New trends in physics teaching, v.4; The ... - unesdoc - Unesco

Colour
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Light
Incident +
From Iris
Cone Cells
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J
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Figure 28. Trajectory of light in the cone cells.
The absorption of light by the visual pigment in the cones has been measured and is shown in
figure 29. The three types of spectral absorption curve are thought to be the source of three
colour vision. The active substance is called ‘iodopsin’, but its exact chemical nature is still
unknown.
Wavelength/nm
Figure 29. Percentage absorption of light of different wavelengths by the dye present in the three types of cone cell of the eye
in primates.
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