Polarization of Light Polarization of Light Presented by Beili Wang SC 442 Honors class 2001, Dr. Roman Kezerashvili

Objective 1. Study the polarization of light 2. Study two phenomena of light: Absorption Reflection 3. Verify Brewster’s law and Malus’s law

Theory 1. Two properties of light a. The wave theory of light The light is a transverse electromagnetic wave with the vibrating electric and magnetic fields, which are perpendicular to each other and to the direction of propagation of light. b. Polarization Polarization is a property of transverse wave related to the directions in which vibration occur.

Part I. Polarization (a)Transverse wave on the string polarized in the y-direction (b)Transverse wave polarized in the z-direction. (c)The vertical slit passes component polarized in the y-direction and blocks those in the z-direction acting as a Polaroid. y y y x z x z x z (a) (b) (c)

Polarizer The light passes through a polarizer that has the effect of polarization. Axis of Polarizer Incident unploarized light Linearly polarized light Polarizer

Analysis for Part I Crossed Arrow Target holder Holders with polarizer and analyzer Light source When light is sent through the polarizers, electric field components parallel to the polarizing direction is transmitted; while components perpendicular to the polarizing direction are absorbed by the polarizers and disappear

Part II. Absorption θ Axis of Polarizer Direction of axis of Polarizer on the left Polarizer Axis of Analyzer Analyzer Malus’s law

Data from Part II Intensity of the light when both polarizer and analyzer are removed: i = 10 w/m^2 Intensity of the light when it passes just through the polarizer: i 1 = 4 w/m^2 Intensity of the light when it passes through the polarizer and analyzer: i 2 = 2.5 w/m^2 Ratio of intensities:i 1 /i = 0.4 Ratio of intensities: i 2 /i = 0.25 Ratio of intensities: i 1 /i 2 =1.6

Table 1 for Part II Angle θ, degrees (Cosθ)^2Intensity of light (clockwise) Intensity of light (counterclockwise) Average intensity

Graph for Part II

Part III. Reflection Normal line Unpolarized Incident ray Polarized Reflected ray Slightly polarized Refracted ray Medium 1 Medium 2 θBθB θBθB θ2θ2 90 degree

Table 2 for Part III Acrylic Cylindrical lens Brewster’s angle θB= 57 degree Index of refraction n1 =1 Index of refraction n2 = 1.50 Stander value for n2 = 1.53 %error = 2% Glass Cylindrical lens Brewster’s angle θB= 57 degree Index of refraction n1 =1 Index of refraction n2 = 1.46 Stander value for n2 = 1.52 %error = 3.95%

Conclusion In this experiment, we study the polarization of light by observing the reflection of the light and the absorption of the light. Furthermore, we verify Brewer’s law and Malus’s law for polarized light.

Questions or Comments Questions or Comments The End Thank You