State which type of radiation has the greatest ionising effect.
State which type of radiation is deflected most strongly by a magnetic field.
Fig. 9.1 shows a Geiger-Müller (G.M.) tube and counter. A radioactive source is positioned $10\,\text{cm}$ from the G.M. tube. In Fig. 9.2 a $5\,\text{mm}$-thick piece of metal is placed between the source and the G.M. tube. The counter readings have been corrected for background radiation and show the count rate from the source alone. Explain how the readings demonstrate that the source emits $\beta$-particles and $\gamma$-radiation.
State why the readings cannot be used to demonstrate that the source emits $\alpha$-particles.
Describe one method used to move a radioactive source safely in a school laboratory.