1.1 Temperature and thermometer Galileo thermometer Temperature Temperature scale Thermometers Calibrating thermometers Particle motion and temperature Check-point 1 1 2 3 4 ? E 5 1.1 Temperature and thermometer

This is a Galileo thermometer. Look at the lowest floating sphere. It tells us the temperature! Video 1.1 Temperature and thermometer

Can I determine the temperature without using thermometer? Galileo thermometer Can I determine the temperature without using thermometer? Is it good? Why? 1.1 Temperature and thermometer

1 Temperature Temperature tells us how hot/cold a body is. To measure and compare temperatures of different bodies accurately, we need... temperature scale thermometers Temperature scale ~ ruler scale 1.1 Temperature and thermometer

2 Temperature scale Choosing 2 readings of temperature, T1: lower (ice) point (pure melting ice at normal atm pressure) T2: upper (steam) point (steam over pure boiling water at normal atm pressure) melting ice boiling water . . . divide n divisions . . . . . . 1 division  degree 1.1 Temperature and thermometer

2 Temperature scale Celsius scale Most commonly used temperature scale Degree: C Ice point  0 C, steam point  100 C 0 C 100 C 100 divisions 1.1 Temperature and thermometer

3 Thermometers With a temperature scale, temperatures can be measured accurately by thermometers. bulb filament 2500 C melting ice 0 C boiling water 100 C C surface of Sun 5000 C Bunsen flame 1000 C body 37 C freezer –20 C 1.1 Temperature and thermometer

Each of them uses a property that changes with temperature. 3 Thermometers There are many types of thermometers. Each of them uses a property that changes with temperature. 1.1 Temperature and thermometer

a Liquid-in-glass thermometers liquid thread liquid bulb narrow glass tube T , liquid expands T , liquid contracts Length of the thread  temperature 1.1 Temperature and thermometer

a Liquid-in-glass thermometers Alcohol-in-glass Mercury-in-glass T > –115 °C T < 357 °C freezing point of alcohol boiling point of mercury Slow response Quick response Non-poisonous Poisonous 1.1 Temperature and thermometer

b Other thermometers Rotary thermometer (expansion of metals) Thermistor thermometer (resistance) Infra-red (IR) thermometer (emission of IR) Liquid crystal thermometer (colour) 1.1 Temperature and thermometer

4 Calibrating thermometers Mark the liquid level Mark the liquid level Put in melting ice Put in boiling water 1.1 Temperature and thermometer

4 Calibrating thermometers Simulations 1.1 Temperature and thermometer

5 Particle motion and temperature a Kinetic Theory Theories explain/predict phenomena. Kinetic theory phenomena in heat predicts explains 1.1 Temperature and thermometer

There is attractive force between particles. a Kinetic Theory E All matters are made up of tiny particles which are constantly in motion. There is attractive force between particles. close particles distant particles weak attraction strong attraction e.g. in a gas... 1.1 Temperature and thermometer

a Kinetic theory Particles of... solid liquid gas very close  strong attraction less close  strong attraction far apart  weak attraction fixed positions; can vibrate only irregular positions; can change position irregular positions; can move freely at high speed 1.1 Temperature and thermometer

a Kinetic theory Simulation solid gas liquid fixed volume and shape fixed volume but irregular shape irregular volume and shape Simulation 1.1 Temperature and thermometer

b Interpreting temperature by kinetic theory Motion of the particles in a body depends on its temperature. T   particles vibrate more rapidly/move faster T   particles slow down  temp. of a body  ave. KE of particles Particles of bodies have the same ave. KE  bodies have the same temp. 1.1 Temperature and thermometer

Check-point 1 1 Which of the following… Determine which of the… 4 When Karen puts a... 1.1 Temperature and thermometer

Which of the following about the Celsius scale is incorrect? Check-point 1 – Q1 Which of the following about the Celsius scale is incorrect? A Lower fixed point = 0 C Upper fixed point = 100 C B (upper fixed point – lower fixed point)/100  each division is degree Celsius C It is the only temp. scale available. D T > 100 C and T < 0 C are OK. 1.1 Temperature and thermometer

Determine which of the following is different from the others. Check-point 1 – Q2 Determine which of the following is different from the others. A Clinical thermometers. B Rotary thermometers. C Alcohol-in-glass thermometers. D Thermistor thermometers. The resistance (not volume) of a thermistor changes with temp. 1.1 Temperature and thermometer

Which of the following is incorrect? Check-point 1 – Q3 E Which of the following is incorrect? A Gas particles are far apart and move at very high speeds. B Temp. rises  particles move faster C Temp. is a measure of total KE D Particles have same ave. KE  same temp. 1.1 Temperature and thermometer

... in boiling water mercury column: 26.1 cm Check-point 1 – Q4 ... in boiling water mercury column: 26.1 cm ... under her tongue mercury column: 12.0 cm … in melting ice mercury column: ?? cm 1.1 Temperature and thermometer

Check-point 1 – Q4 100 C  26.1 cm, 37 C  12.0 cm Let x be the length of mercury column in ice. By proportion, distance between 100 C and 37 C 100 – 37 = distance between 100 C and 0 C 100 – 0 ( ) – 12.0 ( ) – ( ) = 63 100 26.1 26.1 x x = 3.72 cm 1.1 Temperature and thermometer

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A mercury-in-glass thermometer Example 1 A mercury-in-glass thermometer An unmarked mercury-in-glass thermometer was put... in melting ice, mercury column = 4.5 cm in boiling water, mercury column = 22.0 cm in warm water, mercury column = 11.5 cm What is the temp. of warm water? 1.1 Temperature and thermometer

A mercury-in-glass thermometer Example 1 A mercury-in-glass thermometer In warm water, mercury column = 11.5 cm Graphical method: plot a calibration graph 11.5 Warm water is 40 C. 1.1 Temperature and thermometer

Example 1 100 divisions between 4.5 cm & 22.0 cm By proportion, A mercury-in-glass thermometer in melting ice, mercury column = 4.5 cm in boiling water, mercury column = 22.0 cm in warm water, mercury column = 11.5 cm 100 divisions between 4.5 cm & 22.0 cm By proportion, 11.5 – 4.5 Temp. of warm water =  100 22.0 – 4.5 = 40 C 1.1 Temperature and thermometer

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