Microscope - Wave Optics, Physics, Class 12 Video Lecture

microscope
you
in 1665 Robert
the existence of cells he coined the
word cells while observing a thin slice
of cork under his primitive microscope
the portrait of Robert Hooke a picture
of his microscope and the cells as
seen under his microscope are shown here
in 1674 Anton Wan leeuwen Hawk improved
robert hooke's microscope and discovered
free cells in the form of bacteria the
portrait of Anton Juan lumen hawk and a
picture of his microscope are shown here
in 1678 antoine lumen hawk discovered
sperm cells of humans dogs rabbits frog
fish and insects
in 1831 Robert Brown discovered and
named nucleus in plant cells
in 1838 matthias jakob schleiden
proposed that all plants consist of
cells
in 1839 je Purkinje gave the term
protoplasm for the living fluid present
in the cell Theodor Schwann
independently asserted that all plants
and animals consists of cells he
established the basis of cell theory the
pictures of plants and animal cells are
shown here
in 1855 our work out to find the cell
theory by presenting the idea that cells
arise out of pre-existing cells
in 1866 heckle established that nucleus
plays a role in storing and transmitting
hella jittery characters shown below are
the portrait of heckle and the structure
of the nucleus
in 1932 null and Ruska of Germany
designed the first electron microscope
it was in 1940 that the electron
microscope was invented this is a
picture of the electron microscope
parts of a compound microscope here is a
label diagram of compound microscope IPS
also called the ocular lens lies close
to the eye body tube is attached to the
upper end of the limb can be moved up
and down with help of a rack an opinion
has an eyepiece at its upper end a
revolving nose and two or three
objectives at the lower end objective
this lens lies close to the object stage
it is square in shape and is fixed to
the stage with two clamps to hold the
slide diaphragm or condenser it is
present under the stage to regulate the
amount of light entering the microscope
mirror this is fixed at the lower most
part of the limb it's plane surface is
used to direct light over the object
when seen through the lower part lens
its concave surface is used to direct
light over the object when seen through
the high part lens course adjustment
this is for focusing with low power lens
fine adjustment this is for focusing
with high power lens arm is also called
the limb and this holds the body tube
inclination joint this is for adjusting
the angle of inclination of the arm
condenser adjustment is for the
adjustment of the diaphragm or condenser
foot the microscope is built around a
basal foot
path
light as shown in the diagram the light
falls on the mirror and gets reflected
it's plain surface is used to direct
light over the object when seen through
the low part lens its concave surface is
used to direct light over the object
when seen through the high-powered lens
this light passes through the condenser
which regulates the amount of light
entering the microscope then the light
pass through the objective lens then
through the field lens and then through
the eyepiece
cells as seen under the microscope shown
here are the cells in the onion peel the
blood cells the structure of the leaf
and the cells in the cheek as seen under
a compound microscope
electron microscope the electron
microscope was invented in the year 1940
here is a label diagram of an electron
microscope it consists of an insulator
electron gun binocular viewer a photo
plate and a control panel
comparison between a compound and
electron microscope source of
illumination is visible light source of
illumination is a narrow beam of
electrons glass lenses are used
electromagnetic lenses are used not
enclosed in a vacuum tube enclosed in a
vacuum tube fluorescent screen or
photographic plate is not used
fluorescent screen or photographic plate
is used magnifies up 2500 times
magnifies up to a hundred thousand times