Cambridge IGCSE Physics Notes 3.3: Electromagnetic Spectrum
Cambridge IGCSE Physics notes on the electromagnetic spectrum, wavelength, frequency, speed, uses, hazards, communication, and ionisation.
Q: What does Cambridge IGCSE Physics Notes 3.3: Electromagnetic Spectrum cover?
A: It follows official Cambridge Physics section 3.3 for syllabuses 0625 and 0972, with Core ideas separated from Supplement depth.
All electromagnetic waves are transverse and travel at the same speed in vacuum, but their frequencies determine their interactions, uses, and hazards.
The ideas that organise this section
- Learn the spectrum order once, then reason inversely between wavelength and frequency.
- Match a use to a physical property rather than memorising an isolated pairing.
- Higher-frequency radiation can carry greater photon energy and may ionise matter.
Core route
Core candidates should be ready to describe, calculate, interpret, and apply the following:
- State the spectrum order and common uses and hazards.
- Recall that all electromagnetic waves travel at the same speed in vacuum.
- Relate wavelength and frequency using wave speed.
Supplement route
Extended candidates study all Core content and add the following depth:
- Explain communication choices through diffraction, penetration, bandwidth, atmosphere, and satellite paths.
- Distinguish heating effects from ionising damage.
- Apply spectrum information to unfamiliar technology or safety contexts.
Formula route
- Relationship: wave speed = frequency x wavelength.
Write the relationship before substituting. Convert units first, keep extra figures during working, and round only the final answer to sensible precision.
Build a connected model
In Electromagnetic Spectrum, a strong answer connects the named quantity or model to observable evidence. Begin by defining the physical quantity in words or with its relationship. Identify which values are scalars and which require a direction. Represent the situation with a labelled diagram, graph, field pattern, ray or circuit when that makes the relationship visible. The representation is part of the reasoning: its labels, arrows and scale should agree with the written explanation.
For a calculation, write the governing relationship before substitution, convert prefixes and time units, keep unrounded values during working and attach the correct final unit. For a qualitative question, use a cause-link-consequence chain. Name what changes, state the physical mechanism that links the change to the system, and then give the measurable result. If two cases are compared, hold unrelated variables constant and use the same physical principle for both.
