How Do You Calculate the Activity of a Radioactive Sample?

[jumbogala]

Homework Statement

The sample is placed 0.12 m beneath a Geiger counter.

The counter registers 2 counts per second. What is the activity of the sample?

Homework Equations

The Attempt at a Solution

Just a guess. I am making up formulas here so please tell me if they're not even true.

(2 counts/s)/(2E-4 m²) = Intensity = 10 000 counts/s/m²

Then multiply this by the distance to get the activity? So this would give 1200 counts/s?

Is that correct?

 

[gneill]

Do you suppose that all the particles emitted by the sample are being captured by the Geiger counter?

 

[jumbogala]

Nope, they're not. But I don't know how to account for that, since I have no idea what percentage are.

 

[gneill]

Nope, they're not. But I don't know how to account for that, since I have no idea what percentage are.

What if you assumed that the sample emits uniformly in all directions?