Video Transcript
The figure shows a microscope. Choose the letter that indicates
the position where the slide, with the specimen, is placed for viewing.
To answer this question correctly,
let’s take a look at the parts of the microscope labeled in this diagram and review
how the microscope is used to examine a specimen.
Microscopes allow us to see
organisms that are too small to be seen by the naked eye. They make the object look bigger by
passing light from the object through magnifying lenses, so we see a larger
image. But how do we use a microscope to
examine a specimen?
First of all, the specimen needs to
be placed on a glass slide. The slide is then placed on the
stage, labeled D here, and held in place by the stage clips. Light is then emitted from the
light source, labeled B, below the specimen. The light passes through an
adjustable apparatus below the stage, called the diaphragm or iris. This diaphragm adjusts the
intensity of the light getting through to the specimen. The light then passes through the
specimen on the slide and into the first of two magnifying lenses. As it is the lens closest to the
specimen, or object, it is called the objective lens.
There are usually three or four
objective lenses of different powers on a revolving nosepiece attached to the head,
here labeled C. As the light rays pass through the
objective lens, a magnified image of the specimen is formed. The light from the image then
passes through the second of the lenses found in the eyepiece, labeled A. So it is called the eyepiece
lens. As the light passes through the
eyepiece lens, the image is magnified again to form the final image. The final label on this diagram is
E, the base, which provides a firm, heavy platform, enabling us to use the
microscope.
Now that we have reviewed the parts
of the microscope and how a microscope is used to examine a specimen, we can return
to our question. It asks us to choose the letter
that indicates the position where the slide with the specimen is placed for
viewing. We now know the correct answer is
the stage, which is represented by letter D.
