| English | Nuclear fusion |
|---|---|
| Bahasa Melayu | Pelakuran nukleus |
| 中文 | 核聚变 |
Definition
The joining of two light nuclei to form a heavier nucleus, releasing a large amount of energy, as happens in the Sun.
In exam terms
Nuclear fusion is the joining of two light nuclei to form a single heavier nucleus, with a small amount of mass converted into a large release of energy according to E = mc² (c = 3.0 × 10⁸ m s⁻¹). Energy released is measured in joules (J).
Fusion needs extremely high temperature and pressure so that the positively charged nuclei can overcome their electrostatic repulsion and get close enough to join. In the Sun, hydrogen nuclei fuse into helium.
A correct exam sentence: Two deuterium nuclei fuse to form a helium nucleus, releasing energy because the products have less mass than the reactants.
Do not confuse it with…
Do not confuse fusion with nuclear fission. Fusion joins two light nuclei into a heavier one; fission splits one heavy nucleus (such as uranium-235) into two lighter nuclei.
Both release energy, but by opposite processes and with different fuels.
In Paper 2 this is usually asked as state the meaning of nuclear fusion, or compare fusion and fission. When comparing, always name the direction (join versus split), the type of nuclei (light versus heavy) and the condition (fusion needs very high temperature).
Do not simply write 'they release energy'.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)