Biology
, Overview
AS A2
Chapter 1-11
Chapter 12-19
I
Syllabus :
https://
www.cambridgeinternatio
nal.org/Images/
:
554607-2022-2024-
&
S
syllabus.pdf
.'
, microscopy
magnification size &
:
image ↳ wavelength
actual size resolution ↓
Light colours
↳ Light with
largest wavelength red (200nm)
-
↳
Light with smallest wavelength -
blue (400nm)
With
↳ magnification , resolution is half the
wavelength
Electron microscope [0 Sun >6son
.
i
↳ uses electrons
↳ has shorter wavelength
↳ can be controlled using magnets
function in vacuum
↳ can
only
↳ false
coloring can be done by
computer
Y Y
SEM TEM
formed to examine
↳ image by e- ↳ used thin
reflected from back slices of tissue/cells
of the
Object
3D
↳ max
magnification = 1 , 000 ,
000
↳
images ↳ Resolution can
go down
Typical magnification
↳ = x20
, 000
to 0 .
5 m
↳ Resolution less than TEM
ght .
m electron m .
·
light used · beam of e-used
· resolution
. 200 ·
resolution -0 S .
·
less expensive ·
more expensive
-x 1500 x500000
·
magnification ·
max
mag . -
· medium-air · medium-vacumm control
·
focuses light with lens ·
focuses by electromagnetic
Alive or dead specimen Dead specimen
· ·
, >
- conveiron
, Overview
AS A2
Chapter 1-11
Chapter 12-19
I
Syllabus :
https://
www.cambridgeinternatio
nal.org/Images/
:
554607-2022-2024-
&
S
syllabus.pdf
.'
, microscopy
magnification size &
:
image ↳ wavelength
actual size resolution ↓
Light colours
↳ Light with
largest wavelength red (200nm)
-
↳
Light with smallest wavelength -
blue (400nm)
With
↳ magnification , resolution is half the
wavelength
Electron microscope [0 Sun >6son
.
i
↳ uses electrons
↳ has shorter wavelength
↳ can be controlled using magnets
function in vacuum
↳ can
only
↳ false
coloring can be done by
computer
Y Y
SEM TEM
formed to examine
↳ image by e- ↳ used thin
reflected from back slices of tissue/cells
of the
Object
3D
↳ max
magnification = 1 , 000 ,
000
↳
images ↳ Resolution can
go down
Typical magnification
↳ = x20
, 000
to 0 .
5 m
↳ Resolution less than TEM
ght .
m electron m .
·
light used · beam of e-used
· resolution
. 200 ·
resolution -0 S .
·
less expensive ·
more expensive
-x 1500 x500000
·
magnification ·
max
mag . -
· medium-air · medium-vacumm control
·
focuses light with lens ·
focuses by electromagnetic
Alive or dead specimen Dead specimen
· ·
, >
- conveiron
