Quantum Physics: Key Terms (Form 5 SPM Physics)

Terms and definitions

• Quantum, The smallest discrete amount of a physical quantity, such as energy, that can exist independently.
• Photon, A single quantum, or particle, of light or other electromagnetic radiation, carrying energy E = hf.
• Planck's constant, The fundamental constant h relating the energy of a photon to its frequency (E = hf), with a value of about 6.63 × 10⁻³⁴ J s.
• Quantum of energy, A discrete packet of energy equal to hf, the smallest amount that can be gained or lost by radiation of frequency f.
• Photoelectric effect, The emission of electrons from a metal surface when light of high enough frequency shines on it.
• Work function, The minimum energy needed to release an electron from the surface of a metal.
• Threshold frequency, The minimum frequency of light needed to cause the emission of electrons from a particular metal surface.
• Wave-particle duality, The concept that light and matter can show both wave-like and particle-like properties depending on how they are observed.
• Photoelectron, An electron emitted from a metal surface as a result of the photoelectric effect.
• Black body radiation, The electromagnetic radiation emitted by an ideal body that absorbs all radiation falling on it, whose spectrum depends only on its temperature.
• Elasticity, The property of a material that allows it to return to its original shape and size after the force deforming it is removed. (related term from another chapter)
• Hooke's law, Within the elastic limit, the extension of a spring is directly proportional to the force applied to it. (related term from another chapter)
• Spring constant, The force needed to produce unit extension in a spring, a measure of its stiffness; measured in newtons per metre (N m⁻¹). (related term from another chapter)
• Elastic limit, The maximum force or extension beyond which a spring or material no longer returns to its original length. (related term from another chapter)
• Limit of proportionality, The point up to which the extension of a spring stays directly proportional to the applied force. (related term from another chapter)

Content standards these terms come from

• 7.1 Quantum Theory of Light
• 7.2 Photoelectric Effect
• 7.3 Einstein's Photoelectric Theory

How to learn them

1. Cover the definition, say it aloud, then check the unit.
2. Pair each term with a formula or experiment from the chapter.
3. Write the Malay term alongside the English one, SPM papers are bilingual.

More Quantum Physics resources

• Chapter overview: Quantum Physics
• Revision Notes
• Common Mistakes
• Practice Questions
• Paper 2 Answering Guide
• Paper 3 Guide
• Calculation practice sets

Source: DSKP KSSM Physics Form 4 and 5 (Versi English), Sijil Pelajaran Malaysia: Format Pentaksiran mulai 2021, Fizik (4531) (Bahagian Pembangunan Kurikulum (BPK), KPM)