Temperature and Thermometers
Temperature and Thermometers
Temperature and Thermometers
the measure of
the hotness or the coldness
of a body
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Temperature is measured in ...
SI unit Practical
unit
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Symbols Kelvin Celsius
T t or q
T/K
t / °C
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Relationship … Kelvin and Celsius
t / °C = T / K 273.15
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Thermometers measure temperature.
Thermometric Property
• A physical property
• that changes measurably
• with temperature
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Thermometric Property Examples
• Length of a liquid column
• e.m.f. of a thermocouple
• pressure of a gas at constant volume
• volume of a gas at constant pressure
• resistance
• colour
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Thermometric Property Examples
• Length of a liquid column
Mercuryinglass thermometer
Alcoholinglass thermometer
7 8 ° C
+
15 ° C
3 5 7 °C 1
+
Laboratory thermometer
° C
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Clinical thermometer L
(Barometer) / Thermometer
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Thermometric Property Examples
• e.m.f. of a thermocouple
Infrared
Car engine temperature
(but …)
200 °C to 1700 °C
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Thermometric Properties
Volume of a gas at constant pressure
Volume increases
measurably
with temperature
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Thermometric Property Examples
• Pressure of a gas at constant volume
Pressure increases
measurably
with temperature
V o l u m e
o n s t a nt
C o m e t e r
T h er m
Gas
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Thermometric Property Examples
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Using A Thermometric Property
To Measure Temperature
In pure In steam
melting above
ice boiling water
Mark ...
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Using A Thermometric Property Warm water temp. = ??
To Measure Temperature
Measure L …
Calculate q from graph
Length
L
LSTEAM
LICE
0°C q 100°C
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Using A Thermometric Property Warm water temp. = ??
To Measure Temperature
Measure R …
Calculate q from graph
Resistance
RICE RSTEAM
0°C q 100°C
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Temperature of the warm water =
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A standard thermometer is needed.
In school lab.
… a mercuryinglass thermometer
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“Fever Strip ..”
Clinical Thermometer
Liquid Crystals
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InfraRed Radiation
Thermometer
Provides accurate and rapid
temperature readings from the ear
within three seconds.
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Thermocouple
DataStudio
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Bimetallic Thermometers
Oven Refrigerator
Lab.
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Boiler Thermometer
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Car Temperature Gauge
Thermistor (or Thermocouple)
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To Plot The Calibration Curve Of A Thermometer Using
The Laboratory Mercury Thermometer As A Standard
APPARATUS
Alcohol thermometer (on metre stick)
Mercury Thermometer
Beaker & water, etc.
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To Plot The Calibration Curve Of A Thermometer Using
The Laboratory Mercury Thermometer As A Standard
PROCEDURE
1. Heat gently
… take readings every 10°
2. Measure (2)
… Length of .. & Temperature
3. L=?
Temperature from mercury thermometer
4. Repeat, every 10°, to graph.
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To Plot The Calibration Curve Of A Thermometer Using
The Laboratory Mercury Thermometer As A Standard
RESULTS
Length
Temperature
PRECAUTIONS
1. Heat gently … thermal equilibrium
2. Etc.
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Calibration Curve Measuring Temperature With It
Length
L
L
Temperature
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Absolute Zero 273.15 °C
Freezer 18 °C
Fridge / Icebox 4 °C
Water Freezes 0 °C
Fridge Main + 4 °C
Room Temp. + 20 °C
Body Temp. + 37.0 °C
Water Boils +100 °C
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Alcohol freezes 115 °C
Alcohol boils + 78 °C
Mercury freezes 39 °C
Mercury boils + 357 °C
Chips + 200 °C
Horse + 38.3 °C
Bunsen flame + 1500 °C
Filament + 2500 °C
Sun’s surface + 6000 °C
Hbomb / Abomb Millions
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