- #1

MortalWombat

- 4

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Hello all you physics folks,

this is my first post, so if I screw this up, go easy on me :)

Here's the problem I'm working on and that I simply can't get my head wrapped around:

I have a table of 10 values of counts per second (cps) of alpha decay of Americium-241, depending on the pressure ##p## inside a chamber, where at a distance of ##x_0 = 6## cm a detector is mounted.

I have to plot the cps...but not against the pressure, but a distance corresponding to that pressure at normal pressure levels (##p = 1 bar##). I am to use Boyle-Marriots law

$$

p \cdot V = p \cdot A \cdot x = const.

$$

Since the cross-section of the chamber ##A## can be considered constant, we have

$$

p \cdot x = const.

$$

But this means that for decreasing pressure the distances get longer (that makes sense), but when I plot ##p_i## vs ##x_i##, I get an increasing cps count for longer distances, which is pretty much the opposite of what we'd want...any idea where I made a mistake here? Do I have to modify the cps counts in any way?

EDIT: my bad, I wanted to post a screenshot of my current graph

http://imgur.com/vegvPSu

this is my first post, so if I screw this up, go easy on me :)

Here's the problem I'm working on and that I simply can't get my head wrapped around:

I have a table of 10 values of counts per second (cps) of alpha decay of Americium-241, depending on the pressure ##p## inside a chamber, where at a distance of ##x_0 = 6## cm a detector is mounted.

I have to plot the cps...but not against the pressure, but a distance corresponding to that pressure at normal pressure levels (##p = 1 bar##). I am to use Boyle-Marriots law

$$

p \cdot V = p \cdot A \cdot x = const.

$$

Since the cross-section of the chamber ##A## can be considered constant, we have

$$

p \cdot x = const.

$$

But this means that for decreasing pressure the distances get longer (that makes sense), but when I plot ##p_i## vs ##x_i##, I get an increasing cps count for longer distances, which is pretty much the opposite of what we'd want...any idea where I made a mistake here? Do I have to modify the cps counts in any way?

EDIT: my bad, I wanted to post a screenshot of my current graph

http://imgur.com/vegvPSu

Last edited: