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PRACTICAL THERMOMETERSTOPIC 10 : TEMPERATURE For GCE O-Levels Physics 5054

Transcript of 10 Practical Thermometers

Sunday, February 20, 2011

PRACTICAL THERMOMETERSTOPIC 10 : TEMPERATURE

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Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

Sunday, February 20, 2011

SO MANY TYPES OF THERMOMETERS !

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Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

WHAT ARE THE COMMON SIMILARITIES BETWEEN THEM?

Sunday, February 20, 2011

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com3

Good thermometers have the following features: Safe to Use Easy to read scale Able to measure a wide range of temperature Sensitive to small temperature changes

Responsive to temperature changes

Sunday, February 20, 2011

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com4

FEATURES OF A THERMOMETER

WHAT CHARACTERISTICS CAN BE USED TO DESCRIBE THERMOMETERS ?

Sunday, February 20, 2011

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com5

SENSITIVITYCOMMONCHARACTERISTICS

RANGE LINEARITY

Sunday, February 20, 2011

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com6

CHARACTERISTICS OF THERMOMETER

RANGEDefinition The lowest reading to the highest reading that can be measured.

Sunday, February 20, 2011

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com7

RANGEPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com8

What is the range of this thermometers?

Sunday, February 20, 2011

RANGEPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com9

What is the range of this thermometers?

Thermometer ASunday, February 20, 2011

Thermometer B

SENSITIVITYDefinition How large the change in reading is when there is a small change in temperature.

Sunday, February 20, 2011

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com10

LINEARITYDefinition Uniform increase/decrease of the thermometric properties used with equal increase/decrease in temperature

Sunday, February 20, 2011

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com11

LIQUID-IN-GLASS THERMOMETERSLENGTHPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com12

Physical property used to measure temperature:

Laboratory ThermometerSunday, February 20, 2011

Clinical Thermometer

LABORATORY THERMOMETERFunction To measure temperatures or changes in temperatures with high degrees of accuracy.sed in ally u Norm ories. aborat lPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com13

Laboratory ThermometerSunday, February 20, 2011

LABORATORY THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com14

Its Structure & Function

Thin wall glass bulb

Function Allow conduction of heat quickly through the glass

Sunday, February 20, 2011

LABORATORY THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com15

Its Structure & Function

Small bulb

Function Store small amount of liquid. Small amount of liquid is more responsive to heat

Sunday, February 20, 2011

LABORATORY THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com16

Its Structure & Function

Fine & Uniform Capillary bore Function Allows noticeable movement of liquid column for small change in temperature Function Allows even expansion of the liquid.

Sunday, February 20, 2011

LABORATORY THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com17

Its Structure & Function

Thick long tube walls Function Acts as a magnifying glass for easy reading of scales.

Sunday, February 20, 2011

LABORATORY THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com18

Its Structure & Function

Small-sized thermometer Function Portable and cheap to produce.

Sunday, February 20, 2011

CLINICAL THERMOMETERSFunction To measure body temperature.Clinical Thermometerhome sed at ally u inics. orm N ls / cl ospita or in hSunday, February 20, 2011

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CLINICAL THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com20

Its Structure & Function

Thin wall glass bulb

Function Allow rapid conduction of heat through the glass

Sunday, February 20, 2011

CLINICAL THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com21

Its Structure & Function

Very fine capillary bore Function Allows for greater measurement sensitivity

Sunday, February 20, 2011

CLINICAL THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com22

Its Structure & Function

Limited short scale range Function Allows for greater measurement accuracy

Sunday, February 20, 2011

CLINICAL THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com23

Its Structure & Function

Narrow constriction above the bulb Function Prevents the liquid from entering the bulb too quickly. Function Provides a more steady temperature reading

Sunday, February 20, 2011

CLINICAL THERMOMETERPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com24

Its Structure & Function

Pear-shaped cross-section of the stem. Function Acts as a magnifying glass in one direction for easy reading of temperature scales.Sunday, February 20, 2011

LABORATORY VS CLINICALLIST OUT THREE DIFFERENCES BETWEEN THEMPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com25

Thermometers

Sunday, February 20, 2011

IMPROVING THERMOMETER DESIGNMore Responsive to temperature changesPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com26

for Liquid-in-glass thermometers

Decrease the thickness of the bulbs wall.

Thinner glass bulb will allow faster and better conduction of heat to the mercury / alcoholSunday, February 20, 2011

IMPROVING THERMOMETER DESIGNMore Sensitive to small temperature changesPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com27

for Liquid-in-glass thermometers

Decrease the size of the bore.

Smaller bore size will be able to produce larger liquid column change for very small change in temperature.Sunday, February 20, 2011

IMPROVING THERMOMETER DESIGNMeasure larger range of temperature.Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com28

for Liquid-in-glass thermometers

Increase the length of the bore and thermometer.

Longer bore will allow further expansion of the mercury / alcohol column with temperature.Sunday, February 20, 2011

THERMOCOUPLEVOLTAGE / EMFPrepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com29

Physical property used to measure temperature:

Thermocouple ThermometersSunday, February 20, 2011

THERMOCOUPLEFunction To measure wide range of temperatures, rapidly changing temperatures and temperatures of small objects.sed in ally u Norm tries. indusSunday, February 20, 2011

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Sunday, February 20, 2011

A simple thermocouple thermometer

Hot Junction Cold Junction31

THERMOCOUPLEIts Structure

Voltmeter Two types of wires

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

Voltmeter reading

This value gives us the Calibration Temperature

STEAM POINT 100 degrees CelsiusSunday, February 20, 2011

Hot Junction

Cold Junction

ICE POINT 0 degrees Celsius

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com32

Calibrating the temperature scale on a thermocouple

THERMOCOUPLE

Voltmeter reading

This value gives us the Temperature Difference

Put in Unknown TemperatureSunday, February 20, 2011

Hot Junction

Cold Junction

Keep at ICE POINT

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com33

Using a simple thermocouple

THERMOCOUPLE

Use with the Centrigrade Equation to determine the temperature

Unknown temperature in

V = 0 C V

Unknown temp

-V V -

Ice point

X 100

Steam point

Ice point

Thermocouple thermometer measures the temperature difference between the two junctions.Sunday, February 20, 2011

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com34

THERMOCOUPLE READINGS

Voltmeter reading

This value gives us the Calibration Temperature

V -VSteam point

Ice point

STEAM POINTSunday, February 20, 2011

Hot Junction

Cold Junction

ICE POINT35

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

To determine the temperature in Centrigrade / Celsius:

THERMOCOUPLE

Voltmeter reading

This value gives us the Temperature Difference

V

Unknown temp

-V

Ice point

Unknown TemperatureSunday, February 20, 2011

Hot Junction

Cold Junction

ICE POINT36

Prepared by Cg Edna Maria Hj Osman. E-mail: edna.maria.osman@gmail.com

To determine the temperature in Centrigrade / Celsius:

THERMOCOUPLE

Us