Transcript PHYSICS EXPERIMENT Group 2 - Nitin Tokas

PHYSICS EXPERIMENT
Nikita Tokas (303/B/12)
Nitika Agarwal (305/B/12)
Nitin Saxena (306/B/12)
Of COE-2, Batch of 2012-16
Group 2
AIM
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To determine the resolving power of the telescope.
APPARATUS REQUIRED
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A telescope
A powerful source of monochromatic light
Variable rectangular aperture
Measuring scale
Micrometer microscope
Sheet of plate glass coated with a tin foil containing
two fine parallel lines
Telescope
Telescope is a device which is used to view distant
objects. Resolving power of telescope is the ability
of telescope to produce distinct images of two
nearby objects. It is defined as the reciprocal of the
least angular separation between two distant
objects, with the base of angle at the telescope,
such that the objects appear separated when seen
through telescope.
THEORY
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For a telescope fitted with a rectangular aperture, the
limiting angle of resolution  is given by:
 = OO’/u = /d
where
OO’ = distance between the two objects
u = distance of the object from objective of the telescope
 = wavelength of light coming from the objects
d = width of aperture( placed below the objective of
telecscope) for just resolution of the two objects
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The reciprocal of the limiting angle of resolution is the
resolving power.
EXPERIMENTAL SETUP
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SOURCE : http://www.scribd.com/doc/32219885/Resolving-Powerof-Telescope-by-Mr-charis
PROCEDURE
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The given double slit is fitted to a slit stand and place
closer to the sodium vapor source, such that the two
slits are clearly visible from the telescope.
Place the telescope at a distance of 1 meter from the
double slit and fix the micrometer eyepiece to the
objective of the telescope with its slit completely open.
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Observing through the telescope adjust the focus using
rock and pinion screw of the telescope so that the two slits
are clearly visible and decrease the width of the slit of the
micrometer eyepiece slowly till the two slits come closer
and closer to attain the just resolved position. Note the
readings of the micrometer eye piece.
Further decrease the width of the adjustable slit such that
the field of view becomes completely dark and note the
readings of the micrometer eye piece.
Repeat the 2nd, 3rd and 4th steps by increasing the
distance of the telescope in the steps of 10 cm and
calculate the value of width of the slit in just resolved
position.
OBSERVATIONS
  = 5500 Å
 00’ = 2 x 10-3 m
OBSERVATION TABLE
S.No.
DISTANCE BETWEEN
TARGET AND
OBJECTIVE
MINIMUM WIDTH OF
SLIT FOR
RESOLUTION
THEORITICAL
RESOLVING
POWER
PRACTICAL
RESOLVING
POWER
u (cm)
d(mm)
(d/)
(u/00’)
1
100
0.270
490.9
500
0.98
2
90
0.250
454.5
450
0.95
3
80
0.210
381.8
400
0.95
4
70
0.187
340.0
350
0.97
5
60
0.162
294.5
300
0.98
6
50
0.134
243.6
250
0.97
7
40
0.100
181.8
200
0.91
d/ :u/00’
CALCULATIONS
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Mean Theoretical Resolving Power = 341.01
Mean Practical Resolving Power = 350
Percentage Error
= |Theoretical R.P. – Practical R.P.| X 100
Theoretical R.P.
= 2.64 %
RESULT
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The expression for the resolving power of the
telescope fitted with a rectangular aperture has
been verified.
PRECAUTIONS AND SOURCES OF ERRORS
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The mechanical adjustments of the telescope must be
correct.
The plane of the target consisting of two bright linear
sources should be vertical and so also these sources.
The axis of the telescope should be horizontal and
should meet the target normally.
Due care must be taken while measuring the width of
the aperture and distance between two linear sources
with a microscope. Avoid back lash error during the
course of measurements made with it.
The screw attached to the variable width aperture
should be handled gently.
BIBLIOGRAPHY
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A Textbook of Practical Physics
By : Indu Prakash, Ram Krishna, A.K. Jha
www.google.com