15 Waves 6 - E0 E The magnitude of the proper component of...

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In an unpolarized wave, the angle is changing randomly. Therefore, after passing through a polarizer the average intensity is z 0 E E transmission axis cos 0 E E The magnitude of the proper component of the electric field: Intensity of the wave is proportional to the square of the amplitude 2 ~ E S 2 0 2 0 2 0 cos / S E E S S Law of Malus 2 / cos 0 2 0 S S S The light gets polarized, but we lose 1/2 of its intensity. ..
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0 cos If the axis of a polarizer is set at = 90° to the axis of polarization A system of two crossed polarizers never lets any light through. Whatever passes through the first one is blocked by the second. no light is passing through!
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What happens to the intensity, S, and the direction of polarization of unpolarized light upon passing trough three polarizers shown here? S 1 S 2 S = S 3 2 / 0 1 S S 25 cos 2 1 2 S S 45 cos ) 25 70 ( cos 2 2 2 2 3 S S S 0 2 2 0 3 205 . 0 45 cos 25 cos 2 / 1 S S S Without the second polarizer 0 2 0 3 058 . 0 70 cos 2 / 1 S S S E http://www.colorado.edu/physics/PhysicsInitiative/Physics2000/applets/lens.html
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Electromagnetic Waves Produced by an Antenna • When a charged particle undergoes an acceleration, it radiates energy – If currents in an AC circuit change rapidly, some energy is lost in the form of EM waves – EM waves are radiated by any circuit carrying alternating current • An alternating voltage applied to the wires of an antenna forces the electric charge in the antenna to oscillate
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EM Waves by an Antenna • Two rods are connected to an ac source, charges oscillate between the rods (a) • As oscillations continue, the rods become less charged, the field near the charges decreases and the field produced at t = 0 moves away from the rod (b) • The charges and field reverse (c) • The oscillations continue (d)
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15 Waves 6 - E0 E The magnitude of the proper component of...

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