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the measure of

the hotness or the coldness

of a body

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Temperature is measured in ...

Kelvin and Celsius

SI unit Practical

unit

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Symbols Kelvin Celsius 

T t or

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 

•  e.m.f. of a thermocouple 

•  pressure of a gas at constant volume 

•  volume of a gas at constant pressure 

•  resistance 

•  Length of a liquid column 

•  colour

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Thermometric Property - Examples 

•  Length of a liquid column 

 L 

Mercury-in-glass thermometer

Alcohol-in-glass thermometer

Laboratory thermometer

Clinical thermometer

(Barometer) / Thermometer

 +  3 5 7  ° C 

 +  7 8  ° C 

 - 3 9  ° C 

 - 1 1 5  ° C

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Thermometric Property - Examples 

•  e.m.f. of a thermocouple

Infra-red

Car engine temperature(but …)

- 200 °C to 1700 °C

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Thermometric Properties

Volume increases

measurably

with temperature

Volume of a gas at constant pressure

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Pressure increases

measurably

with temperature 

•  Pressure of a gas at constant volume

 C o n s t a n t  V

 o l u me 

 G a s  T h

e r m o me te r 

Thermometric Property - Examples

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Thermometric Property - Examples 

•  Resistance Metal (Platinum)

Thermistor (Semiconductor)

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Using A Thermometric Property

To Measure Temperature

In pure

melting

ice

In steam

above

boiling water

Mark ...

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Using A Thermometric Property

To Measure Temperature 

 L ICE

 L STEAM  

0°C 100°C

Length 

 L

Warm water temp. = ??

Measure  L …

Calculate 

from graph

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Using A Thermometric Property

To Measure Temperature

0°C 100°C

Resistance 

 R

Warm water temp. = ??

Measure  R …

Calculate 

from graph 

 R ICE

 R STEAM 

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55.3 ° … using the Mercury thermometer

55.7 °C … using the Resistance thermometer

Temperature of the warm water =

The different thermometric propertiesvary differently with temperature.

All agree at … 0 °C and 100 °C

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A standard thermometer is needed.

In school lab.

… a mercury-in-glass thermometer

Calibrate other thermometers using this.

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Clinical Thermometer

“Fever Strip ..”

Liquid Crystals

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Provides accurate and rapid

temperature readings from the ear

within three seconds.

Measures the temperature of the

infrared heat given by the eardrum

and surrounding tissues 

Infra-Red Radiation

Thermometer

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Thermocouple

- DataStudio

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Bimetallic Thermometers

Oven Refrigerator

Lab.

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Boiler Thermometer 

•  Thin copper pipe 

•  “Santotherm” expands 

•  Pressure on diaphragm 

•  Turns needle

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Car - Temperature Gauge

Thermistor (or Thermocouple)

Platinum Resistance Thermometer

Thermocouples

Constant Volume Gas Thermometer (Standard)

Optical Pyrometers

To Plot The Calibration Curve Of A Thermometer Using

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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 ThermometerBeaker & water, etc.

To Plot The Calibration Curve Of A Thermometer Using

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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.

To Plot The Calibration Curve Of A Thermometer Using

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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 equilibrium2. Etc.

Calibration Curve - Measuring Temperature With It

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Calibration Curve Measuring Temperature With It

Length

Temperature 

 L

 L

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Absolute Zero - 273.15 °CFreezer

Fridge / Ice-box - 4 °C

Water Freezes

Fridge - Main+ 20 °CRoom Temp.

Body Temp.

- 18 °C

0 °C

+ 4 °C

+ 37.0 °C

Water Boils +100 °C

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Alcohol freezesAlcohol boils + 78 °C

Mercury freezes - 39 °C

Mercury boils + 357 °C

Chips

Horse

Bunsen flame + 1500 °C

Filament + 2500 °C

- 115 °C

+ 200 °C

+ 38.3 °C

Sun’s surface + 6000 °C

H-bomb / A-bomb Millions