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PHYS 3203
LABORATORY MANUAL
Kingdom of Saudi Arabia
Ministry of Education
Islamic University in Madinah
Department of Physics
قسم الفيزياء
2
Title of Experiment Experiment
Determination of Young’s modulus of a metal wire 1
Determination of specific heat of solids 2
Determination of the velocity of sound by using columns air 3
Measurement of the buoyancy force 4
Determination of the viscosity of viscous fluids 5
Measurement of the surface tension 6
Temperature measurement with a thermocouple 7
Determining of the focal length of a concave mirror and convex mirror. 8
Determining of the focal length of the converging and diverging lenses 9
Standing waves (Melde’s Experiment) 10
Refraction of Light ( Snell’s Law ) 11
3
EXPERIMENT 1: Determination of Young modulus of wire
Objects of the experiments
To investigate the elasticity of materials by showing that the stress is proportional to the strain.
To find Young’s modulus for given materials
Apparatus
(i) Universal Testing Machine (UTM) (ii) Weight (iii) Graph paper (iv) Scale (v) Screw
Gauge/micrometer
Introduction When a spring or a rubber band is stretched and released, they come back to their original size &
shape. This physical property of a material called ‘elasticity’. When subjected to external forces,
a solid body may deform. Then internal forces come into play and try to restore the body in its
original shape. When the deformation is very large, the body may be permanently deformed; for
example, if we try to stretch the rubber band to a very large extent, then it breaks after a certain
point and it gets permanently deformed. But in case of a spring the same magnitude of force
may not cause a permanent deformation. The breaking force can vary from material to material.
Similarly, the extent to which the shape of a body is restored when the deforming forces are
removed, varies from material to material. The property of the material that restores the natural
shape or resists the deformation is called the elasticity of a material. As a measure of the
stiffness of a material, the knowledge of elasticity of materials used in construction is important
in engineering designs.
Stress:
Stress is the external force acting on an object per unit cross-sectional area.
A
F=
Figure 1
For compression or tension, the normal stress s is the ratio of the force to the cross sectional
area.
Measures pressure. SI unit pascal Pa = N / m2 = kg / m s2
Strain The result of a stress is strain, which is a measure of the degree of deformation.
L
L =
Figure 2
4
Hooke’s Law Hooke’s law states that
“within the limit of elasticity stress is directly proportional to strain”
We call this proportionality constant the elastic modulus. The elastic modulus is therefore
defined as the ratio of the stress to the resulting strain:
Strain
StressElasticity=
For linear change StrainYStress =
Where Y is called Young modulus
Molecular Model of Stress and Strain To see how this linear stress-strain relationship comes about, let’s look at a solid metal wire on
the atomic scale. The metal atoms of the wire are bound together by electrical forces. The exact
nature of these forces is complicated but we can model the solid approximately as points (the
atoms) in a three-dimensional lattice, interconnected with springs. If we anchor one end of the
wire and stretch it out with a known force at the other end, each little spring aligned along the
length of the wire will stretch by the same amount since the same applied force is transmitted
uniformly to each. Although the stretch of an individual spring may be microscopic, there are a
lot of them and the sum of all of these teeny changes can produce a macroscopic change in the
length of the wire, that is, one that is measurable in a lab.
Just like a spring, for a certain range of applied forces, the wire obeys Hooke’s law. This means
that the change in length is proportional to the applied force. Also like a spring, when the
applied force is removed, the wire returns to its original length. If we go beyond that certain
range, if we exceed some maximum applied force, the wire or spring is permanently deformed
or it breaks. The only difference between a wire and a spring is that the magnitude of the stretch.
This stretching behavior is summarized in a stress-strain diagram such as the one shown in Fig.
3.
5
Figure 3: Typical tensile stress-strain curve for a metal. Of interest in this experiment is
the linear, or elastic, region.
