|What are the atoms doing in rainbows?|
|Question Date: 2017-03-28|
Inside a rainbow, water molecules are the only
atoms that are there. The other thing that causes
a rainbow is sunlight. This is why rainbows are
usually seen during or after rain.
Sunlight is a white light, which is a
combination of all different colors that we can
see. All the colors in the rainbow have their own
amount of energy, and when seen at the same time
make white light.
When light travels through rain and hits a
raindrop, it bends the light at some angle.
For white sunlight, since it is a combination of
different colors, the raindrop bends certain
colors more than others depending on how much
energy they have. This means that red light
will be reflected off a raindrop at one angle, and
purple light will be reflected at a deeper angle.
This causes the rainbow we see in the sky, where
all the colors of light are spread out at
The water molecules just sit in the air and
wait for sunlight. When light hits these
molecules, the reflected light makes a rainbow in
the sky! Hope this answers your question.
Not much - the atoms aren't what causes the
rainbow. Rainbows are created by drops of water
that reflect light off of the back of the
droplet. Because light travels slower in water
than it does in air, and because different colors
of light travel at different speeds when moving
through water, the different colors bend different
amounts when passing through a raindrop and being
bounced. This smears the white light from the sun
into the many colors that make up white light,
which is why you see a smear of color.
The atoms of the rainbows you are talking about
are actually atoms from the molecule of water,
H2O! After if rains, there’s a lot of
water in the sky and when the clouds start to
disappear after a storm, light starts to hit those
water droplets. The light enters a rain droplet
at a specific angle and reflects some of it, which
we see as a color. The color that the rain
droplet reflects and shows depends on the angle
the light enters. That’s why you always see red at
the top of the rainbow, and purple at the bottom!
One rainbow requires millions of rain droplets
to create a rainbow. The rainbow is actually a
complete circle, but we only see half of it
because it is cut off by the ground.
On the atom level, they are doing the same motions
as they are doing in their regular phase. There is
no big difference in such small level.
So the only atoms really involved in
rainbows are the atoms in water molecules.
When the light from the sun hits a water droplet
in the air (like after it rains), the light
bounces off the back of the water droplet.
When the light leaves the water droplet, it’s
now been split into different colors. What the
atoms are doing is changing the sunlight in such a
way that the sun’s white light is split into
multiple colors. To understand rainbows, it’s
actually better not to think of it in terms of
atoms, but instead in terms of the whole water
droplet. When you try to understand what happens
with light and atoms, it gets really complicated,
really quickly. It’s important to realize that the
rainbow isn’t in a single place. You only see a
rainbow if you are facing the sun in the right
way, and it will always seem far away from
you. Keep in mind that the sun’s rays are going to
hit the water droplets in the air all at the same
time, though you’ll only see a rainbow if you’re
standing the right place.
This is a really fun question because you’re
using your understanding of atoms and you’ve made
a really good guess at how rainbows work. The
funny thing is, the atoms themselves aren’t doing
much to create the rainbow. The molecule
(which is particle made up of one or more atoms)
that is responsible for rainbows is water. Do
you remember what the formula for water is?
It’s H2O. Water molecules like to
stick to other water molecules and if they are
light enough they can float in air. If too many of
them stick together, they’ll be too heavy to float
and they’ll fall as rain. After a storm, most of
the water (that we saw as clouds) has fallen but
there is a little bit left in the air. When light
from the sun (which contains all colors) passes
through these water droplets in the sky, the light
separates into its individual colors. When the
light splits into its individual colors we see a
rainbow! This splitting is called
refraction and is really complicated, but
it boils down to the idea that every color of
light is a little bit different so they interact
with the water droplet differently. To summarize,
the atoms are making up water molecules that
refract each color in white light slightly
differently which looks like a rainbow when in the
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