Chapter+24

flat =Polarization Prelab=
 * 1) What is your hypothesis?
 * 2) There is a direct relationship between the intensity of the cosine squared of the angle. I know this from the equation[[image:Screen_shot_2011-12-21_at_9.32.03_AM.png]]. We will test this hypothesis using a setup with polarizers, a light sensor, and light sources. We will vary the transmittance of light in this lab.
 * 3) Read the entire labsheet through. Make a table.
 * 4) Done!
 * 5) Table is shown below
 * 6) Light is shown through a set of two polarizing filters. When is transmitted light at maximum intensity? Minimum intensity?
 * 7) When the two polarizers are parallel (angle of 0 degrees), the intensity is at a maximum.
 * 8) When the two polarizers are perpendicular (angle of 90 degrees), the intensity is at a minimum.
 * 9) What is the relationship of the intensity of transmitted light to the angle of the polarizers between 0 and 90 degrees?
 * 10) The intensity of transmitted light is inversely proportional to the angle of the polarizers between 0 and 90 degrees.
 * Percent Transmittance || Angle between Polarizers || Intensity ||

=Chapter 24 Guiding Questions=

Reflection and the Ray Model of Light Summaries
=Lesson 1: Reflection and its Importance=

There is no sight without light. Luminous objects generate their own light, while illuminated objects are capable of reflecting light to our eyes.
 * What is the role of light?**

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.
 * What is the line of sight?**

Distance from object to mirror is equal to distance from image to mirror.
 * How is light shown in a mirror?**

I - incident ray R - reflected ray N - normal line Theta i - angle of incidence Theta r - angle of reflection Angle of incidence = angle of reflection
 * What is the law of reflection?**

Specular reflection is reflection off of smooth surfaces. Diffuse reflection is reflection off of rough surfaces.
 * What is specular and diffuse reflection?**

=Lesson 2: Image Formation in Plane Mirrors=

The image location is the one location in space where it seems to every observe that the light is diverging from.
 * Why is an image formed?**

Virtual - image formed in a location where light doesn't actually reach. Upright - image is not turned upside down Same size as object - magnification is equal to one
 * What are the image characteristics in plane mirrors?**

A ray diagram traces the path that light takes in order for a person to view a point on the image of an object. 1. Image is drawn as far away to the mirror as the object is. 2. 3. 4.
 * How do you draw ray diagrams for plane mirrors?**

Al can only see Ed and Fred in the mirror. This is how to determine who can see what in a mirror.

No matter how far or close one stands to the mirror, the portion needed to view the image will remain the same. It will only change if the height is changed.
 * What portion of a mirror is required to view an image?**

A right angle mirror is a pair of plane mirrors adjoined at right angles to each other. It produces three images and the ray diagrams are shown below.
 * What are right angle mirrors?**


 * What are some other multiple mirror systems and what do they produce?**

=Lesson 3: Concave Mirrors=

Spherical Mirrors - concave and convex C - center of curvature R - radius of curvature A - vertex (where axis and mirror meet) F - focal point (midway between C and A) f - focal length (light travelling parallel to the principal axis will reflect off the mirror and hit this point)
 * What is the anatomy of a curved mirror?**

Concave mirrors produce real images and virtual images. Image location is the point where all the rays intersect on the other side of the principal axis.
 * Discuss the reflection of light and image formation for concave mirrors.**

1. Any incident ray traveling parallel to the principle axis on the way to the mirror will pass through the focal point upon reflection. 2. Any incident ray passing through the focal point on the way to the mirror will travel parallel to the principle axis upon reflection.
 * What are two rules of reflection for concave mirrors?**

1. 2. 3. 1. real, inverted, reduced in size 2. real, inverted, same size 3. real, inverted, bigger in size 4. no image is formed 5. virtual, upright, bigger in size Mirror Equation Magnification Equation f=focal length do=object distance
 * How do you make ray diagrams for concave mirrors?**
 * Explain the image characteristics for concave mirrors.**
 * What are equations used for these mirrors?**

Rays do not travel according to plan for spherical mirrors.
 * What is spherical aberration?**

=Lesson 4: Convex Mirrors=

Virtual image below 1. Any incident ray traveling parallel to the principal axis on the way to a convex mirror will reflect in such a manner that its extension will pass through the focal point. 2. 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 is the reflection and image formation for convex mirrors?**