As the stress is increased between points a and b on the graph, the stress-strain relationship for
the wire is linear and elastic. Between points b and c the behavior is still elastic but is no longer
linear. After point c, called the yield strength, the material enters the plastic deformation region,
which means that the stretch of the wire is permanent. (For example, if the wire is stressed to
point d on the graph and the stress is slowly decreased, the stress-strain curve follows the dotted
line instead of the original curve and there is a leftover strain when all stress is removed.) At
point e the wire reaches its breaking point. Differences in the shape and limits of the stress-strain
diagram determine whether a material is considered ductile or brittle, elastic or plastic.
Figure 4: Experimental Setup
6
Experimental Procedure
1. You are given a piece of wire hanging vertically in a sturdy frame, a kilogram mass
hanger attached to the end of the wire and a stack of kilogram masses.
2. The wire is connected to a bubble level and balancing micrometer, which allows you to
determine small changes in the length of the wire.
3. You record the initial length and initial diameter of the wire.
4. You then place different amounts of mass on the mass hanger and for each amount you
determine the cumulative change in length of the wire.
5. In the analysis you calculate and plot stress vs. strain.
6. From this graph you determine whether the stress on the wire remains in the linear
region.
7. You find a numerical value of Young’s modulus for the wire, and you determine the
material that composes the wire by comparing this experimental value to a table of
accepted values.
Metal
Y
(GPa)
lead 15.7
magnesium 41.8
aluminum-nickel alloy 64.7
cadmium 69.3
silver (hard drawn) 77.5
antimony 78.0
gold 78.5
brass 90.2
zinc 104.7
titanium 120.2
copper 129.7
platinum 166.7
nichrome 186
steel (hard drawn) 192.2
steel (annealed) 200.1
nickel 207.0
tungsten (drawn) 355.0
Table 1 Young's moduli of various metals.
7
EXPERIMENT 1: Determination of Young modulus of wire
Name: _________________________________ID: _______________________
Instructor: ________________________________________________________
Section: ___________________________Date:___________________________
Lab. Partners: ____________________________________________________
DATA AND ANALYSIS
Initial parameters of wire
Length L = ……………, radius r = ………….. Area a= πr2 = ……………..
Table for Stress and Strain
Mass (m) Kg Force (N)
F = mg
Stress
(N/m2)
A
F=
Change in
length ΔL
(m)
Strain
L
L =
Young
modulus
/Y = (Pa)
Draw the graph between stress and strain as shown in Figure 3. Calculate the young modulus
from the slope of graph.
Young modulus Y =……………………………………………..
Calculate the % error in your experiment. Use table 1 for accepted value of Y.
% error = ……………………………
8
EXPERIMENT 2: Specific Heat of Solids
Objects of the experiments
1. Mixing cold water with heated copper, lead or glass shot and measuring the mixture temperature.
2. Determining the specific heat of copper, lead and glass.
Apparatus
1 Dewar vessel
1 cover for Dewar vessel
1 copper shot, 200 g
1 glass shot, 100 g
1 lead shot, 200 g
1 school and lab. balance 610 Tare, 610 g
1 thermometer –10 0C to +110 0C
1 steam generator, 550 W / 220 V
1 heating apparatus
1 beaker, 400 ml
1 stand base, V-shape, 20 cm
1 stand rod, 47 cm
1 Leybold multiclamp
1 universal clamp, 0 … 80 mm dia.
1 silicone tubing int. dia. 7 × 1.5 mm, 1 m.
1 pair of heat protective gloves
9
Theory
The heat quantity ΔQ that is absorbed or evolved when a body is heated or cooled is proportional to the
change of temperature Δ and to the mass m:
cmQ= (I)
The factor of proportionality c, the specific heat capacity of the body, is a quantity that depends on the
material.
In this experiment, the specific heat capacities of different substances, which are available as shot, are
determined. In each case the shot is weighed, heated with steam to the temperature 1 and then poured
into a quantity of water that has been weighed out and that has the temperature 2. After the mixture has
been carefully stirred, the pellets and the water reach the common temperature M through heat exchange.
