I have a simple theoretical question regarding half-life decay graphs for radioactive substances.
If the graph plots activity versus time (not mass versus time), then what physical quantity can possibly be deduced from the graph? I'm tempted to think that "half-life" is a quantity that can be deduced... but I'm not sure if that qualifies as a "physical" quantity?
I also know that the number of counts is directly proportional to the amount of radioactive substance available. I don't have the mass given in the graph, but just have the counts and the time. Can we somehow deduce the the amount of substance available?
The graph given in the problem is very simple, it has only counts plotted against time.