Physics · 5.2.2 Radioactive emissions · α β γ
α, β & γ Radiation. Deflect it.
Fire alpha, beta and gamma radiation through a field and through absorbers. Alpha (+, heavy) deflects a little; beta (−, light) deflects the opposite way and more; gamma (no charge) goes straight. Penetration is the reverse order.
0625 Topic 5.2.2 — α, β, γ
Deflection in fields
Penetration & ionisation
Field
—
1.0
Properties
Selected
Alpha (He nucleus)
Charge
+2
Stopped by
a sheet of paper
Ionising power
very high
α (+, heavy): small deflection, most ionising, least penetrating. β (−, light): bigger opposite deflection. γ (neutral): no deflection, most penetrating.
📋 Comparison (Cambridge)
- Alpha (α) — a helium nucleus (2p + 2n), charge +2, heavy and slow. Most ionising, least penetrating — stopped by paper or a few cm of air. Deflects slightly (opposite to beta).
- Beta (β) — a fast electron, charge −1, light. Medium ionising and penetration — stopped by a few mm of aluminium. Deflects more, opposite direction to alpha.
- Gamma (γ) — high-energy EM wave, no charge or mass. Least ionising, most penetrating — reduced by thick lead/concrete. Not deflected by fields.
- In a magnetic field, α and β curve in opposite directions (opposite charges); γ goes straight.
🎯 Syllabus reference (0625)
- 5.2.2 The three types of nuclear emission — describe the nature of α, β and γ; compare their penetrating power, ionising effect, range and deflection in electric and magnetic fields; identify the absorber that stops each.