Microscope
The microscope is a tool that is used to view small specimins.
The specemin is magnified so that we can see the different parts
of it. A microscope consists of an eyepiece which is attached to
an objective, and a plate. The plate holds the specimin, and there
is either a light source or a mirror under the plate. The mirror
serves the purpose of the light source, because by moving it, light
from the room can be sent into the microscope.
The Case 4 situation is used with the microscope. The object
is placed between f and 2f. The total magnification is determined
by the product of the magnification of the eyepiece and the magnification
of the objective. The magnification of the eyepiece and the magnification
of the objective must be calculated separately. There are two basic
equations involved in finding the magnification. The first is 1/f=1/di
+ 1/do, and the second is di/do
= si/so = magnification. For our purposes,
the distance to the image for the eyepiece will be 25 cm, which
is the near point for a normal eye. In a problem, another variable
must be given in order for you to calculate anything. For instance,
they might give the magnification, the focus length, or the length
of the barrel of the microscope. In the case of the latter, keep
in mind that the distance to the image for the objective added to
the distance to the object for the eyepiece will equal the barrel
length.
Example:
A microscope with a barrel length of 20cm has an eyepiece
with an objective with a magnification of 10. The objective’s focus
is 0.5cm. What is the total magnification of this microscope?
Answer:
Barrel
length: 20cm
Eyepiece
magnification: 10
Objective’s
focus: 0.5cm
di
for eyepiece = 25cm
Eyepiece
Magnification = di/do
10 = 25/do
do = 2.5cm
Objective
di = barrel length – do(eyepiece)
di = 20 – 2.5
di = 17.5cm
1/f = 1/di + 1/do
1/0.5 = 1/17.5 + 1/do
do = 0.5cm
Magnification = di/do
Magnification = 17.5/0.5
Magnification = 35
Total
Magnification
MT = Meyepiece x Mobjective
MT = 10 x 35
MT = 350
Therefore
the total magnification for this microscope is 35
Visit
in the fun section: How to Make
a Microscopie
|
The Optics Course
Movie Projector