by priyanka jakhar

1. Compound
microscopes
BY
Priyanka Jakhar

2. 1.Compound microscopes
•The term “compound” in compound microscopes refers to the microscope having
more than one lens.
•Devised with a system of combination of lenses, a compound microscope
consists of two optical parts, namely the objective lens and the ocular lens.
•Compound microscopes have a combination of lenses that enhances both
magnifying powers as well as the resolving power.
•Compound Microscopes are used for the study of structural details of a cell,
tissue, or organ in sections.
•A compound microscope can magnify the image of a tiny object up to 1000.
•The term compound means “multiple” or “complex”.
•The compound microscopes is consists of two lenses includes, the objective
lens (typically 4x, 10x, 40x or 100x) in a rotating nosepiece closer to the specimen,
and the eyepiece lens (typically 10x) in the binocular eyepieces.
Construction
A convex lens which help us to observe clearly an object (very small object) which
is brought close to eye. within least distance of distinct vision, is called Magnifying
Glass.

3. Objective lens -Objective lens of small focal
length and small aperture this lens is near to
the object.
Denoted by 𝒍𝒐 .
Eyepiece –Eyepiece an achromatic convex
lens a of a small focal length and small
aperture( greater than objective lens) this lens
is nearer to the eye.
Denoted by 𝒍𝒆 .
Cylindrical tube- Cylindrical tube long
cylindrical metallic tube carrying objective
lens at one end and at the other end of the
tube is fitted in a larger tube at the outer end
of the larger tube is fitted an eyepiece 𝒍𝒆 .
Eyepiece can moved forward and backward in
this tube by rack and pinion arrangement.

13. Working Principle of Compound Microscope
The compound microscopes are works on the principle that when a tiny specimen
to be magnified is placed just beyond the focus of its objective lens, a virtual,
inverted and highly
magnified image of the object are formed at the least distance of distinct vision
from the eye held close to the eyepiece.
•The object (AB) is placed at a distance slightly greater than the focal length of the
objective lens (u > f0).
•A real, inverted and magnified image (A’B’) is formed at the other side of the
objective lens.
•This image behaves like the object for the eye lens.
•The position of the eye lens is adjusted in such a way, that the image (A’B’) falls
within the principal focus of the eyepiece.
•This eyepiece forms a virtual, enlarged and erect image (A” B”) on the same side
of the object.
•A compound microscope has 50 to 200 times more magnification power than the
simple microscope.