EssaysForStudent.com - Free Essays, Term Papers & Book Notes
Search

Ray Optics, Light Intensity, and Polarization

Page 1 of 12

Title Section

14th November 2017                        Lab Section 020_4177                        TA: Nate Orndorf

Alex Sabitsch

Partners: Hatice Ozdemir,

Ray Optics, Light Intensity, and Polarization

Abstract

        This lab experiment had multiple purposes. The first was to determine the focal length of a lens or spherical concave mirror. The second was to investigate the location, orientation, and magnification of images. The third was to measure the variation in light intensity. Finally, the fourth was to explore properties of polarized light. For this experiment, the materials that the group used were converging lenses, concave spherical mirrors, meter stick, long ruler, light source, index card, holders for light source, index card, and lenses, PASCO software, light sensor, and polarized sheets. For each part of the lab the group had to preform various tasks. For the first two parts, we had to determine the object distance and object distance for multiple runs. For each of the three trials the group found the focal length to be about 16 cm with a magnification between -.675 and -1.48. For the third part, we had to graph the light intensity as a function of distance and finally, for the last part we had to find other sources of polarized light within the lab. We concluded that the computer screen emitted polarized light.

Introduction

        The first two purposes of this experiment were to find the focal length of a lens and to investigate the location, orientation, and magnification of images using a spherical concave mirror. Thin lenses and small spherical mirrors share one similar characteristic which is a focal length (f). The focal length is defined as the image distance of an object that is positioned very far away. Incoming light rays from the object are always parallel which indicates that the object is very far away from the light source. As seen in figure 2, the point C marks the center of the curvature of the mirror. The distance from C to any point on the mirror or lens is called the radius of curvature which happens to be twice the focal length. The object distance (do) and image distance (di) are the distance between the lens or mirror and the object and the image. These distances can be related back to the lens equation which is:

  1. [pic 1]

The magnification (m) can be defined by the ratio of the height of the image (h) and the object height (ho). Magnification is also related to the ratio of the object and image distances as seen below:

  1. [pic 2]

Here the image height (hi)is negative when the image is upside down where the image distance for a lens is positive when the image is on the side of the lens that is opposite to the incoming light. This makes the focal length of a converging lens positive. Equations 1 and 2 also apply for spherical mirrors. The only difference is that with mirrors, the image distance is taken to be positive when the image is on the same side of the mirror as the object.

The final two purposes of this lab were to measure variations of light intensity, and to explore properties of polarized light. Light waves are transverse waves much live ocean waves or waves in a stretched string. Light waves are displaced from the equilibrium position by the electric field. When a light wave is traveling along an axis, its displacement is not in the same axis, rather it is in an axis perpendicular to the axis its traveling in. The direction of the electric field is called the direction of polarization of light. This is light from a source is unpolarized which means that the light is a mixture of light waves that have been polarized in various directions.

Light intensity is important when talking about light polarization. Light intensity is the average amount of energy that passes through a unit area in time which has the units of watt/m^2. For this lab, the intensity of light decreases with the square of the distance from the source, or as seen by the equation below:

  1. [pic 3]

Here r is the distance from the center of the light source, in our case a bulb. C is a constant with units of watt. If background light is present it adds a constant to the intensity. In our case we do not have to worry about this constant.

A polarizer sheet allows light from a polarization to pass through while blocking all the other directions. When unpolarized light tries to pass through the sheet only the component parallel to the transmission axis can pass through. When polarized light encounters a polarizer the amount of light that passes through I dependent on the angle between the transmission axis and the polarization direction of the light. The intensity of the light that passes through the polarizer can be expressed by the equation below:

Download as (for upgraded members)
txt
pdf
Citation Generator

(2017, 11). Ray Optics, Light Intensity, and Polarization. EssaysForStudent.com. Retrieved 11, 2017, from https://www.essaysforstudent.com/English/Ray-Optics-Light-Intensity-and-Polarization/107906.html

"Ray Optics, Light Intensity, and Polarization" EssaysForStudent.com. 11 2017. 2017. 11 2017 <https://www.essaysforstudent.com/English/Ray-Optics-Light-Intensity-and-Polarization/107906.html>.

"Ray Optics, Light Intensity, and Polarization." EssaysForStudent.com. EssaysForStudent.com, 11 2017. Web. 11 2017. <https://www.essaysforstudent.com/English/Ray-Optics-Light-Intensity-and-Polarization/107906.html>.

"Ray Optics, Light Intensity, and Polarization." EssaysForStudent.com. 11, 2017. Accessed 11, 2017. https://www.essaysforstudent.com/English/Ray-Optics-Light-Intensity-and-Polarization/107906.html.