Ch24_SolomonE

toc = = =Chapter 24 Guiding Questions=

a. __Newton__- refraction of light; prism could separate light into a spectrum of colors b. __Huygens__- light was made up of waves vibrating up and down; known as "Huygens' Principle" c. __Grimaldi-__ observed diffraction of light d. __Young-__ interference of light waves by shining light through a screen e. __Maxwell-__ magnetism, electricity, and light are all part of electromagnetism f. __Hertz-__ discovered radio waves; frequency of waves named after him g. __Einstein-__ light composed of photons, which each have energy
 * 1. Identify the contributions from each of the following scientists to the study and the nature of light.**

a. __Galileo-__ light travels faster than sound b. __Roemer-__ quantitatively measured speed of light c. __Fizeau-__ light travels at 3.13 * 10^8 m/s
 * 2. Measuring the speed of light was challenging. Describe the results of the experiments by each of the following scientists.**

a. Electromagnetic waves require no medium, and mechanical waves do b. Electromagnetic waves are 3 dimensional, mechanical waves are 2 dimensional
 * 3. What are the 2 biggest differences between an electromagnetic wave and a mechanical wave?**

a. visible light is in middle b. radio waves -- microwaves -- infrared rays -- visible light -- ultraviolet rays -- x-rays -- gamma rays c. wavelength decreases left-right d. frequency increases from left-right e. electromagnetic spectrum -- ROYGBIV
 * 4. Describe the EM spectrum.**

a. light waves have frequency; able to compare observed to actual w/Doppler effect
 * 5. Apply the Doppler affect to light.**

a. conversion of unpolarized light to polarized light b. measurement of alignment of electromagnetic field
 * 6. What is polarization?**

a. intensity produced when a polarizer and analyzer are placed in front of incident beam equals original intensity * cosine^2 of angle between the two filters.
 * 7. Describe Malus' Law.**

a. __Polarizer__- always first filter; removes 50% of light's intensity b. __Analyzer__- always second filter; amount of intensity it removes is dependent upon the angle between the first and second filter
 * 8. Contrast the polarizer and the analyzer.**

a. light reflecting off of shiny surfaces b. light entering the earth's atmosphere
 * 9. When does polarization occur in nature?**

a. What is the relative orientation of the transmission axes of the filters when maximum intensity is transmitted? i. 0 degrees b. What should the intensity of the light beam be in this orientation? i. S= So(cos^2(theta)) S=820/2 S= 410 W/m^2 c. What is the relative orientation of the transmission axes of the filters when minimum intensity is trasmitted? 90 degrees d. What will be the intensity of the light transmitted by the filters when the intensity is at a minimum i. 0 W/m^2 e. If a third polarizer is inserted between the first two polarizers (as oriented in c) and the angle of this third polarizer is rotated until the angle between it and the first polarizer is 25 degrees. What will be the intensity transmitted by all three? i. S=So(cos^2(theta)) S= 510 cos^2(25) S= 337 W/m^2
 * 10. Two polarizing filters are placed in the path of a beam of light with an intensity measured to be 820. W/m^2. The analyzer is then rotated**
 * until the intensity is at a maximum. Assuming that the two filters are perfect:**

S= 337cos^2(65) S= 60 W/m^2

=Chapter 25 Guiding Questions=

a. Wave fronts- surfaces that all emit light through the same medium b. Rays- single beams of light
 * 1. Distinguish between wave fronts and rays.**

a. Specular reflection- occurs off of smooth surfaces b. Diffuse reflection- occurs off of rough surfaces
 * 2. Distinguish between specular and diffuse reflection.**

a. Reflected angle of light = incident angle of light
 * 3. What is the law of reflection?**


 * 4. Draw a diagram identify rays and angles.**

a. n1sin(theta)1=n2sin(theta)2 1sin30=1.65sin(theta)2 theta2= 17.64 degrees
 * 5. A ray of light in air is incident on an air-to-glass boundary at an angle of 30 degrees with the normal. If the index of refraction of glass is 1.65, what is the angle of the ray reflected off the glass surface with respect to the normal?**

location, orientation, size, type
 * 6. List the 4 ways we describe images. In other words what are the characteristics of images?**

a. Real images- occur when light rays intersect; in front of mirror b. Virtual images- occur when light rays do not actually intersect; image behind the mirror
 * 7. Distinguish between real and virtual images.**

a. size ratio of image to object
 * 8. What is magnification?**

Behind mirror, Upright, Same Size, Virtual
 * 9. What are the image characteristics of an object viewed in a plane mirror?**

a. vertex
 * 10. What is the reference position for all distances measurements on mirror or lens problems?**

a. __Concave Mirrors__- diverging, positive focal length, spread light, produce real virtual images based on location of the object b. __Convex Mirrors__- converging, negative focal length, focus light, produce virtual images
 * 11. What is the sign convention for images in mirrors or lenses?**
 * 12. Distinguish between concave and convex mirrors.**

a. __Principal Axis__- goes through the center of the mirror; has C and F along it b. __Focal Point__- Point where all the rays reflect to off mirror c. __Focal Length__- Distance between mirror and focal point d. __Center of Curvature__- radius of a spherical mirror e. __Radius of Curvature__- two * focal length; distance from center of curvature to mirror
 * 13. Identify the following terms:**

reduced, virtual, upright
 * 15. What are the image characteristics of an object viewed in a convex mirror?**

No image
 * 16. What image will be produced when the object viewed is located at the focal point of the mirror?**

Rear-view mirrors are convex mirrors to focus images so a wider range of images can be seen Makeup mirrors are concave produce magnified images so makeup can be applied carefully = = =Pre-Lab: What is the relationship between intensity and angle of polarization?=
 * 17. What are several applications of mirrors (besides looking at your own gorgeous features)?**

1. The objective is stated in the title. What is your hypothesis? (Attempt to answer the question, to the best of your knowledge.)

The angle of polarization is inversely related to intensity from 0 degrees to 90 degrees. As the angle goes from 90 towards 180 degrees, the intensity will increase (direct relationship). This will be the same from 180-270 and 270-360 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.) . Based upon this equation, when theta equals 0 and 180, the intensity will be at its greatest. Also, when theta equals 90, cos^2(theta) equals zero. Therefore, the hypothesis that I had provided above about the relationships between intensity and angle of polarization would stand to be accurate.

3. How do you think you might test this hypothesis? (What might you measure and how?) I could use two polarizing lenses (first lens to block half of the light wave & second lens to block a portion of the other light wave's plane). I could use a sensor (or just look manually) to detect the amount of light passing through at different angles between the lenses of the second lens relative to the other amounts of light passing through at another angle.

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? The maximum intensity is at 0 degrees between the filters. The minimum intensity is 90 degrees between the filters.

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

As predicted, the intensity-angle between polarizing filters relationship is inversely proportional between 0 and 90 degrees.

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