Polarization and Interference

Polarization and Interference - Michael Lin Partners Josh...

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Michael Lin Tuesday Section Partners: Josh Narciso, Bryant Rolfe Due Date: 3/27/07 Polarization and Interference Michael Lin The objective of this experiment was to investigate two concepts of wave mechanics: polarization and interference. Polarization was observed by measuring the intensity of light and its variation with the angle of the polarizer. Interference was observed by measuring the locations of the intensity maxima. The polarization experiment showed good agreement with Malus’ law and expected experimental results. In the double slit diffraction pattern experiment, the measured wavelength of the laser was 527.27 +/- 22.32 nm, which was 16.60% off from the actual wavelength of 632.8 nm. INTRODUCTION Polarization occurs in transverse waves, waves whose vibrations are perpendicular the direction of its propagation (such as light). More specifically, it describes the axis in which the wave oscillates; in three dimensional space, the angle or direction of polarization can be any angle on the plane perpendicular to the direction of wave oscillation. Unpolarized waves can oscillate along more than one axis within this plane, whereas polarized waves only oscillate on one axis within this plane. For light, the state of polarization usually refers to the axis of vibration for the electric fields (light is electromagnetic radiation, also consisting of magnetic fields). Usually the light produced from a light source is unpolarized, and the electric field vibrations are in random directions on the plane perpendicular to the direction of wave motion. Unpolarized light can be polarized by passing the light through a polarizing filter. When the light encounters the filter, the component of the electric field that is perpendicular to the molecular chains composing of the filter is transmitted (also known as the transmission axis), while the component parallel to the chains is absorbed into the filter. If the light is then passed through a second filter (analyzer), whose transmission axis is at an angle with respect to the first filter (polarizer), the polarization state of the light can be analyzed. Varying these angles will allow a different intensity of light to pass through and be read by a photometer, and then be used to construct a relationship between the intensity of light and the angle between the two filters, also known as Malus’ law. When two waves of light collide, the wave that results is simply the sum of the two waves. If they collide when both are completely in phase, then the two will sum up perfectly and create totally constructive interference. If they collide when the two waves are completely out of phase, then the two will perfectly cancel and create totally destructive interference. Interference of waves can also occur when the waves are at other positions in their oscillatory cycle, and this determines the amount of constructive or destructive interference in the resulting wave. When visible light interferes, the result of the superimposition of the light waves is either an increase in the intensity of light (constructive
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This note was uploaded on 03/05/2008 for the course PHYS 1494 taught by Professor Carlo during the Spring '08 term at Columbia.

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Polarization and Interference - Michael Lin Partners Josh...

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