3B Scientific Oscillation Tube - Manual

4
Instruction sheet
3B SCIENTIFIC® PHYSICS
U14328 Precision tube
9/03 ALF
®
The precision tube is used together with the Marriott
bottle U14327 to determine the adiabatic exponent c
P
/c
V
using Rüchardt’s method.
1. Safety instructions
• Handle the glass tube carefully. Do not subject to
mechanical stress or it may break.
• Make sure both glass tube and aluminium cylinder
are thoroughly clean because even the slightest
amount of dirt leads to increased friction.
• Do not drop the aluminium cylinder. Even the slight-
est deformation adversely affects the experiment.
2. Description, technical data
A precision glass tube supplied with rubber stoppers at
both ends and with an aluminium cylinder precisely en-
gineered to slip inside.
If the glass tube is held vertical with the bottom end
closed and the aluminium cylinder is allowed to slide
down inside it, the cylinder drops very slowly since there
is only a tiny gap around the sides for air to escape from
underneath. If the tube is rotated by 180°, the cylinder
behaves in the same manner since the pressure in the
upper part of the tube is reduced as the cylinder slides
down, and air can only get in to fill the space very slowly.
In the third situation, the cylinder is allowed to drop into
an open tube which is then immediately stoppered. The
cylinder then slows and oscillates up and down a few
times.
Dimensions: 600 mm x 16 mm Ø
inner
Aluminium cylinder: 15.2 g
2.1 Scope of supply
1 Precision glass tube
2 Rubber stoppers
1 Aluminium cylinder
3. Theory
Symbols used in the formula:
m:
Mass of aluminium cylinder
d: Inside diameter of precision tube
A: Cross-sectional area of precision tube
V: Volume of measuring flask
p
L
: Atmospheric pressure
p: Pressure in the bottle
g: Acceleration due to Earth’s gravity
n: Number of moles
R: Universal gas constant (8.31451 kJ/kmol K)
T: Temperature
T
s
: Period of oscillation
t: Time
c
p
: Specific heat at constant pressure
c
V
: Specific heat at constant volume
?:
c
P
/c
V
M: Natural frequency of oscillation
The state of an enclosed quantity of an ideal gas can be
uniquely expressed in terms of the quantities pressure p,
volume V and temperature T as follows:
1 Stand
2 Marriott bottle
3 3-way stopcock
4 Hand pump
5 Stoppers
6 Precision tube
7 Aluminium cylinder
1
2 3
4
5
6
7