This exam focus covers Exam Focus within Black Body Radiation for GCSE Physics. Revise Black Body Radiation in Energy for GCSE Physics with 16 exam-style questions and 5 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 5 of 7 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
🎯 Exam Focus
Frequently Examined
This topic is examined in Edexcel 1PH0/1 (Paper 1). Edexcel questions often present a data set — such as radiation spectra for two stars or the Earth — and ask you to compare temperatures using peak wavelength, or to explain the greenhouse effect mechanism in a given context. Expect "Suggest" and "Explain" command words worth 3–4 marks. Common question types:
- Define a black body (2 marks) — must name both properties: perfect absorber AND perfect emitter
- Describe how radiation emitted changes with temperature (3 marks) — total increases, peak wavelength decreases, peak frequency increases
- Explain the greenhouse effect (4 marks) — absorption, re-emission in all directions, less escaping to space, temperature rise to new equilibrium
- Compare two objects using peak wavelength data (2 marks) — shorter peak wavelength = higher temperature
- Radiation balance / Earth's temperature (3 marks) — absorbed solar = emitted infrared at stable temperature
The most common mistake: saying greenhouse gases "block" incoming sunlight. They absorb the infrared radiation emitted by the Earth, not the incoming solar radiation.
Practice questions for Black Body Radiation
What is a perfect black body?
Explain how the radiation emitted by an object changes as its temperature increases.