# THE MICROSCOPE(7)

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```					                              THE MICROSCOPE

OBJECTIVE/RATIONALE

The use of microscopes is an integral part of the laboratory setting. The student will care
for a compound microscope and use all of the objectives.

TEKS 1A, 1B, 1C                               TAKS ELA 1, 3, 4
Mathematics 1, 10
Science 1, 2

National Science Education Standards A9-12; E9-12; G9-12
National Health Care Skills Standards .01, .04, .07
National Curriculum Standards for School Mathematics S1; S2; S4

KEY POINTS

I.   Introduction
a.   Compound microscopes contain a number of lenses, usually 10x in the
eyepiece and 10x, 40 or 45x, and 100x (immersion oil) lenses in the
objectives. The microscope magnification is calculated by multiplying the
eyepiece magnification by the objective magnification. For example:
10x (eyepiece) x 100x (objective) = 1000x
The specimen is therefore magnified 1000 times the normal eyesight.
b.   Definitions
1.    Resolution: the microscopes’ ability to distinguish between two
points that are close together. The resolving power is expressed in
length.
2.    Oil immersion objective: this objective uses immersion oil to allow
light to pass through it the same way light passes through the glass
slide. The oil decreases the bending of the light rays allowing more
light to pass directly to the specimen.
3.    Binocular: a microscope with two eyepieces as opposed to one
eyepiece. Most hospital laboratories use binocular microscopes.
II.   Components of the Microscope
a.   eyepiece
b.   arm
c.   base
d.   binocular tube
e.   revolving nosepiece
f.   objective lens
g.    mechanical stage
h.    stage clips
i.   iris diaphragm
l.   lamp
m.    bulb
n.    on/off switch
III.   The Microscope
a.    Lower the stage to its lowest position using the coarse focusing knob.
b.    Place the slide on the stage and place the stage clips on top of the slide to
hold the slide in place.
c.    Use the coarse adjustment knob to focus on the slide, and then use the fine
adjustment knob until the object is in sharp focus.
d.    Adjust the light intensity by raising and lowering the condenser to give the
best image.
e.    After focusing with the 10x objective, rotate the 40x objective into the
position over the slide. Use only the fine adjustment knob to obtain a sharp
image.
f.   Rotate the objectives so that there is not a lens directly over the slide.
Place one drop of the immersion oil on the slide. Slowly rotate the 100x
objective into position over the slide.
g.    USE ONLY the fine adjustment knob to focus on the specimen slide.
Adjustment of light intensity may be necessary.
h.    To change slides during the investigation, follow steps a through g.
i.   At the conclusion of the laboratory investigation, lower the stage to the
lowest position. Clean all lenses and place the 10x objective in position.
j.   Wrap the cord around the arm of the microscope and replace the dust
cover.
IV.    Care of the Microscope
a.    The microscope should always be carried by the base and the arm.
b.    The microscope cord should be wrapped around the arm of the
microscope.
c.    The microscope should always be covered with a dust cover to prevent
dust buildup on the lenses.

ACTIVITIES

I.   Complete the Microscope Exercise.

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Jun Wang Dr
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