Microscopy

Question 1

Describe the parts
of a light
microscope.

Answer 1

Eyepiece lens
Objective lens
Stage
Specimen
Mirror
Course focus
Fine focus

Question 2

What is the
function of the
eyepiece lens?

Answer 2

You look through this lens to look at your
sample. This has often a magnification
factor of 10.

Question 3

What is the
purpose of the
objective lens?

Answer 3

Usually three to chose from: x5, x10 or x25.
The smallest is easiest to focus so try this
first.

Question 4

What is the
function of the
stage?

Answer 4

To hold the sample securely, often using
two metal clips.

Question 5

How do you
prepare the
specimen?

Answer 5

Usually placed in a drop of water or stain on
a microscope slide under a very thin glass
cover slip.

Question 6

What is the
function of the
mirror?

Answer 6

Reflects light up to through the sample, lens
and into your eyes.

Question 7

What is the
function of the
course focus?

Answer 7

Quickly and easily moves the stage up and
down to focus on the sample.

Question 8

What is the
function of the
fine focus?

Answer 8

Sensitively and slowly moves the stage up
and down to sharpen the image.

Question 9

How do you
calculate the total
magnification when
using a light
microscope?

Answer 9

Magnification of eyepiece lens x
magnification of objective lens.
E.g. eyepiece lense x4
Objective lens x10
Total magnification = 4x10 = x40

Question 10

How do you
calculate the actual
size of the object?

Answer 10

Image size/magnification.
The image size is given in μm.
Work out the image size in mm. Divide by
magnification. Convert to μm: multiply the
answer in mm by 1000.

Question 11

What is an electron
microscope?

Answer 11

A microscope that uses electron beams
instead of light rays to give a higher
magnification.

Question 12

What is resolving
power?

Answer 12

How much an instrument can distinguish
between two points. The higher the
resolving power the more detail is shown

Question 13

What is resolution?

Answer 13

The ability to distinguish between two
points.

Question 14

What is the
advantage of
electron
microscopes over
light microscopes?

Answer 14

Electron microscopes have a higher
magnification and resolving power than a
light microscope which means they can
be used to study cells in much finer
detail. This has enabled biologists to see
and understand many more sub-cellular
structure.