Topic: Microscope
Aim: How can we measure a cell using a
microscope?
Do Now:
1. Copy the aim onto your notes sheet.
2. Complete Microscope Check pink sheet
3. Take out a piece of loose-leaf for today’s notes.
HW: Cells and Cell Processes Exam Review Sheet
(BOTH SIDES)
1. Where should the microscope be
safely placed?
• On a tabletop or other flat surface.
2. Why is the lowest power
objective used first?
• It provides a larger field of view.
LOW
HIGH
Ruler observed
under low power
LARGER FIELD OF
VIEW
Ruler observed
under high power
SMALLER FIELD
OF VIEW
3. Identify the objective that gives
a larger field of view.
• Low power
LOW
HIGH
4. Identify what occurs to the field
of view when switching from low to
high power.
• The field of view decreases.
• The amount of light decreases.
5. Identify the part that used to focus
the slide when using the 4x and 10x
objectives.
• Coarse adjustment
6. Identify the part that used to focus
the slide when using the 40x objective.
• Fine adjustment
The diagram represents a
cell in the field of view of a
compound light microscope.
In which direction should
the slide be moved on the
microscope stage to center
the cell in the field of view?
1. toward A
2. toward B
3. toward C
4. toward D
Units to measure cells
• Micrometers/Microns
• µm
• 1mm = 1000µm
Cells are so
small that
even a cluster
of these cells
from a mouse
only
measures
50 microns.
The human ovum
is typically
around between
120 to 150
micrometers
which is the
largest cell in the
human body. It is
visible to the
human eye under
a microscope.
The head of the
sperm is on
average 5 to 6
micrometers. The
flagellum is up to
50 micrometers
long.
Paper thickness =
about 150 µm
Human hair diameter =
80-100 µm
SHRIMP EGGS
mm  um
• Move decimal three places to the RIGHT
3.2 mm = ? µm
3. 2 0 0
3200 µm
Are there SI units smaller than micro????
"nano-" = 1/1,000,000,000 (billionth)
"pico-" = 1/1,000,000,000,000 (millionth of a
millionth, "micro micro-")
0.7634mm = ? µm
0.7 6 3 4 
763.4 µm
um  mm
• Move decimal three places to the LEFT
789 µm = ? mm
7 8 9.
.789 mm
53.6 µm = ? mm
0 5 3. 6 
.0536 mm
1.
1mm
3.2mm =
3200 µm
•Field of view =
2.
500um
1mm = 1000um
3.
1000um
2000/2 = 1000
2 mm =2000um
4.
500um
250um
1000um
5.
1000um
500um
2000um
6.
500um
250um
125um
1000um
7.
2500um
1250um
625um
5mm =
5000um
8.
1000um
5mm = 5000um
9.
1000um
7000um
10.
400um
2000um
Let’s summarize:
1. Identify the units used to measure cells.
2. Which way do you move the decimal
when converting from mm to um?
3. Which way do you move the decimal
when converting from um to mm?
4. Describe the two procedures that must be
followed before switching to high power.
5. Explain what happens to the amount of
light in your field of view when switching
from low to high power.
Determine the length of each cell in um.
500um
Diameter = 1mm
1000um
= 500um
1000um
500um
Diameter = 2000um
= 500um
Determine the length of each cell in um.
500um
Diameter = 1000um
1000/6
= 166.7um
1000um
Diameter = 2mm
= 2000um
1. Which way should
700um
1400um
you move the slide to
center the cell in the
350um field of view?
Move the slide to the
right (towards B)
2. Determine the
approximate length of
the cell.
a.
b.
c.
d.
300um
500um
700um
1000um