the image distance and object distance to the ratio of the image height (hi) and object height (ho).

All spherical mirrors have an aberration (a departure from the expected or proper course). These aberrations are most noticeable for rays of light that strike the outer edges of the spherical mirror. The images fail to focus at the same point therefore the images from a spherical mirror are blurry. If you use a parabolic mirror rather than a spherical mirror, the aberrations will disappear and the mages will be clear and sharp.
 * What is a spherical aberration?**

__**Lesson 4a-d (Method 4)**__
A convex mirror is formed from the outside of a sphere. The center of curvature and focal point for convex mirrors are located on the opposite side of the object. The light originating from the same point will diverge rather than converge. All eyes observe the image in the same location behind the mirror. All viewers must sight the image along the reflected ray in order to see the image. The image in the mirror is a virtual image.
 * What is the anatomy of a convex mirror?**

Any incident ray traveling parallel to principal axis on its way to a convex mirror will reflect in a manner that its extension (the imaginary line that extends from the reflected ray through the mirror) will pass through the focal point. Any incident ray traveling towards a convex mirror such that its extension passes through the focal point will reflect and travel parallel to the principal axis.
 * What are the two rules of reflection for convex mirrors?**

You must you the laws of reflection and the anatomy in order to draw accurate ray diagrams. An example is shown above in the picture.
 * How do you draw a ray diagram for a convex mirror?**

Unlike concave mirrors, all objects share the same image characteristics for convex mirrors. The image is located behind the mirror, it is a virtual image, it is upright, and it is reduced in size. This diagram shows the object locations and the corresponding image locations:
 * What are the image characteristics for convex mirrors?**

The equations are the same as the equations for concave mirrors. Mirror equation This diagram shows the meanings behind the variables.
 * What are the mirror and magnification equations for convex mirrors?**

Magnification equation The magnification equation relates the ratio of the image distance and object distance to the ratio of the image height (hi) and object height (ho).

__**Lesson 1a-d: Refraction at a Boundary (Method 4)**__
When the incident pulse reaches the boundary between the thin and thick rope: -Some of the energy bounces back to the thin end of the rope, called reflected pulse. -Some of the energy continues through the thick rope, called the transmitted pulse.
 * How does boundary behavior work for waves on a rope?**

When a light wave hits a glass boundary, a portion is reflected and a portion goes through the glass. In addition to the wavelength and speed decreases as it passes through the boundary, the rays of light also change direction. This bending is known as refraction.
 * How do light waves refract?**

The direction of light is represented by an arrowhead that is perpendicular to the wavefronts of the light ray.
 * What is the ray model of light?**

It is the directing of our sight in a specific direction.
 * What is the line of sight?**

A change of speed at the boundary causes a change in direction. The two conditions that must occur in order to change the direction are: - the students must change speed when crossing the boundary. - students must approach the boundary at angle angle other than 90 degrees. Refraction will not occur if the angle is perpendicular.
 * What is the cause of refraction?**

When an electromagnetic wave is traveling through a medium, its speed is dependent on the optical density of the medium. The optical density relates to the sluggish tendency of the atoms of a material to maintain the absorbed energy of an electromagnetic wave in the form of vibrating electrons before reemitting it as a new electromagnetic disturbance.
 * What is optical density?**

They are the numerical values that indicate the number of times slower that a light wave would be in a material than in a vacuum. It is represented by the symbol, n. The equation is as follows: This is a table of a few index of refraction values:
 * What is the index of refraction value?**

The direction depends on whether the light is moving from a high dense medium to low, or low to high. If moving from high to low, the reflected ray will bend toward the normal line, as seen below.
 * How is the direction of bending determined?**

If moving from low to high, the reflected ray will bend away from the normal line, as seen below.

Light will always take the path that requires the least amount of time to get from one point to another.
 * What is the least time principle?**

__**Lesson 2a-d (Method 4)**__
Refraction is the bending of the path of a light wave as it passes across the boundary separating two media. The two rules that light follows as it refracts is SFA and FST, which were described in Lesson 1. The diagram below shows a ray of light refracting: Theta i: angle of incidence Theta r: angle of refraction The amount of refraction depends on how different the indices of refraction of the two media involved. The bigger the difference in the values, the bigger the refraction.
 * What are the rules for angles of refraction?**

It is the relationship between the angles of incidence and refraction and the indices of refraction of the two media. The equation and its variables are described below.
 * What is Snell's Law?**

**__Lesson 3a-c (Method 4)__**
It is the reflection of the total amount of incident light at the boundary between two media. The two requirements for TIR to occur are: - the light is in the more dense medium and approaching the less dense medium. - the angle of incidence is greater than the so-called critical angle. In order to find this critical angle, you must use Snell's Law and plug in 90 degrees for the angle of refraction.
 * What is total internal reflection?**

