A group of students uses 1200 dice, each with nnn sides, to model the decay of a radioactive material. Each die represents a single undecayed nucleus. A roll of the dice represents a constant time interval.
When the dice are rolled, those that show a 1 represent decayed nuclei and are removed. The students count the number NNN of 'undecayed' dice that remain. The procedure is repeated using the remaining undecayed dice.
The figure below shows the students' data.
Explain why NNN has been plotted on a logarithmic scale.
In this experiment, a decay constant λ\lambdaλ can be defined that models the radioactive decay constant. Determine λ\lambdaλ in roll−1\text{roll}^{-1}roll−1. Go on to use your value for λ\lambdaλ to show that n=6n = 6n=6 for the dice used in this experiment.
A typical radioactive source used in high-school demonstrations has an activity of 80 kBq80\text{ kBq}80 kBq. A medical radiotherapy source used in a hospital has an activity of 250 GBq250\text{ GBq}250 GBq. State one safety precaution when using the source in a school laboratory, and explain how this safety measure must be adapted for safe use of the hospital radiotherapy source.
