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Rutherford Gold Foil Experiment

The main features in this experiment is Rutherford's use of a...

a) narrow beam of alpha particles
b) alpha particles all with the same speed and kinetic energy
c) the source of the alpha particles must have a long half-life
d) evacuated chamber
e) thin gold foil

What are the reasons for these features?

I do know that one reason of the use of e) was otherwise the alpha particles are deflected more than once which will be detected by the detector. Can anyone tell me another reason?


I do know the reason for d) .. to prevent air particles deflecting the alpha particles.

Thanks for any replies in advance.
Reply 1
Avatar for abbii
abbii
11
a) a narrow beam so that the angle of deflection can be assumed to be from a single point
c) possibly that alpha particles must be emited at a slowish rate so they to not collide with each other and react
Reply 2
Avatar for Aiboz
Aiboz
OP
c) The source must have a long half-life otherwise later readings would be lower than earlier readings due to radioactive decay of the source nuclei.

Don't know about the others though. Edit: specifically e) and b)
Reply 3
Avatar for 1zzy
1zzy
e) Gold because it's a malleable metal so can be easily rolled into thin foils - and thin foils because the alpha particles would be stopped by thick foils (thus scattering would not be observed).
Reply 4
Avatar for AlphaMale1
AlphaMale1
particles must have the same speed as if the went faster past a gold atom in the foil it wouldnt deflect as much as if it were going slower.
Reply 5
Avatar for Hubble10
Hubble10
b.) The alpha particles must have the same speed and KE. Otherwise, slow alpha particles would be deflected more than faster alpha particles on the same initial path.
a) because the experiment involves measuring scatter. It's no good if half your particles are already scattered from the start
b) not entirely sure. My guess is so there are fewer variables affecting the deflection i.e. a faster particle might be deflected less than a slower one.
c) I would assume it needs to have a long half life so that you can actually get some results, as well as lower the activity so the particles aren't deflecting off of each other. Also, safety reasons. If it has a short half life, it's likely highly radioactive which isn't good for you.
And finally, a 2nd reason for e) is that the foil is what is deflecting the particles. Needs to be thin for the reason you stated, I would guess that it needs to be gold since it can be easily hammered into foil
Just my 2 cents on this.

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