1. 2. 3.
 * How do you make ray diagrams for convex mirrors?**

Virtual, upright, reduced in size, located behind convex mirror Same as concave mirrors!
 * What are image characteristics for convex mirrors?**
 * What are the equations for convex mirrors?**

Light and Color Summaries
=Lesson 1: How Do We Know Light is a Wave?=

Light reflects (bounce off an obstacle), refracts (pass from one medium to another), diffracts (change of direction as it passes through an opening or goes around), interferes (when two waves meet while traveling along the same medium, a phenomena occurs), and exhibits the Doppler Effect (perceived frequency) just like any other wave would.
 * What are the wavelike behaviors of light?**

Constructive interference occurs at any location along the medium where the two interfering waves have displacement in the same direction. Destructive interference occurs at any location along the medium where the two interfering waves have displacement in the opposite direction.
 * What are the two types of interference for light?**

When a wave reached the boundary between two media, a portion reflects and another portion is transmitted across the boundary and into the film. The part that is transmitted hits another boundary and is either reflected or transmitted. The two times the waves are reflected can constructively interfere if it meets the right conditions. Only certain wavelengths constructively interfere and if it is in the visible light spectrum, colors are seen.
 * What is thin film interference?**

Polarized light waves are light waves in which the vibrations occur in a single plane. To turn unpolarized light into polarized light, polarization must occur by transmission, reflection, refraction, or scattering.
 * What is polarization?**

Polaroid filters are made of special material that is capable of blocking one of the two planes of vibration of an electromagnetic wave. A Polaroid filters out one-half of the vibrations. A second filter can be used and put at a certain angle to only allow a certain percentage of light to pass through.
 * How does polarization by use of a polaroid filter work?**

Light can reflect off of nonmetallic surfaces at a certain angle which results in some degree of polarization parallel to the surface.
 * How does polarization by reflection work?**

When light passes through a medium, the path of the beam changes its direction. The refracted beam acquires some degree of polarization with perpendicular orientations.
 * How does polarization by refraction work?**

When light strikes the atom of a material, it will set the electrons of those atoms into vibration. The vibrating electrons then produce their own electromagnetic wave that is radiated outward in all directions. This newly generated wave strikes neighboring atoms, forcing their electrons into vibrations at the same original frequency and so on. This absorption and reemission of light waves causes the light to be scattered about the medium. This scattered light is partially polarized.
 * How does polarization by scattering work?**

=Lesson 2: Color and Vision=

The electromagnetic spectrum is the enormous range of frequencies of electromagnetic waves. Left - longer wavelength, lower frequency. Right - shorter wavelength, higher frequency.
 * What is the electromagnetic spectrum?**

Our eyes are sensitive to only a narrow section of the electromagnetic spectrum, known as the visible light spectrum. Red is to the left and violet is to the right (ROYGBIV). Each individual wavelength within this spectrum represents a color, so when it hits our retina, we see that color. The separation of visible light into its different colors is dispersion. White light (sunlight) is the mix of ROYGBIV wavelengths.
 * What is the visible light spectrum?**

Light that enters the eye hits the retina. The retina is lined with light sensing cells known as rods and cones. Rods are sensitive to the intensity of light. The cones sense color. When a wavelength hits a cone, a chemical reaction is activated that results in an electrical impulse being sent along nerves to the brain. Red cones, blue cones, and green cones are each used for specific ranges of light.
 * What are color cones?**

When light waves strike an object, the electrons in the atoms of the object begin vibrating. But instead of vibrating in resonance at a large amplitude, the electrons vibrate for brief periods of time with small amplitudes of vibration; then the energy is reemitted as a light wave. If the object is transparent, then the vibrations of the electrons are passed on to neighboring atoms through the bulk of the material and reemitted on the opposite side of the object. Such frequencies of light waves are said to be transmitted. If the object is opaque, then the vibrations of the electrons are not passed from atom to atom through the bulk of the material. Rather the electrons of atoms on the material's surface vibrate for short periods of time and then reemit the energy as a reflected light wave. Such frequencies of light are said to be reflected.
 * How does transmission and reflection work?**

A chemical capable of selectively absorbing one or more frequency of white light. A pigment that absorbs a single frequency is known as a pure pigment.
 * What is a pigment?**

Any three colors of light that produce white light when combined with the correct intensity are called primary colors of light. The most common set is red, green, and blue. Secondary colors of light are produced by the addition of equal intensities of two primary colors of light. If two colors are added, a new color is formed!
 * What are primary colors of light?**

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.
 * What is the process of color subtraction?**