The heat quantity evolved by the shot
)(mcQ M −= 1111 (II)
m1: mass of the shot
c1: specific heat capacity of the shot
is equal to the heat quantity absorbed by the water
)(mcQ M 21222 −= (III)
m2: mass of the water
The specific heat capacity of water c2 is assumed to be known. The temperature 1 is equal to the
temperature of steam. The unknown quantity c1 can therefore be calculated from the measured quantities
2, M, m1 and m2:
10
Figure 2.1
11
Experimental setup
1. The experimental setup is illustrated in Fig. 10.2.
2. Mount the heating apparatus in the stand material.
3. Fill water into the steam generator, close the device cautiously, and connect it to the top hose
connection of the heating apparatus (steam inlet) with silicone tubing.
4. Attach silicone tubing to the bottom hose connection of the heating apparatus (steam outlet), and
hang the other end in the beaker. See to it that the silicone tubings are securely seated at all
connections.
5. Fill the sample chamber of the heating apparatus as completely as possible with lead shot, and
seal it with the stopper.
6. Connect the steam generator to the mains, and heat the shot for about 20−25 minutes in the
heating apparatus flowed through by steam.
12
Figure 2.2: Experimental setup
Procedure
1. Determine the mass of the empty Dewar vessel, and fill in about 180 g of water.
2. Mount the cover for the Dewar vessel and insert the thermometer or the temperature sensor
respectively.
3. Measure the temperature 2 of the water.
4. Open the cover of the Dewar vessel and shift it aside; leave the mesh for samples of the cover in
the Dewar vessel.
5. Drop the shot with the temperature of 100 0C into the mesh for samples, close the cover, and
thoroughly mix the water with the shot.
6. Read the mixture temperature when the temperature of the water stops rising.
7. Determine the additional mass m of the shot.
8. Repeat the experiment with copper and glass shot.
13
EXPERIMENT 2: Measurement of Specific Heat of Solids
Name:__________________________________ ID: _______________________
Instructor: ________________________________________________________
Section:____________________________Date:___________________________
Lab Partners:______________________________________________________
DATA SHEET
Table 1: Measured values for determining the specific heat capacities
Substance m (g) M Equilibrium Temperature (M)
Steel
Brass
Evaluation
Mass of calorimeter mcal = ..........................
Specific heat of Aluminum cAl = 0.215 cal/g. K
Mass of Water mw = ....................................
Specific heat of Water cw = 1 cal/g. K
14
Specific heat of Solid is given by
..................................................................................................................................................................
..................................................................................................................................................................
..................................................................................................................................................................
..................................................................................................................................................................
..................................................................................................................................................................
..................................................................................................................................................................
..................................................................................................................................................................
..................................................................................................................................................................
Table 2: Specific heat capacities determined experimentally and the corresponding values quoted in the
literature
Substance c (cal/K.g) c (cal/K.g) % error
Experimental Literature
Steel 0.12
Brass 0.092
( ))(m
)cmcm(c
M
MwAlcalww
−
−+=
1
15
Experiment 3:
Determination of the Velocity of Sound by Using Columns
Air
Aim:
The aim of this experiment is to determine the velocity of sound by using columns
air.
Apparatus
Resonance tube apparatus as in the figure 9.1 - Set of tuning forks - Rubber mallet
16
Figure 9.1: A Resonant tube apparatus. The length L of the tube is varied by raising and
lowering the reservoir can to adjust the water level
Theory
A wave is a broad distribution of energy, filling space through which it passes. There are three main
types of waves. Mechanical waves are the most familiar these are the waves that are produce in a
medium such as water (ocean waves), air (sound waves), or solid (seismic waves). Electromagnetic
waves require no material medium to propagate (move). Examples are visible light, radio, and
microwaves. All electromagnetic waves travel through a vacuum at the same speed, 𝑐 = 299792458 𝑚 .
