Science > Physics > High school experiment examining particle-wave duality?
| Topic: |
Science > Physics |
| User: |
"Coyn" |
| Date: |
23 Oct 2006 12:48:48 PM |
| Object: |
High school experiment examining particle-wave duality? |
For a (relatively large) high school project, I would like to examine
particle-wave duality. I was wondering what experiments I could do to
this effect.
Ideally, I would love to look at the wave nature of the electron. An
electron ray shouldn't be too hard to come by (can I effectively get
one out of an old CRT monitor?), but is it feasable to send the
electron ray through a grating and see interference patterns? I
suppose that vacuum is needed for this, as well as something
(photographic?) which can detect the trace of the electrons on the
other side of the grating. According to de Broigle, the wavelength L
of an electron is something like mc^2=hc/L => L = hc/(mc^2) = h/mc=
2.42 pm. Is it even possible to get a grating fine enough to produce
any diffraction? Any tricks that can be used? Or any other experiments
you can suggest?
Thanks in advance
Coyn
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| User: "Sue..." |
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| Title: Re: High school experiment examining particle-wave duality? |
23 Oct 2006 01:07:57 PM |
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Coyn wrote:
For a (relatively large) high school project, I would like to examine
particle-wave duality. I was wondering what experiments I could do to
this effect.
Ideally, I would love to look at the wave nature of the electron. An
electron ray shouldn't be too hard to come by (can I effectively get
one out of an old CRT monitor?), but is it feasable to send the
electron ray through a grating and see interference patterns? I
suppose that vacuum is needed for this, as well as something
(photographic?) which can detect the trace of the electrons on the
other side of the grating. According to de Broigle, the wavelength L
of an electron is something like mc^2=3Dhc/L =3D> L =3D hc/(mc^2) =3D h/m=
c=3D
2.42 pm. Is it even possible to get a grating fine enough to produce
any diffraction? Any tricks that can be used? Or any other experiments
you can suggest?
Thanks in advance
Coyn
<< We believe that we carried out the first experiment in which the
build-up process of an interference pattern from single-electron events
could be seen in real time as in Feynman's famous double-slit
Gedanken experiment under the condition, we emphasize, that
there was no chance of finding two or more electrons in the
apparatus. >>
--Akira Tonomura
Hitachi Advanced Research Laboratory, Saitama, Japan
http://physicsweb.org/articles/world/15/9/1
<< in 1961 Claus J=F6nsson of T=FCbingen, who had been one of
M=F6llenstedt's students, finally performed an actual double-slit
experiment with electrons for the first time (Zeitschrift f=FCr
Physik 161 454). >>
http://physicsweb.org/articles/world/15/9/1
http://www.hqrd.hitachi.co.jp/em/doubleslit.html
<<Now, does not the prize to Einstein imply
that the Academy recognised the particle
nature of light? The Nobel Committee says
that Einstein had found that the energy exchange
between matter and ether occurs by atoms emitting
or absorbing a quantum of energy,hv .
As a consequence of the new concept of light quanta
(in modern terminology photons) Einstein proposed the
law that an electron emitted from a substance by
monochromatic light with the frequency has to have
a maximum energy of E=3Dhv-p, where p is the energy needed to
remove the electron from the substance. Robert Andrews
Millikan carried out a series of measurements over a
period of 10 years, finally confirming the validity of this
law in 1916 with great accuracy. Millikan had, however,
found the idea of light quanta to be unfamiliar and strange.
The Nobel Committee avoids committing itself to the
particle concept. Light-quanta or with modern terminology,
photons, were explicitly mentioned in the reports on
which the prize decision rested only in connection with
emission and absorption processes. The Committee says
that the most important application of Einstein's photoelectric
law and also its most convincing confirmation has come from
the use Bohr made of it in his theory of atoms, which explains
a vast amount of spectroscopic data. >>
http://nobelprize.org/physics/articles/ekspong/index.html
Sue...
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| User: "PD" |
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| Title: Re: High school experiment examining particle-wave duality? |
23 Oct 2006 02:35:13 PM |
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Coyn wrote:
For a (relatively large) high school project, I would like to examine
particle-wave duality. I was wondering what experiments I could do to
this effect.
Ideally, I would love to look at the wave nature of the electron. An
electron ray shouldn't be too hard to come by (can I effectively get
one out of an old CRT monitor?), but is it feasable to send the
electron ray through a grating and see interference patterns? I
suppose that vacuum is needed for this, as well as something
(photographic?) which can detect the trace of the electrons on the
other side of the grating. According to de Broigle, the wavelength L
of an electron is something like mc^2=hc/L => L = hc/(mc^2) = h/mc=
2.42 pm. Is it even possible to get a grating fine enough to produce
any diffraction? Any tricks that can be used? Or any other experiments
you can suggest?
Thanks in advance
Coyn
Electrons are tough, because the wavelengths are typically very short.
Light is easier.
Here you can use Young's disk experiment (bright spot in the middle,
counter to particle model) for the wave picture, and the photoelectric
effect (independence of ejected electron KE from intensity of incident
light, and other things) for the particle picture.
PD
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