### Shedding Light on Wave-Particle Duality

```Nicole Ozdowski
Samantha Candalor
Andrew Lingenfelter
Fernando Marill-Tabares
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:
James Clerk Maxwell (1831-1879)
●
Proved that Electricity and
Magnetism were
expressions of the same
thing.
●
Found the equality
between an
electromagnetic wave and
light
Einstein’s Photoelectric Effect
Heinrich Hertz (1857-1894)
Albert Einstein (1879-1955)
Quantum Mechanics:
Wave-Particle Duality
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.
The Photoelectric Experiment
The Concept
Setting Up the Experiment
Mercury Lamp and Detector
Meters
Amplifier and
Results
●
V=(h/e)*f
●
Slope is equal to h/e
●
h/e = -4.136*10-15 Js/C
●
Our slope = -2.317*1015Js/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
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
tube
Photomultiplier
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…
Light is a Wavicle.
Quantum Mechanics:
Wave-Particle Duality
Light as a Wave:
Light as a Particle:
● Well defined momentum
and wavelength
● Well defined position
and unclear
● Wavelength is unclear
● Can interfere and diffract
as a wave would
● Can slam into particles
Acknowledgments
Dr. Luokkala - PGSS Director
Patrick Diggins and Zach McDargh - Project Leaders
Patty Yoritomo - Project TA
PGSS Alumni Association
PGSS Campaign
References
http://en.wikipedia.org/wiki/Thomas_Young_(scientist)#mediaviewer/File:Thomas_Young_(scientist).jpg
http://www.physicsoftheuniverse.com/images/quantum_double_slit.jpg
http://i.stack.imgur.com/Q4brH.gif