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Shedding Light on. Wave-Particle Duality. Nicole Ozdowski Samantha Candalor Andrew Lingenfelter Fernando Marill-Tabares. An Investigation of Light. Wave Theory of Light. Aristotle (384–322 BC) [4th century BC]. Pythagoras (570-495 BC) [6th century BC]. 17th Century:.
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Shedding Light on Wave-Particle Duality Nicole Ozdowski Samantha Candalor Andrew Lingenfelter Fernando Marill-Tabares An Investigation of Light
Wave Theory of Light Aristotle (384–322 BC) [4th century BC] Pythagoras (570-495 BC) [6th century BC]
17th Century: Christiaan Huygens (1629-1695) Isaac Newton (1642-1727)
19th Century: Thomas Young (1773-1829) Augustin Fresnel (1788-1827)
1861: • Proved that Electricity and Magnetism were expressions of the same thing. • Found the equality between an electromagnetic wave and light James Clerk Maxwell (1831-1879)
Einstein’s Photoelectric Effect Heinrich Hertz (1857-1894) Albert Einstein (1879-1955)
Quantum Mechanics: Wave-Particle Duality Wave? Particle? Both?
Interference Constructive Interference Destructive Interference
Young’s Double Slit Experiment Δx = λD/a Δxr = 0.47cm Δxg = 0.40cm
Setting Up the Experiment Light Sensor and Single Slit Laser and Double Slit
Results Δxr,th = 0.47cm Δxr,exp = 0.467cm %error = 0.64% Δxg,th = 0.40cm Δxg,exp = 0.413cm %error = 3.25% Conclusion: Light acts as a wave.
Setting Up the Experiment Mercury Lamp and Detector Amplifier and Meters
Results • V=(h/e)*f • Slope is equal to h/e • h/e = -4.136*10-15 Js/C • Our slope = -2.317*10-15Js/C The closeness of the two values confirms the photoelectric effect. Conclusion: Light acts as a particle.
Single Photon Detection Double Slit Experiment • Repeat the double slit experiment • Count photons instead of measuring intensity • If light is a wave then detector won’t count • If light is a particle, there won’t be an interference pattern.
Experimental Setup Laser and Double Slit Photomultiplier tube
Results Theoretical ΔX: 0.2626 cm Experimental ΔX: 0.2622 cm Error: 0.15% Counts of Single Photons produce an Interference Pattern. Conclusion: Light acts as a wave and a particle.
Conclusion Is light a wave? The double slit experiment says yes. Is light a particle? The photoelectric experiment says yes. Is light both? The photon detection experiment says yes. Therefore…
Quantum Mechanics: Wave-Particle Duality Light as a Particle: • Well defined position • Wavelength is unclear • Can slam into particles Light as a Wave: • Well defined momentum and wavelength • Position is spread out and unclear • Can interfere and diffract as a wave would
Acknowledgments Dr. Luokkala - PGSS Director Patrick Diggins and Zach McDargh - Project Leaders Patty Yoritomo - Project TA Corporate and Private Sponsors PGSS Alumni Association PGSS Campaign
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