TSR George
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#1
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The diagram shows a diffraction pattern.
Image
(a) Explain what is meant by diffraction.
The spreading of wave-fronts as a wave passes through a gap or around an obstacle.
(b) The diffraction pattern is produced by electrons passing through a thin sheet of graphite.
(i) State what this suggests about the behaviour of electrons.
They are also acting as waves
(ii) Suggest why substantial diffraction occurs.
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GrimlyFish
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Diffraction is more prominent when the wavelength of the wave is similar to the aperture it passes through. What can you conclude from that?
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LogicGoat
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Basically,
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So what can you say about the wavelength of the electrons compared to the gaps between the atoms?
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natninja
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The wavelength is of a similar size to the gap?

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note how there are only two rings, this is because there are only two planes within the graphite structure that diffract the electrons and through simple geometry and the Bragg scattering equation it is possible to use the measurements to find the bond length in graphite
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LogicGoat
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(Original post by natninja)
note how there are only two rings
but there's 4?
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yepyepyep
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(Original post by LogicGoat)
but there's 4?
I was thinking this too.
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natninja
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(Original post by LogicGoat)
but there's 4?
In which case it isn't through a thin graphite sheet as it says in the question...
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GrimlyFish
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(Original post by natninja)
The wavelength is of a similar size to the gap?

Better phrasing would be "The wavelength of the electron is similar to the distance between atoms" or something along those lines, some people are pick about the answer :/
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natninja
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(Original post by GrimlyFish)
Better phrasing would be "The wavelength of the electron is similar to the distance between atoms" or something along those lines, some people are pick about the answer :/
yeah yeah I know - but hey, I already have my A-level, oh and your answer is wrong. The diffraction doesn't happen from all the bonds, it only happens with certain planes in the crystal structure.

There's some stuff on it in the file I attached - enjoy.
Attached files
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Stonebridge
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Take a look here

IOP Nuffield Foundation practical on electron diffraction through thin graphite.

http://www.nuffieldfoundation.org/pr...on-diffraction
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GrimlyFish
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(Original post by natninja)
yeah yeah I know - but hey, I already have my A-level, oh and your answer is wrong. The diffraction doesn't happen from all the bonds, it only happens with certain planes in the crystal structure.

There's some stuff on it in the file I attached - enjoy.
It's about the level of accuracy I need when I did this topic :dontknow:
I shall however read the file
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krisshP
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Wavelength of an electron is similar to atomic spacing in graphite.
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