WEBVTT

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[ Music ]

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>> If you have ever been out
in the intense sun too long

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and received a sunburn, you know
how powerful the sun's light

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energy can be.

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Sunlight is a form of energy,
referred to as radiation.

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It travels in waves.

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The distance between the top or
crest of one wave and the crest

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of the next wave is a
wavelength of light.

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Sunlight, also called
white light, is a mixture

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of all visible wavelengths,

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as well as many wavelengths
we can't see.

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When white light
passes through a prism,

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it's bent by different
amounts, spreading out the light

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into a spectrum we see
as different colors.

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The colors appear in order
of their wavelengths,

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with the shortest wavelength,
violet, at one end, and red,

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the longest wavelength, at
the other end of the spectrum.

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While light behaves as waves,
it also acts as if it were made

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up of energy particles
called photons.

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The shorter the wavelength
of light,

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the more energy a
photon carries.

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Certain substances,
called pigments,

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are capable of absorbing
photons and their energy.

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Specific types of pigments
absorb certain wavelengths

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of light and reflect others.

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The different wavelengths
of light absorbed

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by a particular pigment make
up its absorption spectrum.

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Two general types of pigments,
chlorophylls and carotenoids,

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are found in green plants.

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The pigments chlorophyll a

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and chlorophyll b absorb
violet blue and red light.

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Carotenoids absorb
light primarily

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in the violet, blue range.

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You decide.

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Why do plants look green?

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[ Music ]

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Chlorophylls and carotenoids
do not absorb light

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in the green part
of the spectrum.

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Instead, they reflect
green light.

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Consequently, most
plants appear green.