Matter waves are waves that produced by particles such as electrons, protons, and other fundamental
particles. Atoms and molecules may even be considered matter waves. Waves propagate in two ways,
transversely, longitudinally or both. In transverse waves, the element of the wave moves perpendicular to
the motion while for longitudinal waves the element moves parallel to the motion. Both types of waves
are traveling waves. The wavelength λ, of a wave may be described as the distance (parallel to the
direction of the wave’s travel) between repetitions of the shape of the wave (or wave shape). The
principle of superposition states that when several effects occur simultaneously, their net effect is the
sum of the individual effects. Overlapping waves algebraically add to produce a resultant wave (or net
wave). Overlapping waves do not in any way alter the travel of each other. The combining of waves is
called interference and waves are said to interfere. If two waves of the same amplitude and wavelength
travel in opposite directions along a stretched string, their interference with each other produces a
standing wave. The resultant wave produces an interference pattern where at the minimum amplitude a
node is formed and at the maximum an antinode.
Figure 9.2: Representation of Node and antinode
17
The period 𝑇,of a wave is described as the time it takes any element to move through one full
oscillation. Angular frequency of the wave is define 𝜔=2𝜋/𝑇 and the SI unit is radians per
second. The frequency f, is the number of oscillations per unit time and is related to the period
by 𝑓=1/𝑇=𝜔/2𝜋. We may then write the velocity as 𝑣=𝜆/𝑇=𝜆𝑓. A wave that is reflected off of a
barrier and travels in the opposite direction of the incidence wave may produce at large
frequencies a standing wave pattern or oscillation mode. The standing wave that is produced at a
resonance and the frequencies at which the wave resonates are known as resonate frequencies.
\Resonant frequencies that correspond to these wavelengths by the formula
L
nvvf
2==
with n=1,2,3,… The oscillation with the lowest frequency corresponds to the fundamental mode
(n=1) or first harmonic, the second harmonic to mode 2 and so on.
Sound waves are longitudinal waves that involve oscillations that are parallel to the direction of
the wave. In this experiment, sound waves (compressional waves) will be generated by a
vibrating tuning fork. The medium is air at room temperature enclosed in a glass tube, sealed at
the lower end by a column of water (see figure). When the tuning fork is set into vibration, a
train of waves consisting of alternating compressions and rarefactions of the air is sent down the
tube. This wave train is reflected at the water surface with a phase change of 180o and passes
back up the tube. At the open end of the tube, it is again reflected, but with no phase change in
this case. The resultant waves in the tube are a combination of incident and reflected wave trains
and may be very complex, just as in the case of transverse waves in a string. But just as in the
case of the string, it is possible to produce standing waves when the proper relationship between
frequency, wave speed and length of air column is achieved. The air column will then vibrate
strongly in segments, with a frequency equal to the frequency of the tuning fork. This
phenomenon occurs when the length of the air column is such that an odd multiple of quarter-
waves “fits” the air column, since there must be a node at the lower end of the air column (at the
surface of the water) and a loop or anti-node near the open end of the tube. Under these
conditions, the air column resonates with the tuning fork and the intensity of sound from the
system is considerably increased. You will listen for the increased sound as evidence that the air
column is supporting a standing sound wave.
In a pipe with only one open end, standing waves may be produced at the resonant frequencies.
18
Figure 9.3: The longitudinal vibrations of air in a pipe, closed at the left and open at the
right
Across the open end there is an antinode and on the closed end a node is produced. A full
wavelength must be 𝜆=4𝐿. As a result the closed in pipe resonant frequencies correspond to
n
L4= for n =1,3,5…
Thus,
L
nvvf
4==
for n =1,3,5…
Figure 9.4: The longitudinal vibrations of an air column, in a pipe with water at the
bottom.
