Alpha, Beta, and Gamma Radiation - SS2 Physics Lesson Note

Alpha, beta, and gamma radiation are three types of ionising radiation that are emitted during radioactive decay. They differ in terms of their composition, penetrating power, and ability to ionise matter.

Alpha Radiation:

Alpha radiation consists of alpha particles, which are composed of two protons and two neutrons (essentially a helium nucleus). Alpha particles have a positive charge and are relatively large and heavy compared to other types of radiation. Due to their size and charge, alpha particles have a limited range and are easily stopped by a few centimetres of air or a sheet of paper. However, they possess high ionising power and can cause significant damage to living tissue if inhaled or ingested. Alpha decay occurs when a nucleus emits an alpha particle, reducing its atomic number by 2 and its mass number by 4.

Beta Radiation:

Beta radiation consists of beta particles, which are high-speed electrons (beta-minus) or positrons (beta-plus). Beta particles have a negative charge and are much smaller and lighter than alpha particles. They can travel further through matter than alpha particles, typically several metres in air or a few millimetres in solid materials. Beta particles have moderate ionising power and can penetrate the skin, potentially causing damage to living tissue. Beta decay occurs when a nucleus undergoes a transformation, releasing an electron (beta-minus decay) or a positron (beta-plus decay).

Gamma Radiation:

Gamma radiation consists of electromagnetic waves of very high frequency and energy. Gamma rays have no mass or charge and travel at the speed of light. They possess excellent penetrating power and can travel long distances through matter, requiring thick lead or concrete shielding to attenuate their intensity. Gamma rays have lower ionising power compared to alpha and beta particles but can still cause damage to cells and DNA. Gamma radiation is emitted during nuclear decay processes or as a result of nuclear reactions.

It is important to note that all three types of radiation can be harmful to living organisms if exposed in excessive amounts. Proper safety precautions and shielding measures are necessary when working with or around radioactive materials.