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Por la ley de refracción obtendremos la siguiente ecuación:
Poniendo esto en la primera ecuación tenemos:
n 1 = n 2 x sen ( α−β ) = (sen φ x cos β - cos φ x sen β )
n 2 ²x (1-cos² β ) = sen² i
n 2 ²- n 2 ² x cos ² β = sen² I
cos β =
n 1 = sen φ x
El ángulo de refracción φ y el índice de refracción n 2 del prisma son conocidos, luego
al conocer el ángulo crítico i, podemos conocer en índice de refracción de la muestra.
4. ESPECIFICACIONES TÉCNICAS
Refractómetro ABBE Modelo 325
Rango de medida
Indice de Refracción
º Brix
Precisión de las medidas
Indice de Refracción
º Brix
Escala del termómetro
Temperatura de trabajo
Medidas exteriores
Peso
Suministro eléctrico
Pág. 5
Manual de instrucciones 50325XXX
CASTELLANO
n 1 xsen90º= xsen α
n 2 xsenß = sen i
φ = α + ß
α = φ - ß
n 2 ²x sen² β = sen² i
n 2 ²-sen² i
n 2 ²
- cos φ− sen i
n 2 ²-sen² i
1´3000 a 1´7000
0 a 95%
± 0´0005
± 0´25
0 - 100º C
0 - 80º C
90 x 140 x 230 mm
2.6 Kg
220V±10%.50Hz
Revisión 2 de Diciembre-03
Turning the refraction index adjustment knob (1.11) look for light and dark field divi-
sory line, then turn knob (1.10) to adjust the dispersión in a way this line is seen without
any colour and as clear as posible. Once you have done this, turn the knob (1.11) again to
move divisory line up to the middle of both crossed lines.
The value in the bottom scale tells us the accurate liquid refraction index. If the scale
is not lighted enough, turn the condenser (1.9) towards light focus .
b) To test transparent solids
Solid to be measured must be smooth and polished faced.
Put one or two naphthalene bromide drops on the refraction prism surface. Clean all
the tested object surface properly to get the best contact.
When observing through the eyepiece, search for the divisory line between light and
dark coloured fields, and do as the instructions in the previous case.
c) To test translucent solids
The object to be measured must be smooth and polished faced.
Put one or two naphthalene solid and clean solid surface to place it on the refracting
prism. Open the reflecting mirror (1.6) and adjust to most appropriate angle, using it as
incidence surface for measuring.
Reading meted is the same as previous cases
Picture 4
d) To measure sugar concentration in sugary liquids
0
10 20
The procedure is similar to liquid samples but the reading
can be done on a Brix scale (larger scale 0- 95%) reading directly
the sugar concentration in the liquid.
1.330
1.340
e) Refractive index estimation at different temperatures
Insert the thermometer into its socket (1.7), connect the thermostat to the prepared
connectors (1.8) and (1.13) for bottom prism and (1.12) for top prism, thanks to the ther-
mostat temperature can be read in the ranges required. Before each reading, wait a cou-
ple of minutes to stable the temperature.
6. MAINTENANCE
To ensure accuracy and to avoid instrument damage, please, pay attention to your
refractometer maintenance.
Follow the instructions and warnings relating to this manual.
You should have this manual always by hand, so that any person can consult it.
Preserve the balance from heavy shocks. Look for a dry place away from dust, direct
sun beams or air flows. Since it is a precision instrument, it should be handled carefully.
For security never disconnect it by pulling the cable.
Never remove any of its mechanical components. In addition to losing the warranty, it
could also lead to a faulty performance of the balance.
It must be kept in a dry and well ventilated room to preserve optical items from humi-
dity and mild.
If you deal with corrosive liquids, you must clean all the instruments immediately to
prevent them from rust damages you should include in this list optical and mechanical
parties and also painted surfaces.
After each use, you must clean the refractive prisms with a non fuzz gauze, use alcohol or water.
Version 2 December-03
Instruction manual 50325XXX
ENGLISH
Page 16
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