Procedure:
Strike a tuning fork of frequency 512 Hz with a rubber mallet and hold it at about an inch above
the open end of the resonance tube with its prongs horizontal. Adjust the water level starting
from its highest level.
2. Gradually increase the length of the air column by lowering the can to find the first position
of resonance, where the sound coming out of the air column is loudest. You may have to strike
19
the fork several times and move the water column up and down to precisely locate the resonance
position.
3. Continue this procedure to find second (and if possible, the third) position of resonance.
Record these lengths as 𝑙1 and 𝑙2.
4. Repeat the experiment with a tuning fork of different frequency.
20
EXPERIMENT 3
Determination of the Velocity of Sound by Using Columns
Air
Name:__________________________________ ID: _______________________
Instructor: ________________________________________________________
Section:____________________________Date:___________________________
Lab Partners:______________________________________________________
DATA SHEET
Observations:
Table 1:
Trial Frequency f (Hz) 1/f (Hz-1) Length L (m)
1
2
3
4
5
6
Calculations:
1. Calculate the speed of sound from the formula
𝑣=𝜆𝑓=2(𝑙2−𝑙1)
.......................................................................................................................................................
21
2. If you get only the first resonance, and not the second resonance then, to calculate the speed of the
sound, use
𝑣=4𝑓𝑙1.
.......................................................................................................................................................
3. Compare the calculated speed of sound with the theoretical value from the formula
𝑣=331.16+0.61𝑇 (℃)
.......................................................................................................................................................
4. Plot a graph for L (m) (as y axis) verses 1 /f (Hz) (as x-axis) and find the slope
Slope = .......................................................
5. From the slope determine the velocity of sound as
v = 4 (slope)
Speed of sound in air v = ..................................................
6. Calculate the % error in your experiment. Use theoretical value for the speed of sound in pure air at 20
oC is about 343m/s.
% error = ---------------------------------------
Don’t Forget Units
22
Experiment 4: Measuring The Buoyancy Force
Objects of the experiments • Measuring the force F acting on a cylinder immersed in a liquid and determining the
buoyancy force.
• Confirming the proportionality between the buoyancy force FG and the immersion depth
h.
• Determining the densities ρ of three different liquids.
Apparatus 1 Archimedes cylinder 1 precision dynamometer 1 steel tape measure 1 beaker, 250 ml, ts, hard glass glycerine, 99 %, 250 ml ethanol, denaturated, 1l in addition:distilled water, 250 ml
Principles
According to Archimedes’ principle, a body immersed in a liquid is acted upon by a buoyancy
force FG, the magnitude of which is equal to the weight of the displaced liquid
Fig. 1 Diagram for calculating the buoyancy force FG on a body immersed in a liquid
23
Setup and execution of the experiment
Fig. 2 Experimental setup for measuring the buoyancy force as a
function of the immersion depth
Experimental Procedure The experimental setup is illustrated in Fig. 2.
1) Determine the dimensions of the solid cylinder.
2) Hold the dynamometer suspended vertically and adjust the zero position.
3) Suspend the solid cylinder from the dynamometer and determine its weight F0.
4) To make determination of the immersion depth easier,make equidistant marks on the
solid cylinder with a waterand ethanol proof pen.
5) Fill about 200 ml of distilled water into the beaker.
6) Immerse the solid cylinder up to the first mark and measurethe force F.
7) Immerse the solid cylinder further and measure the force Fas a function of the immersion
depth h.
8) Pour out the distilled water and dry the beaker and the solidcylinder using, for example,
absorbent tissue.
9) Repeat the experiment with ethanol and then with glycerine.
