| English | Quantum of energy |
|---|---|
| Bahasa Melayu | Kuantum tenaga |
| 中文 | 能量子 |
Definition
A discrete packet of energy equal to hf, the smallest amount that can be gained or lost by radiation of frequency f.
In exam terms
A quantum of energy is a discrete packet of energy equal to E = hf, the smallest amount that can be gained or lost by radiation of frequency f. Here h is Planck's constant (6.63 × 10⁻³⁴ J s), f is the frequency in hertz (Hz), and E is in joules (J).
Energy is not exchanged continuously but in whole numbers of these packets. A correct exam sentence: An atom can only emit or absorb energy in whole quanta, each equal to hf. For light of a given frequency, every packet carries exactly the same energy hf.
Do not confuse it with…
Do not confuse a quantum of energy with the work function of a metal. A quantum of energy is the energy hf carried by one packet of radiation of frequency f; the work function is the fixed minimum energy needed to release an electron from a particular metal.
One depends on frequency, the other is a property of the metal.
In Paper 2 this is asked as define a quantum of energy, or calculate its size using E = hf. Keep f in Hz, quote E in J, and remember energy comes only in whole multiples of hf, never in fractions.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)