Page 222 - Physics_Form_2

Physics for Secondary Schools

objective lens. This lens forms and assures continuous alignment of the optics. A
a real, inverted and magnified stage is used for holding the object to be viewed,
image of the object. The image and the base supports the whole structure of the
formed by the objective lens microscope. Figure 6.3 shows important parts of
serves as the object for the a compound microscope.
second lens, which is known Eye piece
FOR ONLINE READING ONLY
as the eyepiece. The eyepiece
functions as a simple microscope
to produce the final image, which Coarse
is enlarged and virtual. adjustment Body tube
knob
A compound microscope has a Fine Revolving
revolving nose piece that allows adjustment nose piece
the user to change the objective knob Objective lens
lens according to needs. The
compound microscope also Specimen stage
consists of the lighting system, Inclination Condenser
which may be called the joint
illumination system. It consists Mirror
of a light source, which can be Base
an electric bulb, a light-emitting
diode (LED) or sometimes Figure 6.3: A compound microscope
natural sunlight. There is also
a mirror and a condenser which Mode of action of a compound microscope
help to transmit light through an A compound microscope works by using the
object for viewing. On the other principle that an image formed by one optical
hand, the compound microscope element can serve as the object for the second
has a focusing system. optical element. That is, an image formed by

the objective lens is used as the object for the
This system is made of coarse eyepiece. The object to be viewed is placed just
and fine adjustment knobs, which beyond the first focal point F of the objective
o
are essential for moving the lens, which forms a real and enlarged image I as
objective lens away or towards illustrated by Figure 6.4. 1
the object in searching for a clear
image. The system also has the In a properly designed compound microscope, the
inclination joint, which helps image formed by the objective lens lies just inside
in tilting the microscope for a the focal point F of the eyepiece. The eyepiece
e
comfortable view. Other parts of (or ocular) acts as a simple magnifier and forms
a compound microscope include a final virtual image I . The position of I may
2
2
the body tube, which separates be anywhere between the near and far points of
the objective and the eyepiece the eye.

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Student’s Book Form Two

Physics Form 2 Final.indd 216 25/10/2025 10:28