What is image?
An image is anything that you
can see; in terms of lenses and
mirrors, an image is a
reflection in a mirror, or the
altered picture of the world
you see when looking through
Do all lenses and mirrors produce images?
Do they all produce the same kinds of
images? If not, what is different about them?
The lenses and mirrors produce many
different kinds of images. They can make
things appear bigger, smaller, upside-down,
inverted left-to-right, or combinations of
In scientific field image is a reproduction of an object formed by a
lens or mirror.
There are two types of images:
• Real Image: formed when light rays from an object, after
passing through a convex lens or reflecting off a concave mirror,
converge at a point some distance from the instrument. If a
screen is placed at the point at which the light rays converge, a
real image of the object will appear on the screen.
• Virtual Image: It gets its name from the fact that it exists only in
the eye of the viewer when he or she looks through a lens or into
a flat or convex mirror. These instruments cause light rays from
an object to diverge. A viewer looking at an object through one
of these instruments traces the diverging rays back to the place
beyond the instrument where they appear to be originating from.
At this point where the imaginary rays converge, the viewer sees
an image. This is why virtual images appear to come from beyond
the lens or within the mirror.
cannot be projected
like real images.
Rather, they are seen
when viewing objects
through hand lenses,
telescopes, or when
viewing an object in
a standard mirror.
Any lens or mirror may form a virtual image. However, only a
convex lens and a concave mirror can be used to form real images.
This is because only these instruments cause light rays to converge.
To form a clear real image, a screen must be placed a certain
distance (focal distance) from the lens or the image will be blurry or
This is different from the virtual image we see when looking
through a lens or into a mirror, in that our eyes automatically focus
the virtual image no matter what the distance between us and the
lens or mirror.
A real image of a single reflection is always inverted up-and-down
and left-to-right because it is formed where light rays converge.
A virtual image, however, may or may not be inverted, depending
on the shape of the lens or mirror.