| English | Quantum |
|---|---|
| Bahasa Melayu | Kuantum |
| 中文 | 量子 |
Definition
The smallest discrete amount of a physical quantity, such as energy, that can exist independently.
In exam terms
A quantum (plural: quanta) is the smallest discrete amount of a physical quantity that can exist independently. In SPM Physics the key example is energy: energy is not continuous but comes in fixed packets.
The size of one quantum of energy is E = hf, where h is Planck's constant (6.63 × 10⁻³⁴ J s) and f is the frequency in hertz (Hz), giving E in joules (J).
A correct exam sentence: Light energy is emitted or absorbed only in whole quanta, each of size hf. The idea of quantisation is the basis of Planck's quantum theory.
Do not confuse it with…
Do not confuse quantum with photon. A quantum is the general idea of a smallest discrete packet of any quantity; a photon is specifically one quantum of electromagnetic radiation.
Every photon is a quantum of light energy, but 'quantum' is the broader term.
In Paper 2 this is asked as state what is meant by a quantum, or explain quantisation of energy. When answering, stress two ideas: the amount is discrete (comes in fixed packets), and it is the smallest unit that can exist on its own.
Avoid vaguely writing 'a small amount of energy'.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)