3. Objectives
• After learning: You are excepted to be
able to explain the definition of
temperature
• Measure the temperature of substance by
using thermometers
• Distinguish various thermometers
4. Particles are always moving.
When you heat water, the water molecules move
faster.
When molecules move faster, the substance gets
hotter.
When a substance gets hotter, its temperature
goes up.
5. Learning Check
Suppose you place water in a freezer.
A. The water particles move
1) faster 2) slower 3) the
same
B. The water will get
1) hotter 2) colder 3)
stay the same
C. The temperature of the water will
6. Solution
Suppose you place water in a freezer.
A. The water particles move
2) slower
B. The water will get
2) colder
C. The temperature of the water will be
2) lower
7. Thermometer
Measures the hotness or coldness of an
object
Determined by using a thermometer that
contains a liquid that expands with heat
and contracts with cooling.
8. A CTIVITY 2.1. M EASURING T EMPERATURE
Procedures
A B C
Cold water Tap water Warm water
9. Thermometer Scale
Put glass on the flat surface
Hold on the tip of thermometer (do not hold
bulb of thermometer)
bulb
Your eyes must be perpendicular with the
scale
9
10. Thermometer
• Touching sense is unreliable for measuring
exact temperature of an object
• To measuring exact temperature of an
object, we can use Thermometer
• The principle used in a thermometer is the
volume change of liquid or EXPANSION
principle.
• For almost all substance will:
– expand (volume is increased) when
they are heated
– contract (volume is decreased)when
they are cooled
10
11. Thermometer Scale
1. What are liquids commonly used to filled
thermometer?
2. Find the advantages and weakness of alcohol as
thermometric liquid.
3. Find the advantages and weakness of mercury as
thermometric liquid.
4. Can water used as thermometric liquid? Give
reasons for your answer.
5. Make a diagram comparison of Upper fixed point
and lower fixed point of
Celcius, Reamur, Fahrenheit and Kelvin scale.
6. What is absolute zero?
11
12. Thermometer
1. Column of vacuum space
2. Measured temperature
3. Capillary tube
4. Thermometer scale
Bulb filled with mercury Or
alcohol
12
13. Thermometer Scale
Absolute zero is the lowest possible
temperature where nothing could be colder, and
no heat energy remains in a substance.
Absolute zero is the point at which molecules
do not move
It is a theoretical limit and cannot be achieved
with the current technology available.
Absolute Zero = 0 K
0 K = - 459.67 F = - 273.15 C
13
14. Thermometer
Determine the Boiling point of pure
upper fixed point water at 1 atm
(Ta)
Divided
between Ta
and Tb
Every part =
temperature per unit
Determine the lower Melting point of
fixed point (Tb) ice at 1 atm
14
15. Thermometer Scale
CELCIUS REAMUR FAHRENHEIT KELVIN
Upper 100 C 80 R 212 F 373 K
point
Lower 0 R 32 F 273 K
0 C
point
0 F
O K = -273 C
C : R : F : K Absolut
COMPARISON
100 : 80 : 180 : 100
SCALE e zero
5 : 4 : 9 : 5
15
16. Learning Check
A. Temperature of freezing water
1) 0 F 2) 0 C 3) 0 K
B. Temperature of boiling water
1) 100 F 2) 32 F 3) 373K
C. Number of Celsius units between the
boiling and freezing points of water
1) 100 2) 180 3) 273
17. Solution
A. Temperature of freezing water
2) 0 C
B. Temperature of boiling water
3) 373K
C. Number of Celsius units between the
boiling and freezing points of water
1) 100
18. Conversion Unit
Tx = temperature of thermometer X
Xb = Lower point of thermometer X
Xa = Upper point of thermometer X
Ty= temperature of thermometer Y
Yb = Lower point of thermometer Y
Ya = Upper point of thermometer Y
18
19. E XAMPLE
1. What does 45 C equal if it is measured in a Fahrenheit
thermometer?
Given: TC = 45 C
Question: TF = ?
TF Fb TC Cb
Solution:
Fa Fb Ca Cb
TF 32 45 0
212 32 100 0
TF 32 45
180 100
45
TF 32 180
100 9
9
45
TF ( 180) 32 81 32 113 F
5
19 100
20. 2. Arman made his own thermometer called thermometer X
and given scale like in the figure below. If thermometer X
shows 25, what is the temperature according to celcius
scale?
Celci
Tc Cb Tx Xa X us 100 C
40 X
Ca Cb Xa Xb
Tc 0 25 ( 10 )
100 0 40 ( 10 )
E XAMPLE 25 X Tc =?
Tc 25 10
100 40 10
-10 X
0 C
Tc 35
100 50
35 2 70 C
Tc 100 35 2
20 50
22. Learning Check
Do Conversion unit of temperature
below.
1. 40 R = …………… C
2. 10 C = ……………. F
3. -40 C = ……………. F
4. 27 C = ……………… K
5. 283K = ……..………. F
6. Thermometer A and B are
used to measure
temperature of an object. 320 B
What is Y when
thermometer A shows 100
A? 50 A 20 B
25. Liquid thermometer
glass tube filled with liquid (often mercury or alcohol)
that expands/contracts
Alcohol and mercury have their own advantages and
weakness.
Advantages Weakness
It has a regular thermal expansion It wets the tube wall
It has a large coefficient of thermal It has a low boiling point (80 C) It is
expansion unsuitable to measuring high
temperature
It has low freezing point (-115 C), it is It has a high specific heat capacity, so
suitable for measuring low
www.tyas- it needs a high energy to raise
physics.blogspot.com
temperature temperature
25
26. Liquid thermometer
Advantages Weakness
It is easy to see, have a shining It is very expensive
color
It is not wets tube wall It is a poisonous substance
It adapts the ambient temperature Unsuitable for measuring a very low
easily temperature because it has high
freezing point
It has regular thermal expansion
It has a high boiling point
(357C), suitable to measure high
temperature
It has width scale range (-39 C -
357 C)
26
27. Kinds of thermometer
A gas thermometer measures
temperature by the variation in
volume or pressure of a gas
It has width range (2500C -
15000C)
This thermometer makes use of a
bimetallic strip that consists of
two strips of different metal
joined together.
As temperature increases, the
coiled bimetallic strip bends
more to rotate a pointer around
on a scale.
27
28. Kinds of thermometer
Wires made of two different metals are joined
together to form two junctions.
It is very sensitive and can measure a wide range of
temperatures.
It is commonly used in industry to measure the
temperatures of ovens and furnaces
28
29. Kinds of thermometer
Thermometer that measures
temperature by changes in the
resistance of a spiral of platinum
wire
An instrument for measuring
high temperatures (over
60000C)
It used to measure thermal
radiation
29
30. • Clinical Thermometer
• Wall Thermometer
• Maximum and Minimum Six-Bellani
Thermometer
• Laboratory Thermometer
30
31. Kinds of thermometer
Used to accurately determine the
temperature of the human body;
the most common type is a
mercury-in-glass thermometer
It has scale range (35 C- 42 C)
Used to measure the air
temperature of a room
31
32. Kinds of thermometer
Also called by Six-Bellani
Thermometer
Can measure the maximum and
minimum temperature during a
given time.
It is common in use wherever a
simple way is needed to measure
the extremes of temperature at
a location, for instance in
meteorology and horticulture.
Used for laboratory purpose
32
