Zicoflex LIGHT
WHAT IS
LIGHT?
HOW DOES
LIGHT
TRAVEL?
WHAT ARE
SHADOWS?
WHAT MAKES
SOME
MATERIALS
OPAQUE?
REFLECTION
REFRACTION
LASER
FIND OUT
MORE
Light is a type of
energy known as
electromagnetic
radiation. It is given
out by hot objects
such as the Sun,
light bulbs, and
LASERS. When light
hits a surface, its
energy can be
absorbed (soaked
up), REFLECTED, or
deflected by
REFRACTION.
WHAT IS
LIGHT?
Light is made up of
little packets of
energy called
photons. Most of
these photons are
produced when the
atoms in an object
heat up. Heat
“excites” the
electrons inside the
atoms and they
gain extra energy.
This extra energy
is then released as
a photon. The
hotter an object
gets, the more
photons it gives
out.
HOW DOES
LIGHT TRAVEL?
Light travels as a
wave. But unlike
sound waves or
water waves, it
does not need any
matter or material
to carry its energy
along. This means
that light can travel
through a vacuum
—a completely
airless space.
(Sound, on the
other hand, must
travel through a
solid, a liquid, or a
gas.) Nothing
travels faster than
light energy. It
speeds through the
vacuum of space
at 186,400 miles
(300,000 km) per
second.
WHAT ARE
SHADOWS?
Light waves travel
out from their
source in straight
lines called rays.
Rays do not curve
around corners, so
when they hit an
opaque object (one
that does not allow
light to pass
through it), they
are blocked from
reaching the other
side of that object.
We see a dark
shadow in the area
from which light is
blocked.
WHAT MAKES
SOME
MATERIALS
OPAQUE?
When light falls on
a material, the
energy in its
photons can affect
the atoms in the
material. In some
materials, such as
metal, the atoms
absorb some of
the photons so
light does not pass
through them.
These materials
are opaque. In
other materials,
such as glass, the
atoms cannot
absorb the photons
and light passes
through them.
These materials
are transparent.
REFLECTION
Light rays reflect
(bounce) off
objects. The Moon
shines because it
reflects light from
the Sun. Smooth
surfaces, such as
mirrors, reflect
light in one
direction.
WHAT HAPPENS
WHEN YOU
LOOK IN A
MIRROR?
At first sight, your
image is identical to
you. But a closer
look shows that as
you lift your right
hand, your image
raises its left.
Reflection always
flips an image from
left to right. If you
hold up a sheet of
paper with writing
on it, the image in
the mirror shows
the writing in
reverse.
REFRACTION
Light travels more
slowly through
some materials
than others. The
change in speed
can cause light rays
to change direction.
This directional
change is called
refraction.
WHY IS A
SWIMMING
POOL DEEPER
THAN IT
LOOKS?
Refraction can
make things look
closer than they
really are. The
difference in speed
between light
traveling through
water and through
air means that,
from the surface, a
13-ft (4-m) pool
appears to be just
10 ft (3 m) deep.
Glass is another
material that
refracts light. It is
used to make
eyeglasses and
other lenses.
LASER
A laser produces an
incredibly powerful,
concentrated form
of light. Inside a
laser, light waves
are bounced back
and forth between
two mirrors to
build up energy
before being
released as a
narrow beam.
WHY IS LASER
LIGHT SO
SPECIAL?
Laser light does not
spread out in the
way that light
from other sources
does. All the light
waves in laser light
are precisely in
step with each
other. As a result,
laser light can be
concentrated and
controlled far more
accurately. It can
carry television and
other signals over
great distances
without losing
quality.