It is the largest angle of incidence for which refraction can still occur. The formula for the critical angle is shown below:
 * What is the critical angle?**

**__Lesson 4a-c (Method 4)__**
The separation of visible light into its different colors is called dispersion. Each color has a different wave frequency and different wave frequencies will bend different amounts depending on the optical density (index of refraction).
 * How is light dispersed by a prism?**

It is the amount of overall refraction caused by the passage of a light ray through a prism. The angle of deviation is the angle made between the incident ray of light entering the first face of the prism and the refracted ray that emerges from the second face of the prism. The colors with shorter wavelengths will have a larger angle of deviation, as shown below.
 * What is the angle of deviation?**

In order to see a rainbow, your back must be to the sun and you must being viewing the water droplets in the air at about a 40 degree angle. Each droplet acts as a tiny prism that disperses the light and reflects it back towards you. The way the colors reflect back towards you is determined by the wavelengths of the specific colors. A rainbow is really a full, complete circle, however, the ground blocks the other half.
 * How is a rainbow formed?**

It is an optical illusion that creates the illusion of water and results from the refraction of light through a non-uniform medium.
 * What is a mirage?**

**__Lesson 5a-f (Method 4)__**
It is a carefully ground or molded piece of transparent material that refracts light rays in such as way as to form an image. There are two types of lenses. A converging lens is a lens that converges rays of light that are traveling parallel to its principal axis. A diverging lens is a lens that diverges rays of light that are traveling parallel to its principal axis. A picture of these two lenses is shown below": The diagram below shows the anatomy of a convex lens: "F" is the focal point. "2F" is just an imaginary point on the principal axis.
 * What is a lens?**

Converging: - Any incident ray traveling parallel to the principal axis of a converging lens will refract through the lens and travel through the focal point on the opposite side of the lens. - Any incident ray traveling through the focal point on the way to the lens will refract through the lens and travel parallel to the principal axis.
 * What are the rules of refraction for converging and diverging lenses?**

Diverging: - Any incident ray traveling parallel to the principal axis of a diverging lens will refract through the lens and travel //in line with//the focal point (i.e., in a direction such that its extension will pass through the focal point). - Any incident ray traveling towards the focal point on the way to the lens will refract through the lens and travel parallel to the principal axis.

In addition, there is one rule of refraction that is the same for both converging and diverging lenses: - An incident ray that passes through the center of the lens will in affect continue in the same direction that it had when it entered the lens.


 * What does the ray diagram look like for a converging lens and what are the image characteristics for various object locations?**

Object beyond 2F: - Image located between F and 2F on other side of lens - Inverted - Reduced - Real

Object at 2F: - Image located at 2F point on other side of lens - Inverted - Same size - Real

Object between 2F and F: - Image located beyond 2F point on other side of lens - Inverted - Enlarged - Real

Object at F: - No image formed

Object between F and Vertex: - Image located on same side as object and farther from the lens than the object - Upright - Enlarged - Virtual


 * What does the ray diagram look like for a converging lens and what are the image characteristics for various object locations?**

No matter where the object is, the image characteristics will always be the same: - Image located on the object's side of the lens - Reduced - Upright - Virtual

You need the lens equation:
 * What equations are needed to solve lens problems?**

and the magnification equation:


 * What are the sign conventions for lenses?**

**__Lesson 6a-e (Method 4)__**

 * What are some major parts of the eye?**

Due to the fact that the cornea has a bulging shape, it works with the lens and ciliary muscles to form an image that is reduced in size and inverted. This image shows up on the retina. This process is called accommodation. The brain knows that the object is right side up so it automatically switches the image back.
 * How does the eye allow us to see?**

It is the eye's ability to adjust its focal length in order to see objects at various distances. Because the image distance is constant, the eye must adjust itself so the focal length can change in order to get a focuses image that shows up in the fovea centralis, the region on the retina that is the optical location. The ciliary muscles work to change the shape of the lens in order to change the focal length. The maximum variation in the power of the eye is called the Power of Accommodation. As a person grows older, their Power of Accommodation decreases which results in poor sight up close and far away.
 * What makes accommodation so special?**

It is the inability of the eye to focus on objects at a close distance. People with this issue can see at a distance without trouble, however, it is objects up close that are an issue. The ciliary muscles no longer have the ability to contract the lens enough. The correction for this problem is with the help of a converging lens, which decreases the image size prior to getting to the eye.
 * What is farsightedness and what is its correction?**

It is the inability of the eye to focus on objects at a far distance. This usually occurs in younger people who have a cornea that is bulging too much, which causes the image to focus prior to getting to the retina. The cure for this problem is to use a diverging lens, which will help to allow the person to see a focused image.
 * What is nearsightedness and what is its correction?**