microscope ppt

1. Simple & Compound Microsc
ope
Presented by-
MAAZ UL HAQ
C.L Gupta eye institute

2. Microscope
An optical instrument used for viewing very small objects, such a
s mineral samples or animal or plant cells, typically magnified sev
eral hundred times.
TYPES:
1. Simple microscope
2. Compound microscope

3. Simple Microscope
• A simple microscope is nothing but a single bicon
vex lens. It is referred to as magnifying glass
• The object to be viewed through a simple micros
cope is placed between the optic center and the
focus
• Image formed by a simple microscope is erect, vi
rtual and magnified.

4. 1. Linear magnification
Height of Image image distance
= =
Height of Object object distance
2. Angular magnification
Angle subtended at the eye by the image formed at the distance of distinct vision
Magnifying Power =
Angle subtended at the eye by the object formed at the distance of distinct vision

5. Magnifying Power of a Simple Microscope
• The magnifying power or angular magnification of a microscop
e may be defined as the:
– Ratio of the angle subtended at the eye by the image formed at the distanc
e of the distinct vision to the angle subtended by the object when placed a
t the distance of the distinct vision.

6. The ray diagram shows that the image of the object AB is
formed at A1B1. A1B1 is formed at the least distance of
distinct vision.
The figure shows that the
angle A1OB1 subtended at
the eye by the object in
the position A1B1 is
greater than the angle
AOB subtended by it in
the position AB. From this
it is clear that the eye
estimates the angle
subtended by an object
on it and not the linear
size of the object.

10. Uses:
• A simple microscope is used as a magnifying glass. It cannot be
used to observe very tiny objects like bacteria and cells becaus
e of its low magnification.

11. COMPOUND MICROSCOPE
It is an optical device used to see highly magnified image of tiny objects.
Construction:
It consist of two convex lenses of short focal length arranged co-axial at the
free end of tube, at a suitable fixed distance.
Objective Lens:
It is a convex lens of very short focal length fo and small aperture, kept near
the object.
Eye piece:
It is also a convex lens of comparatively larger focal length fe and larger aper
ture kept near the eye

12. Optics of Compound Microscope
• The object AB is placed at uo slightly
larger than the focal length of objective
lens.
• The objective lens forms a real, inverted
and magnified image A’B’ of the object AB
on the other side of lens.
• The distance between the objective and
eyepiece is so adjusted that the image
A’B’ lie within the focus of eyepiece.
• This image A’B’ acts as an object for
eyepiece.
• The eyepiece E form a virtual and
magnified final image A”B” which is
inverted to object.

13. Magnifying power of a compound Microscope
Magnifying power =
The ratio of the angle subtended at the e
ye by the final virtual image, to the angle
subtended at the eye by the object
Where ,
β = angle subtended at the eye by final image
α = angle subtended at the eye by object.
h’ = height of image, h = height of object
Ue = Object distance from eye piece, D = least distance of distinct vision
mo = Magnification of Objective lens, me = magnification of Eyepiece lens
tanθ=perpendicular /
base

14. • The eye piece acts as a simple microsc
ope.
where D = distance between eye piece to final image a
nd fe = focal length of eye piece.
As uo = -fo vo = L =Length of micros
cope tube.