The Microscope: Its Parts and Their Functions
Ocular (eyepiece)—the lens you
look through; it magnifies the
object (ours is 10x).
Coarse adjustment knob—moves
the body tube up and down in large
movements to focus the image;
start with this knob when focusing
with the low or medium power
objective lens in place.
Fine adjustment knob—moves the
body tube in small movements
to “fine tune” or sharpen the focus;
use only this knob when focusing
with the high power objective lens
in place.
Arm—acts as a
handle; supports the
body tube.
Stage clips—hold the
slide in place on the
stage.
Body tube—maintains the proper
distance between the ocular and
objective lenses (the focal length);
keeps light from scattering as it
goes up through the lenses;
moves up and down when
focusing.
Revolving nosepiece—holds
the objective lenses; rotates to
change the lens (lens must
click into place).
Objective lenses—lenses at
the base of the body tube;
they magnify the object;
ours has 3 lenses (low = 4x;
medium = 10x;
high = 40x).
Stage—supports the
slide; has a hole in the
middle to allow light to
pass through.
Diaphragm—controls the
amount of light going through
the object and up the body tube.
Mirror—bounces light up
through the diaphragm, the
stage, the object, and
into the two lenses.
Base—supports the
entire microscope.