Physics · May / June 2023 · Paper 11 · Question 37

The diagram shows how the thickness of paper is measured during manufacture. If the sheet is too thick, fewer beta-particles can reach the detector. [diagram: paper pulp passing through rollers, with a source of beta-particles above and a detector below, producing a sheet of paper] Why are beta-particles used for this purpose?

1. AAlpha-particles are all stopped by the paper.
2. BAlpha-particles make the paper radioactive.
3. CGamma radiation is all stopped by the paper.
4. DGamma radiation is only produced by sources with a short half-life.

As printed in the paper