24
Experiment 4: Measuring The Buoyancy Force
Name:_________________________________ID: _______________________
Instructor: ________________________________________________________
Section:___________________________Date:___________________________
Lab.Partners: ____________________________________________________
DATA AND ANALYSIS
Data of the solid cylinder:
Diameterd = …… mm, height H = ……… mm weight F2= …………… N
Table 1: The force F acting on the solid cylinder as a function of the immersion depth h
h/mm F/N
Water Ethanol Glycerin
25
Evaluation and results Plot the buoyancy force FG calculated from the data of Table 1 is plotted as a function of the
immersion depth h. The slopes (cf. Eq. (II))
a = ρ × g × A
of the straight lines drawn through the origin and the corresponding densities ρ of the liquids are
compiled in Table 2. The deviation from the values quoted in the literature, which arealso given
in Table 2, is due to an admixture of air during the process of filling the liquids into the beaker.
Tab. 2: The slopes of the straight lines and the densities ρ of the liquids calculated from
them
Liquid 1-a N.mm ρ (g/cm3) ρ (g/cm3)
Litrature
Ethanol
Water
Glycerin
26
Experiment 5: Determination of the viscosity of
viscous fluids
Objects of the experiments
Assembling a falling-ball viscosimeter.
Determining the viscosity of glycerine.
Apparatus
1 steel ball, 16 mm dia
1 guinea-and-feather apparatus
6 glycerine, 99 %, 250 ml
1 counter P
1 holding magnet with clamp
1 low-voltage power supply, 3, 6 ,9 ,12 V
1 morse key
1 stand base, V-shape
1 stand rod, 100 cm
1 stand rod, 25 cm
1 Leybold multiclamp
1 steel tape measure, 2m
1 pair of magnets, cylindrical
connection leads
additionally recommended:
1 precision vernier callipers
1 measuring cylinder, 100 ml, plastic
1 electronic balance LS 200, 200g: 0,1 g .
Principle
27
28
Experimental Procedure
1. Set the counter P to zero by pressing the key “0”.
2. Trigger off the morse key, and observe the falling ball.
3. As soon as the ball has reached the mark (c), release the morse key.
4. Read the time of fall t from the counter P and record it.
5. If the ball does not fall at all or if it falls with a delay:
• Check the connections.
• Turn the iron core a bit upward.
• Choose a lower voltage for the holding magnet.
6. If the ball falls without the morse key‘s being triggered:
– Turn the iron core a bit downward.
7. Repeating the measurement:
o Turn the voltage for the holding magnet to 12 V and turn the knurled
screw (a) to stop.
o Get grip of the steel ball from outside on the bottom of the vessel
with the pair of magnets sticking together (red mark outward), and
move the ball slowly upward along the wall of the vessel until it
reaches the holding magnet. Using a bent piece of wire, for example,
push the ball exactly below the iron core (see Fig. 2).
o Turn the knurled screw upward again, set the counter P to zero, and
repeat the measurement of the time of fall.
8. If the devices recommended in addition are available (seeabove):
▪ Determine the inner diameter D of the guinea-and-feather
apparatus, and the diameter d and the mass m2 of the steel ball.
▪ Put the measuring cylinder on the electronic balance, and
counterbalance.
▪ Fill 100 ml of glycerine from the storage bottle into the
measuring cylinder, and determine its mass.
29
30
Experiment 5: Determination of the viscosity of
viscous fluids Name:_________________________________ID:
_______________________
Instructor: ________________________________________________________
Section:___________________________Date:___________________________
Lab.Partners: ____________________________________________________
DATA AND ANALYSIS
TABLE 1: Times of fall t
n t/ms
Distance of fall: s = …………………. cm
Diameter of the ball: d = ……………….. mm
Diameter of the guinea-and-feather apparatus: D = ………. mm
Mass of the ball: m2 = …………….. g
Mass of 100 ml of glycerine: m1= ……………….G
31
Evaluation and results
………………………………………………………………………………………
………………………………………………………………………………………
………………………………………………………………………………………
………………………………………………………………………………………
………………………………………………………………………………………
………………………………………………………………………………………
………………………………………………………………………………………
………………………………………………………………………………………
………………………………………………………………………………………
32
Experiment 6: Measuring the surface tension
Objects of the experiments
• Creating a liquid layer between the edge of a metal ring and the surface of the liquid.
