| English | Work function |
|---|---|
| Bahasa Melayu | Fungsi kerja |
| 中文 | 逸出功 |
Definition
The minimum energy needed to release an electron from the surface of a metal.
In exam terms
The work function is the minimum energy needed to release an electron from the surface of a metal. Its symbol is W, and it is measured in joules (J) (sometimes electronvolts, eV).
It is a fixed property of each metal.
It links to the threshold frequency by W = hf₀, where h is Planck's constant and f₀ is the threshold frequency. In Einstein's equation hf = W + KE(max), the photon energy must first supply W before any electron gains kinetic energy.
A correct exam line: W = hf₀ = (6.63 × 10⁻³⁴ J s)(5.0 × 10¹⁴ Hz) = 3.3 × 10⁻¹⁹ J.
Do not confuse it with…
Do not confuse the work function with the threshold frequency. The work function is an energy (in J); the threshold frequency is a frequency (in Hz).
They describe the same barrier from different angles and are linked by W = hf₀.
In Paper 2 this is asked as define the work function, or calculate it from the threshold frequency using W = hf₀. When defining, always say 'minimum energy to release an electron from the metal surface', do not just write 'energy to remove an electron', and always give the unit as J.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)