Physics – 5.2.2 The three types of nuclear emission | e-Consult

A half-life of 5 seconds means that after 5 seconds, half of the original number of radioactive nuclei in a sample will have decayed into other elements or isotopes. This decay is a random process; we cannot predict which individual nucleus will decay at any given time. However, we can predict the probability of decay within a given time interval.

Over time, the number of radioactive nuclei in the sample decreases exponentially. Each half-life represents a halving of the remaining radioactive nuclei. After 5 seconds, 50% remain; after 10 seconds, 25% remain; after 15 seconds, 12.5% remain, and so on. This exponential decay is a direct consequence of the spontaneous and random nature of the decay process.

The emission of radiation is random in direction because the decay occurs within the nucleus, and the emitted particles are not constrained by any external forces or a specific orientation. The nucleus is a very small, dense object. The emitted particles (alpha, beta, or gamma) are released from within this nucleus and travel outwards. There is no 'center' from which the radiation is emitted in a particular direction. The probability of detecting a particle in any given direction is uniform, reflecting the isotropic nature of the decay process within the nucleus. The nucleus itself doesn't have a preferred direction of decay; it's a random event occurring within the confines of the nucleus, leading to a random distribution of emitted radiation.