Random Nature of Radioactive Decay (OCR GCSE Physics A (Gateway Science Suite)): Revision Notes

4.2.4 Random Nature of Radioactive Decay

Range, Penetrating Power, and Ionising Power

Range in Air

• Alpha Particles:
  • Large and can travel around 5 cm in the air before they collide with air particles and stop.
• Beta Particles:
  • Can travel further; they can reach about 15 cm in the air before stopping.
• Gamma Radiation:
  • Travels several metres in the air before stopping.

Penetrating Power

• Alpha Particles:
  • Stopped by a single sheet of paper.
• Beta Particles:
  • Stopped by a few millimetres of aluminium.
• Gamma Radiation:
  • Stopped by several centimetres of lead.

Ionising Power

• When radiation collides with atoms, it can cause the atoms to lose electrons and form ions.
• Alpha Particles:
  • Very strongly ionising.
• Beta Particles:
  • Quite strongly ionising.
• Gamma Radiation:
  • Weakly ionising.