Q: If the field diameter under the 4x objective is 4 mm, what is the estimated field diameter under the 40x objective? (Assume the ocular lens is 10x and the field diameter is inversely proportional to the total magnification.)

$$\frac{4\ \text{mm} \times 40}{400} = 0.4\ \text{mm}$$

Q: If a specimen extends across half the field diameter under a 10x objective lens, and the field diameter is 2 mm, what is the estimated size of the specimen?

$$\frac{2\ \text{mm}}{2} = 1\ \text{mm}$$

Q: A student is measuring a specimen under a microscope. The field diameter is 1.5 mm, and the specimen covers one-third of the field. What is the estimated size of the specimen in micrometers ($$\mum$$)?

$$\frac{1.5\ \text{mm}}{3} \times 1000 = 500\ \mu\text{m}$$

Question 1

Which of the following best describes the correct initial steps for focusing a specimen using a compound light microscope?

Accepted Answer

Begin with the lowest power objective lens and use the coarse adjustment knob.

Question 2

A student is using a microscope with a 10x ocular lens and a 40x objective lens. What is the total magnification being used?

Accepted Answer

$$10 	imes 40 = 400$$

Question 3

If the field diameter under the 4x objective is 4 mm, what is the estimated field diameter under the 40x objective? (Assume the ocular lens is 10x and the field diameter is inversely proportional to the total magnification.)

Accepted Answer

$$\frac{4\ 	ext{mm} 	imes 40}{400} = 0.4\ 	ext{mm}$$

Question 4

Which part of the microscope should only be used with the lowest power objective lens to avoid damaging the slide or lens?

Accepted Answer

Coarse adjustment knob

Question 5

A specimen appears blurry under high power, but is clear under low power. What is the most likely reason for this?

Accepted Answer

The depth of field decreases as magnification increases, requiring finer focusing.

Question 6

Which of the following best explains why you should never use the coarse adjustment knob with the high power objective lens?

Accepted Answer

It can cause the objective lens to crash into the slide, potentially damaging both.

Question 7

If a specimen extends across half the field diameter under a 10x objective lens, and the field diameter is 2 mm, what is the estimated size of the specimen?

Accepted Answer

$$\frac{2\ 	ext{mm}}{2} = 1\ 	ext{mm}$$

Question 8

Which of the following statements about the relationship between magnification and field diameter is correct?

Accepted Answer

As magnification increases, field diameter decreases.

Question 9

What is the function of the condenser on a compound microscope?

Accepted Answer

It focuses light onto the specimen.

Question 10

A student is measuring a specimen under a microscope. The field diameter is 1.5 mm, and the specimen covers one-third of the field. What is the estimated size of the specimen in micrometers ($$\mum$$)?

Accepted Answer

$$\frac{1.5\ 	ext{mm}}{3} 	imes 1000 = 500\ \mu	ext{m}$$

Question 11

Which of the following best defines 'resolution' in microscopy?

Accepted Answer

The ability to distinguish two points as separate entities.

Question 12

Why is it important to use lens paper and not regular tissue to clean microscope lenses?

Accepted Answer

Regular tissue can scratch the delicate lens surface.

Question 13

Which of the following is NOT a correct handling instruction for a compound microscope?

Accepted Answer

Swing the microscope by the arm only when transporting.

Question 14

If you switch from a 10x to a 40x objective lens, what happens to the working distance?

Accepted Answer

It decreases.

Question 15

A student is viewing a specimen under the 4x objective and wants to switch to the 40x objective. What should the student do before switching objectives?

Accepted Answer

Center the specimen in the field of view.

Question 16

Which of the following best describes 'depth of field' in microscopy?

Accepted Answer

The thickness of the specimen that is in focus at one time.

Question 17

If a microscope's field diameter at 10x is 2 mm, and you switch to 40x, what is the new field diameter?

Accepted Answer

$$\frac{2\ 	ext{mm} 	imes 10}{40} = 0.5\ 	ext{mm}$$

Question 18

Which part of the microscope is responsible for moving the slide left, right, forward, and backward?

Accepted Answer

Mechanical stage control

Question 19

A student observes that the image is too dark under high magnification. What is the best way to correct this?

Accepted Answer

Increase the light intensity using the light control.

Question 20

Which of the following is the correct formula for calculating total magnification in a compound microscope?

Accepted Answer

$$	ext{Total Magnification} = 	ext{Ocular Magnification} 	imes 	ext{Objective Magnification}$$

Microscopy: Structure, Use, and Principles for Anatomy & Physiology (lab)

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