Microscopy

Question 1

Which part of the light microscope collects light passing through the specimen and produces a magnified image?

Answer 1

Objective lens

Question 2

Which lens in a light microscope does not magnify the image?

Answer 2

Condenser lens - this is below the stage and focuses the light onto the specimen.

Question 3

What is the proper name for the lens at the top of the microscope?

Answer 3

Eyepiece lens

Question 4

Which light microscope lens will tend to produce the greater magnification?

Answer 4

Objective lens

Question 5

What is the difference between magnification and resolution?

Answer 5

Magnification describes how much larger the image produced is than the real specimen. e.g. a 1mm specimen magnified 50x appears in the image as 50mm. Resolution describes the sharpness and clarity of the image; how easy it is to distinguish between two separate points within the image. Think about enlarging low quality digital images and the pixelation you see - you have magnified the image but the resolution has decreased.

Question 6

What are the two forms of radiation used in microscopy?

Answer 6

Light and electrons

Question 7

What is the study, within Biology, of the preparation of specimens for examination using microscope?

Answer 7

Cytology

Question 8

Which unit of measurement is 1000x smaller than a mm?

Answer 8

micrometer (µm)

Question 9

How many micrometers are there in 14mm?

Answer 9

14,000 µm

Question 10

How many µm in 3.6m?

Answer 10

3,600,000µm

Question 11

Which unit of measurement is smaller, micrometers or nanometers?

Answer 11

Nanometers (nm)

Question 12

How many nanometers are in 7mm?

Answer 12

7,000,000nm

Question 13

How many nanometers are in 46µm?

Answer 13

4,600nm

Question 14

Why is the letter “µ” used?

Answer 14

“µ” is the greek letter for m, pronounced “mu”. It is used because micrometers starts with an m, but the written shorthand (µm) distinguishes it from millimetres (mm)

Question 15

What is the maximum resolution of a light microscope?

Answer 15

200nm

Question 16

In light microscopy, what do we see when structures are within 200nm of each other?

Answer 16

We only see one object - the two points cannot be resolved.

Question 17

How do we calculate the magnification of a microscopy image?

Answer 17

MIA

Magnification = Image size ÷ Actual size

e.g. a 2mm image of a structure that is 5µm wide

2000 ÷ 5 = 400x magnification

(remember to always ensure both numbers are in the same unit - convert if necessary!)

Question 18

What is the magnification of an object whose actual size is 23nm and whose image size is 4.6mm?

Answer 18

200,000x

4.6mm x 1,000,000 = 4,600,000nm

4,600,000nm ÷ 23nm = 200,000