Pearson Edexcel · GCSE · Physics
Course version: 1PH0 · Version from Sept 2016
Recall that different substances may absorb, transmit, refract or reflect…
Full specification wording
Topic 4 – Waves: 4.11 Recall that different substances may absorb, transmit, refract or reflect waves in ways that vary with wavelength
When waves meet a substance, four things can happen: the substance can absorb the wave (taking in its energy), transmit it (let it pass through), refract it (change its speed and direction on…
Checked against the Pearson Edexcel 1PH0 specification (opens in a new tab) on .
- Point 11 of 15
Study notes
From the checked teaching notes for this specification point.
The idea
When waves meet a substance, four things can happen: the substance can absorb the wave (taking in its energy), transmit it (let it pass through), refract it (change its speed and direction on entering) or reflect it (send it back). How much of each happens depends on the substance and on the wave's wavelength. For example, glass transmits visible light well but absorbs much ultraviolet; a red filter transmits red light and absorbs other visible wavelengths; some surfaces reflect certain wavelengths more than others. So the same substance can behave differently for different wavelengths, which is why wavelength matters when choosing materials for lenses, filters and sun protection.
What earns the marks
- Names absorption, transmission, refraction and reflection as possible outcomes when waves meet a substance.
- States that the way a substance affects waves depends on the wavelength of the wave.
- Gives an example of a substance transmitting some wavelengths and absorbing others.
- Recognises that the same substance can reflect, refract, absorb or transmit different wavelengths to different extents.
Common mistakes and how to put them right
Treats a substance as behaving identically for all wavelengths.
Put it right by stating that absorption, transmission, refraction and reflection vary with wavelength.
Confuses transmission with refraction.
Put it right by describing transmission as passing through and refraction as a change of speed and direction on entering.
Omits one of the four outcomes.
Put it right by listing absorption, transmission, refraction and reflection together.
Exam tips
- Learn all four outcomes as a set so a multiple-choice option naming only some can be judged against the full list.
- Attach a concrete example, such as a coloured filter transmitting one band of visible wavelengths and absorbing the rest.
- Read the question for the word 'wavelength' and check whether the option explains variation with wavelength.
Try the lesson
The start of the Topic 4 – Waves: 4.11 Recall that different substances may absorb, transmit, refract or reflect waves in ways that vary with wavelength lesson, made from checked teaching notes for this specification point.
Have a go first
A sheet of red glass lets red light pass through it but absorbs most blue light. Which word describes what the red glass does to the red light?
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