|
Visible light is part of the
electromagnetic spectrum of waves. What makes visible
light different is that it is a series of
electromagnetic wavelengths that we can detect or see.
These wavelengths are sensed as colors. Sources of
visible light are fires and hot glowing objects.
Questions you may have about visible
light include:
Detecting light
What makes visible light different than
the other electromagnetic waves--such as radio waves and
x-rays--is that light can be detected with your eyes.
This is due to the light causing chemical changes in
your retina. Light also can cause electrical and
temperature changes in some materials.
Visible light can cause chemical changes
in some materials. One example is how the sun will fade
the colors in your furniture. The film in a camera
detects light and turns it into the images you see in
photographs. Photographic film changes its chemical
characteristics according to how much light strikes it.
Light can also cause electrical changes
to occur in some materials. For example, a solar cell
creates electricity from light. The retina in your eyes
goes through chemical changes that creates electrical
impulses when light strikes it.
Another way to detect light is by
observing the rise in temperature of the object. The sun
shining on your skin or on some object will cause it to
heat up.
Characteristics
Some of the characteristics of visible
light are similar to that of all electromagnetic waves.
Light and all other electromagnetic
waves travel at the enormous speed of 186,000 miles per
second or 300,000 kilometers per second in a vacuum.
They all travel slightly slower through transparent
matter.
Light comes in a spectrum of wavelengths
that you can see. Each wavelength is sensed as a color.
The basic colors in the spectrum are:
-
Red
-
Orange
-
Yellow
-
Green
-
Blue
-
Indigo
-
Violet
These are also called the colors of the
rainbow. The way to remember the order of them is the
name: ROY G BIV.
When all the colors are combined, you
see them as white light.
Light will pass through some materials,
such as glass. Since the velocity of light is slower in
glass than in air, the light can be made to bend and
even be focused after passing through a glass lens.
Light also can be reflected by shiny
materials and absorbed by dark, rough materials.
Creating light
Visible light is created when an object
becomes sufficiently hot, as well as from some chemical
and electrical reactions.
The Sun is so hot that is gives off
visible light. Likewise, a fire is hot, as is the
filament in a light bulb.
As the burner on an electric stove gets
hot, it first gives off invisible infra-red light, then
becomes deep red and finally gives off orange or yellow
light when it gets hot enough.
Light from the Moon is actually light
from the Sun that is reflected off the Moon's surface.
Some chemical or electrical reactions
can create light. A good example of a chemical reaction
is the light from a firefly. A light-emitting diode
(LED) is an example of an electrical reaction causing
light.
Visible light is the part of the
electromagnetic spectrum of waves that you can detect or
see. Light's wavelengths are sensed as colors. Other
materials and devices can also detect light. Sources of
visible light are fires and hot glowing objects. |
