Inverse Square Spreading Cuts Count Rate - Nuclear Radiation: Decay, Binding, and Shielding Step by Step

Doubling distance cuts a training count rate by four. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Inverse-square spreading cuts count rate

Doubling distance from 2 metres to 4 metres divides the count rate by 4.

80\div4=20\ 1/\mathrm{s}

The source strength did not change

The count rate changes because the same radiation budget spreads over more area.

\mathrm{rate}=20\ 1/\mathrm{s}