Exercise 3

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1

What are the following rules for its transport, cleaning, use, and storage of microscope?

Hold in upright position with one hand on arm, and the other supporting the base.

Special, grit-free lens paper is used to clean objective lens and ocular lenses. Use in a circular motion.

Always begin focusing process on the lowest power objective lens

Use the course adjustment knob only on the lowest power objective lens

Always use a coverslip with wet mount preparations.

When storing the microscope, always set the lowest power objective lens into position, lower the stage completely, wrap the cord and cover with dust cover.

Never remove any parts of the microscope.

2

Define Base of the microscope:

The foundation support of the microscope. Some have an inclination joints.

3

Substage light or mirror:

Positioned on the base of the microscope. The substage light passes directly upward through the microscope.

If a mirror is used, light must be reflected from a free-standing lamp.

4

Stage:

The platform the slide rests on while being viewed. Has a hole that permits light to pass through.

Spring clips: secure slides on the stage or mechanical stage.

5

Condenser:

Small substage lens that concentrates the light on the specimen. The condenser may have a rack and pinion knob that raises and lowers the condenser to vary light delivery.

6

Iris diaphragm lever:

arm attached to the base of the condenser that regulates the amount of light passing through the condenser.

Permits the best possible contrast.

7

Course adjustment knob:

Used to focus the specimen at the lowest-power objective

8

Fine adjustment knob:

Used for precise focusing once the coarse focus has been completed.

9

Head or body tube:

Supports the objective lens system which is mounted on a movable nosepiece and the ocular lenses.

10

Arm

Vertical portion of the microscope connecting the base and head.

11

Ocular (eyepiece)

Depending on the microscope, one or two, superior end of the head or body tube. Observations are made through the oculars with a magnification of 10X

12

What does magnification of 10X mean?

Increases the apparent size of the object by 10 times or ten diameters.

13

Where is the pointer attached?

One of the ocular lenses

14

Nosepiece:

Rotating mechanism that at the base of the head that the objective lenses are connected to.

15

What is the microscope an instrument of?

Magnification

16

How is this achieved?

Through the interplay of 2 lenses, the ocular lens and the objective lens.

17

What is the real image?

The image produced by the objective lens.

18

What is the virtual image?

The image produced by the magnification of the ocular lens of the real image.

19

What is the total magnification?

The magnification of the ocular lens multiplied by the magnification of the objective lens.

20

What is the limitation of the compound microscope?

Resolution. Objects closer than 0.2um will appear as one object.

21

What does resolution mean?

The ability to discriminate between two close objects.

22

What is the resolution of the human eye?

100um

23

What is the resolution of the compound microscope?

0.2um

24

What determines the resolving power?

The amount and physical properties of the visible light that enters the microscope.

The more light delivered to the objective lens, the greater the resolution.

25

What happens to the size of the objective aperture with increasing magnification?

It decreases.

26

What is the working distance?

The distance between the top of the specimen and the bottom of the objective lens when the specimen is in focus.

27

What does parfocal mean?

That a object should be in focus (or close) at the higher magnifications when in focus at the scanning magnification.

28

What happens to the working distance with increasing magnification?

It decreases.

29

What is the microscopic field?

The field of view through the microscope at a given magnification.

30

What is the formula to calculate the microscopic field at said magnification?

Diameter of field A X magnification A = Diameter of field B X magnification of field B.

31

What is the depth of the field?

the thickness of the plane that is clearly in focus.