Everything Life Sciences Grade 10

Part of the microscope Description

Ocular lens/ eyepiece - A cylinder containing two or more lenses.

• These lenses are held at the correct working
  distance.


• The ocular lens/eyepiece helps to bring the
  object into focus.
  Revolving nose piece The revolving nose piece holds the objectives in
  place so that they can rotate and can be changed
  easily.
  Objective The objective magnifies the objects.
  There are normally three objectives present:


• 4X magnification


• 10X magnification


• 40X magnification

Coarse adjustment screw The coarse adjustment screw is used for the initial

focus of the object. By moving the stage up and

down, bringing the object closer to or further

away from the objective lens.

Fine adjustment screw The fine adjustment screw is used for the final and

clear focus of the object.

Frame - A rigid structure for stability.

• The frame is supported by a U-shaped foot
  leading to the base of the microscope.
  Light source / mirror - Provides a source of light so that the object can
  be viewed.
  Diaphragm and condenser The diaphragm and condenser control the amount
  of light which passes through the slide.
  Stage - The microscope slide is placed here.


• The stage contains a clip or clips to prevent the
  slide from moving around.


• There is a hole in the stage which allows light
  through.

Table 3.1: The parts of a microscope.

NOTE:

The ocular, rotating nosepiece and objectives are held above the stage by the arm.

How to use a microscope correctly

1. When handling or carrying the microscope, always do so with both hands. Grasp the
   arm with one hand and place the other hand under the base for support.


2. Turn the revolving nosepiece so that the lowest power objective is in position.


3. Place the microscope slide on the stage and and fasten it with the stage clip(s).


4. Look through the eyepiece and adjust the diaphragm for the greatest amount of light.


5. While looking at the slide on the stage from the side, turn the coarse adjustment screw
   so that the stage is as close to the objective lens as possible. WARNING: Make sure
   you do not touch or damage the slide.


6. Slowly turn the coarse adjustment screw until the image comes into focus.


7. Now use the fine adjustment screw to move the stage downwards until the image is
   clearly visible.Never move the lens towards the slide.

Chapter 3. The basic units of life 65