Rutherford scattering experiment

Hi.

I was wondering if someone could please explain to me why it was necessary to remove all of the air from the apparatus of the Rutherford scattering experiment, and why the gld foil needed to be very thin. I've looked all over the net for the answers, and so would really appreciate it if someone could please help.

Thanks.

Cathy

Reply 1

F1 fanatic

16

CathyLou

Hi.

I was wondering if someone could please explain to me why it was necessary to remove all of the air from the apparatus of the Rutherford scattering experiment, and why the gld foil needed to be very thin. I've looked all over the net for the answers, and so would really appreciate it if someone could please help.

Thanks.

Cathy

well think about the situation physically here. What is it you are trying to achieve? One is trying to ascertain the charge distribution of atoms by measurement of angles. It then becomes obvious why it needs to be without air. Air, by definition, contains molecules which will deflect alpha particles in collisions, thereby destroying the actual data from those that pass through the gold foil and are deflected as they are supposed to be by the nucleus. Similarly, with the gold foil, you want to collect all the alpha particles, including those that aren't deviated much. Indeed, one finds that the majority of particles pass through undeviated. If the foil were thick then the alpha particles are likely to be deflected by further gold atoms or to bounce around at odd angles inside the foil or be absorbe all together.

The set up as it is, without air and with the thin foil, means that each alpha particle is deflected by only 1 gold atom, before passing straight through to the detector without its angle being altered. The angle is then a measure of the charge distribution and not of any random statistical events that happened to get in the way.

Reply 2

CathyLou

OP

2

Thanks so much for your help! :biggrin:

Cathy

Rutherford scattering experiment

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