TemperatureBy Mr. Joe

Subject

Objectives

Quiz

Learning’s

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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

Temperature

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.

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 be

1) higher 2) lower 3) the same

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

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.

ACTIVITY 2.1. MEASURING TEMPERATUREProcedures Fill in glass A with cold water, B with tap water

and C with warm water . Put your left forefinger into A and your right forefinger to C. How do you feel?

Simultaneously put your forefinger to B. Do you feel glass B is hot or cool ? Which forefingers can you rely on to measure temperature?

Now change your forefinger with thermometer, measure of water in glass A, B and C. Write down result in the form of a table Write down result in the form of a table

Discuss! Compare the results of step 4 with the result of step

2 – 3 What is your conclusion?

ACold water

BTap water

CWarm water

9 TEMPERATURE

Thermometer Scale

Reading thermometer

Put glass on the flat surfaceHold on the tip of thermometer (do not hold bulb of thermometer)

Your eyes must be perpendicular with the scale

bulb

Thermometer

10 TEMPERATURE

• 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

11 TEMPERATURE

Thermometer Scale

Exercise1. 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?

12 TEMPERATURE

Thermometer

Part of Thermometer

1. Column of vacuum space

2. Measured temperature3. Capillary tube

4. Thermometer scale

Bulb filled with mercury Or alcohol

13 TEMPERATURE

Thermometer Scale

ABSOLUTE ZERO

Absolute Zero = 0 K 0 K = - 459.67 °F = - 273.15 °C

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.

14 TEMPERATURE

Determine the lower fixed point (Tb)

Determine the upper fixed point

(Ta)

Melting point of ice at 1 atm

Divided between Ta and Tb

Every part = temperature per unit

Boiling point of pure water at 1 atm

Thermometer

Thermometer Calibration

15 TEMPERATURE

Thermometer Scale

Comparison of upper point and lower point for each temperature

scale CELCIUS REAMUR FAHRENHEITKELVIN

100 °C

0 °C 0 ° R

0 ° F

32 °F

80 °R 212 °F 373 K

273 K

O K = -273 ◦C

C : R : F : K 100 : 80 : 180 : 1005 : 4 : 9 : 5

Upper point

Lower point

COMPARISON SCALE

Absolute zero

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

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 TEMPERATURE

Tx = temperature of thermometer XXb = Lower point of thermometer XXa = Upper point of thermometer X

CONVERSION TEMPERATURE UNIT

Conversion Unit

Ty= temperature of thermometer YYb = Lower point of thermometer YYa = Upper point of thermometer Y

532)180

100

45( FT

100

45

180

32

FT

19 TEMPERATURE

1. What does 45°C equal if it is measured in a Fahrenheit thermometer?Given: TC = 45°C Question: TF = ?Solution:

9

EXAMPLE

ba

bC

ba

bF

CC

CT

FF

FT

0100

045

32212

32

FT

180100

4532 FT

3281 F1139

20 TEMPERATURE

EXAMPLE

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?

XbXa

XaTx

CbCa

CbTc

X

40°X

25°X

-10°X

Celcius 100°C

Tc =?

0°C

)10(40

)10(25

0100

0

Tc

1040

1025

100

Tc

50

35

100

Tc

10050

35Tc 235 C70

2

21 TEMPERATURE

Temperature unit conversion

Celcius to Fahrenheit scale

Celcius to Reamur scale

Celcius to Kelvin scale

Do Conversion unit of temperature below.

1. 40 °R = …………… °C2. 10°C = ……………. °F3. -40°C = …………….°F4. 27 °C = ……………… K5. 283K = ……..………. °F6. Thermometer A and B are

used to measure temperature of an object. What is Y when thermometer A shows 100° A? 50°A 20°B

320°B

Learning Check

Solution

1. 40 °R = 50 °C2. 10°C = 50 °F3. -40°C = -40°F4. 27 °C = 300 K5. 283K = 50 °F6. Thermometer A and B are

used to measure temperature of an object. What is Y when thermometer A shows 100° A?

50°A 20°B

320°B

24 TEMPERATURE

Kinds of Thermometer

• Liquid-in-glass thermometer• Gas thermometer• Bimetal thermometer• Pyrometer• Platinum thermometer• Thermocouple thermometer

Conversion Unit

www.tyas-physics.blogspot.com

25 TEMPERATURE

Alcohol as thermometric liquidAdvantages Weakness

It has a regular thermal expansion It wets the tube wall

It has a large coefficient of thermal expansion

It has a low boiling point (80°C) It is unsuitable to measuring high temperature

It has low freezing point (-115°C), it is suitable for measuring low temperature

It has a high specific heat capacity, so it needs a high energy to raise temperature

Liquid thermometer

Liquid-in-glass thermometer glass tube filled with liquid (often mercury

or alcohol) that expands/contracts

Alcohol and mercury have their own advantages and weakness.

26 TEMPERATURE

Mercury as thermometric liquid

Advantages Weakness

It is easy to see, have a shining color

It is very expensive

It is not wets tube wall It is a poisonous substance

It adapts the ambient temperature easily

Unsuitable for measuring a very low 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)

Liquid thermometer

27 TEMPERATURE

Kinds of thermometer

Gas thermometer

Bimetallic 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.

28 TEMPERATURE

Thermocouple thermometer

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

29 TEMPERATURE

Platinum thermometer Thermometer that

measures temperature by changes in the resistance of a spiral of platinum wire

Kinds of thermometer

Pyrometer An instrument for

measuring high temperatures (over 60000C)

It used to measure thermal radiation

30 TEMPERATURE

Kinds of liquid Thermometer

• Clinical Thermometer• Wall Thermometer• Maximum and Minimum Six-Bellani

Thermometer• Laboratory Thermometer

31 TEMPERATURE

Kinds of thermometer

Clinical 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)

Wall Thermometer

Used to measure the air temperature of a room

32 TEMPERATURE

Kinds of thermometer

Maximum- Minimum 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.

Laboratory Thermometer Used for laboratory

purpose

The Kinds of thermometer