AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
(HT only) Different substances may absorb, transmit, refract or reflect…
Full specification wording
Properties of electromagnetic waves 1: (HT only) Different substances may absorb, transmit, refract or reflect electromagnetic waves in ways that vary with wavelength.
When electromagnetic waves meet a substance, absorption, transmission, refraction or reflection can occur.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 1 of 5
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
When electromagnetic waves meet a substance, absorption, transmission, refraction or reflection can occur. The effect depends on the substance and the wavelength. For example, visible light passes through glass (transmission) but ultraviolet is strongly absorbed; radio waves pass through walls while visible light does not. Refraction happens when a wave changes speed at a boundary, and the amount of bending varies with wavelength. Reflection also varies: shiny metals reflect visible and infrared strongly, and bulk metals reflect radio waves. To describe these effects, name the substance, name the wave region, and state the effect and how it changes with wavelength.
What earns the marks
- Absorption: the wave's energy is transferred to the substance, often increasing its internal energy; the amount absorbed depends on the substance and wavelength.
- Transmission: the wave passes through the substance; a substance may transmit some wavelengths well and absorb others, as with coloured filters or glass.
- Refraction: the wave changes direction at a boundary because its speed changes; the change in speed, and so the bending, varies with wavelength.
- Reflection: the wave bounces off a surface; the proportion reflected depends on the substance and wavelength, for example bulk metals reflecting radio waves.
- A correct answer links a named substance to a named electromagnetic wave region and states how the effect varies with wavelength, rather than treating all wavelengths alike.
Common mistakes and how to put them right
Treating all electromagnetic waves as behaving identically in a substance.
Put it right: State that absorption, transmission, refraction and reflection can each vary with wavelength, and give a specific example such as glass transmitting visible light but absorbing ultraviolet.
Confusing refraction with reflection.
Put it right: Refraction is a change of direction due to a change of speed inside a substance; reflection is bouncing off a surface.
Saying a substance 'absorbs' a wave when it actually transmits it, or vice versa.
Put it right: Check whether the wave passes through, is taken in, bends or bounces, and use the precise term.
Exam tips
- Name the substance and the electromagnetic wave region in every example, then state the effect and how it varies with wavelength.
- Use the four key terms precisely: absorb, transmit, refract, reflect; avoid vague words such as 'goes through' or 'bounces'.
Try the lesson
The start of the Properties of electromagnetic waves 1: (HT only) Different substances may absorb, transmit, refract or reflect electromagnetic waves in ways that vary with wavelength. lesson, made from checked teaching notes for this specification point.
Have a go first
When a beam of white light enters a glass prism, it splits into a spectrum of different colours. Which statement explains why this happens?
Listen
When electromagnetic waves meet a substance, absorption, transmission, refraction or reflection can occur. The effect depends on the substance and the wavelength. For example, visible light passes through glass (transmission) but ultraviolet is strongly absorbed; radio waves pass through walls while visible light does not. Refraction happens when a wave changes speed at a boundary, and the amount of bending varies with wavelength. Reflection also varies: shiny metals reflect visible and infrared strongly, and bulk metals reflect radio waves. To describe these effects, name the substance, name the wave region, and state the effect and how it changes with wavelength. A strong answer earns marks for these points. Absorption: the wave's energy is transferred to the substance, often increasing its internal energy; the amount absorbed depends on the substance and wavelength. Transmission: the wave passes through the substance; a substance may transmit some wavelengths well and absorb others, as with coloured filters or glass. Refraction: the wave changes direction at a boundary because its speed changes; the change in speed, and so the bending, varies with wavelength. Reflection: the wave bounces off a surface; the proportion reflected depends on the substance and wavelength, for example bulk metals reflecting radio waves. A common slip: Treating all electromagnetic waves as behaving identically in a substance. Instead, state that absorption, transmission, refraction and reflection can each vary with wavelength, and give a specific example such as glass transmitting visible light but absorbing ultraviolet. Exam tip: Name the substance and the electromagnetic wave region in every example, then state the effect and how it varies with wavelength.
See it
Key words
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Absorption
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Transmission
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Refraction
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Reflection
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See every definition
- Absorption
- The wave's energy is transferred to the substance, often increasing its internal energy, and the amount absorbed depends on the substance and wavelength.
- Transmission
- The wave passes through the substance, and a substance may transmit some wavelengths well and absorb others.
- Refraction
- The wave changes direction at a boundary because its speed changes, and the change in speed, and so the bending, varies with wavelength.
- Reflection
- The wave bounces off a surface, and the proportion reflected depends on the substance and wavelength.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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