Chemistry Question?

Question

I am working on my Chemistry homework for this college class but I am having trouble with this question.

At 3.00 m from a radioactive source the intensity of its gamma radiation is 202 roentgen. How far away would we need to be reduce the intensity to 4.64 roentgen.

Answer 1

See if I can remember how to do this:

Intensity at distance = d => I(d)
Intensity at distance = 1 meter => I(o)
therefore I(d) = I(o)/d^2

First, you need to find I(o)

I(d) at 3 meters = 202R, so 202 = I(o)/(3^2) = I(o)/9, or
I(o) = 9*202 = 1818 Roentgens at one meter

4.64 R = 1818R/d^2, thus

1818/4.64 = d^2 = 391.81 m^2, or

d=19.79 m

Answer 2

That's more of a physics question or a math question.

It's an inverse-square law. Unfortunately, I don't have my scientific calculator handy and I'm drunk as well. Let me see if I can do it on a note pad.

My note pad tells me approximately 36 meters.

Answer 3

you need to be more specify