Listen&Learn: Science of colour

Learn how our eyes detect colours, and why some light is invisible to humans.

Pre-listening vocabulary

• perception: the understanding of a concept
• visible: able to be seen
• photoreceptor: a type of cell that can detect light
• wavelength: the distance between two peaks of a wave of light
• differentiate: to tell the difference between two or more things
• infrared light: a type of invisible light with a longer wavelength than visible light
• ultraviolet light: a type of invisible light with a shorter wavelength than visible light

Listening activity

Podcast: Play in new window | Download (Duration: 1:56 — 1.8MB)

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Gapfill exercise

The human perception of colour is caused by the way our eyes to light. While humans can see many different colours, light that is visible to humans only makes up a small amount of the light in the . This is because of the limits of the photoreceptors in our eyes. Human eyes contain types of photoreceptors known as cones, which are responsible for detecting coloured light. Because light is made up of , each type of light has a different wavelength. Cones can pick up on these wavelengths, which is how we differentiate between colours. Humans have three types of cones in our eyes – known as red, green, and blue cones. We can see any colour of light with a wavelength within the range of those cones. However, light outside of the visible range – such as infrared and ultraviolet light – can’t be seen by the human eye. Though this light is invisible to us, it isn’t invisible to every . Different animals have different amounts of cones in their eyes. Dogs, for example, only have two types of cones, and therefore can’t see as many colours as we can. An animal known as the mantis shrimp, however, has sixteen types of cones. That means that its range of visible light is much wider than ours, and it can see colours we can’t even .

Comprehension questions

Discussion/essay questions

1. Many scientists have wondered if we all see the same colours, or if we have learned to call different colours the same names. One person could possibly call a colour “red” that another person sees as blue. We have no way of proving or disproving this, because it is difficult to describe what a colour looks like. Do you think it is possible that we all have a different perception of colours?

Transcript

The human perception of colour is caused by the way our eyes respond to light. While humans can see many different colours, light that is visible to humans only makes up a small amount of the light in the universe. This is because of the limits of the photoreceptors in our eyes. Human eyes contain types of photoreceptors known as cones, which are responsible for detecting coloured light. Because light is made up of waves, each type of light has a different wavelength. Cones can pick up on these wavelengths, which is how we differentiate between colours. Humans have three types of cones in our eyes – known as red, green, and blue cones. We can see any colour of light with a wavelength within the range of those cones. However, light outside of the visible range – such as infrared and ultraviolet light – can’t be seen by the human eye. Though this light is invisible to us, it isn’t invisible to every species. Different animals have different amounts of cones in their eyes. Dogs, for example, only have two types of cones, and therefore can’t see as many colours as we can. An animal known as the mantis shrimp, however, has sixteen types of cones. That means that its range of visible light is much wider than ours, and it can see colours we can’t even imagine.