• Measuring the tensile force acting on the metal ring just before the liquid layer breaks
away.
• Determining the surface tension from the measured tensile force.
Apparatus
➢ 1 apparatus for measuring surface tension
➢ 1 precision dynamometer 0.1 N
➢ 1 vernier callipers
➢ 1 crystallization dish, 95 mm dia., 55 mm high
➢ 1 laboratory stand II
➢ 1 stand base, V-shape, 20 cm
➢ 1 stand rod, 75 cm, 1 clamp with hook
➢ distilled water, ethanol
Principles The surface tension is due to the fact that a molecule on thesurface of a liquid is acted upon by
attractive forces fromadjacent molecules towards one side only (see Fig. 1). Theresultant force
acting on the molecule points into the liquid andis perpendicular to the surface.
33
In order to enlarge the surface, i.e. to take more molecules tothe surface, energy has to be
supplied. The ratio of the energy ΔE supplied at a constant temperature and the change of the
surface ΔA is called surface energy or surface tension of theliquid:
A
E
= (i)
The surface tension can be measured, e.g., by means of ametal ring with a sharp edge which at
first is immersed in theliquid so that it is completely wetted. If the ring is slowly takenout of the
liquid, a thin liquid layer is pulled up (see Fig. 2). Theoutside and inside surface of the liquid
layer changes by
xRA •••= 4 (ii)
R : Radius of the metal ring
34
when the metal ring is lifted by Δx. Pulling up the ring requires the force
x
EF
= (iii)
to be applied. If this force is exceeded, the liquid layer breaks away. Because of Eqs. (I)-(III),
the surface tension is
R
F
••=
4 (iv)
Setup
• The experimental setup is illustrated in Fig. 3.
• Carefully clean the crystallization dish.
• Carefully remove fat from the metal ring, e.g. with ethanol, and suspend it from the
dynamometer.
• Suspend the dynamometer from the clamp with hook so that the ring hangs over the
crystallization dish.
• Set the laboratory stand to a height of approx. 10 cm.
35
Carrying out the experiment
1. Determine the diameter of the metal ring.
2. Make the zero adjustment at the dynamometer using the movable tube.
3. Fill distilled water into the crystallization dish.
4. Lower the clamp with hook until the metal ring is completely immersed.
5. Cautiously lower the laboratory stand, always observing the tensile force at the
dynamometer.
6. As soon as the edge of the metal ring emerges from the liquid, the liquid layer is formed.
When the tensile force
7. does no longer increase although the laboratory stand is further lowered, the layer is just
before breaking away.
8. Read the tensile force just before the layer breaks away, and take it down.
9. Pour the distilled water out, and dry the crystallization dish and the metal ring.
10. Repeat the measurement with ethanol.
36
Experiment 6: Measuring the surface tension Name:_________________________________ID: _______________________
Instructor: ________________________________________________________
Section:___________________________Date:___________________________
Lab.Partners: ____________________________________________________
DATA AND ANALYSIS
Diameter of the metal ring: 2 R =…………
Measurement with water: F = …………
Measurement with ethanol: F = …………
Evaluation
Measuring result for water: σ = ………………mN m–1
Literature value for water at 25 ºC: σ = 72 mN m–1
Measuring result for ethanol: σ = mN m–1
Literature value for ethanol: σ = 22 mN m–1
Result
--------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------
37
--------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------
38
Experiment 7: Temperature measurement with a thermocouple
39
40
41
42
Experiment 8: Determining of the focal length of a concave mirror and
convex mirror.
43
44
45
46
Experiment 9: Determining of the focal length of the converging and diverging lenses
47
48
49
50
Experiment 10: Standing waves (Melde’s Experiment)
51
52
53
Experiment 11: Refraction of Light (Snell’s Law)
54
55
56
