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Diffraction of Electrons :P

Any one share some love and help?! :biggrin:

Im writing about the observations....

I need about 4...
I've got

1 - Bright + dark fringes - Explained using superposition

But the other 3, i need some checking ?
I think they are..

2 - Brighter screen when higher voltage, because f = E (kin ) / h,
increase in kinetic energy gives higher frequency..... which gives a larger resultant phasor + therefore a brighter ring? is that right? im not too sure :frown:

3 - Smaller diameter rings with higher voltage, using de broglie relations hip,

as Velocity increases due to higher voltage, wavelength decreaseas as L = h /mv, where L = wavelength. A smaller wavelength gets defracted less so smaller diameter rings? is that right?

and 4 - Ring radius increasing by decreasing the slit spacing...leading to an increase in fringe spacing = increase in ring radius?

I think/hope number 1 is correct... could any one help on the other 3 or provide other observations? Number 4 i just randomly thought of just by changing an element in the equation...does it even count as an oberservation?

Thanks SO much for any help, im going insane, my worst subject but the one i need the most, thanks SOOO much in advance,
Reply 1
Avatar for Drummy
Drummy
10
The rings are also brighter because more electrons hit the screen when a higher voltage is used.

You could also mention why there are 2 rings when using a graphite target (because there are 2 characteristic spacings in the graphite)

have a look at
http://www.stokesleyscience.org/A%20level%20Physics/quantumP/electron_diffraction.htm
Reply 2
Avatar for lilpenguin
lilpenguin
OP
1
Thank you! That site looks great. :biggrin:

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