Penetrating effects of Radiation (Edexcel GCSE Physics): Revision Notes

1. Alpha Particles (α): Mass & Size: Alpha particles are large and heavy compared to other forms of radiation.

Ionisation: They are highly ionising, meaning they easily collide with atoms and knock electrons off, creating ions.

Penetration:

• Low penetration – due to their size and ionising power, alpha particles quickly lose energy when passing through matter and can be stopped by something as thin as paper or skin.

2. Beta Particles (β): Mass & Speed: Beta particles are smaller and faster than alpha particles, consisting of high-energy electrons.

Ionisation: Beta particles are less ionising than alpha particles because they are smaller and carry less charge, so they interact less readily with atoms in the material.

Penetration:

• Medium penetration – Beta particles can penetrate further than alpha particles but are stopped by materials like aluminium or plastic.

1. Gamma Rays (γ): Mass: Gamma rays have no mass; they are highly energetic electromagnetic waves.

Ionisation: They are poor ionisers, as they pass through materials without much interaction. Despite this, gamma rays still transfer energy and can ionise atoms indirectly.

Penetration:

• High penetration – Gamma rays can pass through most materials and require dense materials like lead or thick concrete to be stopped.