# Temperature and Thermometers

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Temperature and Thermometers. Do Now – Copy and Complete the table Evaporation and Condensation.flv. Learning today. What is a thermometer scale What Lower and Upper fixed points are Thermal equilibrium Different types of thermometer. What is Temperature?. Measuring Temperature. - PowerPoint PPT Presentation

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Temperature and Thermometers

Temperature and Thermometers Do Now Copy and Complete the table Evaporation and Condensation.flvEvaporation Boiling Change of stateWhere Temperature Learning today What is a thermometer scale What Lower and Upper fixed points areThermal equilibriumDifferent types of thermometerWhat is Temperature?

Measuring TemperatureIn 1742, Andreas Celcius created the temperature scale that is known by his name.

Ive never heard of the Andreas scale, it must be a European thing5Celsius ScaleIn the Celsius scale, a value of zero degrees is assigned to the freezing point of water, and a value of one hundred degrees to the boiling point of water.

0OC Freezing point of water lower fixed point 100OC boiling point of water upper fixed point At normal atmospheric pressure

6Celsius ScaleA temperature scale is a measure of the level of hotness. Everyday temperatures are measured on the Celsius scale.0OC Freezing point of water lower fixed point 100OC boiling point of water upper fixed point At normal atmospheric pressure warm tea in an aircraft.

7TemperatureTEMPERATURE determines the direction of flow of thermal (heat ) energy between two bodies in thermal contact Heat flows from where its hot to where its not

until the two bodies reach thermal equilibrium the same temperature

HOTCOLD 8Thermal equilibriumTwo bodies in thermal contact will eventually reach the same temperature. The two bodies are now said to be in thermal equilibrium.WARMWARM9TemperatureTemperature is also a measure of the average random kinetic energy of the particles in a substance.Note that they are not all travelling at the same speed.10TemperatureThe hotter the temperature, the faster the average speed of the particlesNote that they are not all travelling at the same speed.11Do Task

Finish questions 1-3 page 101Read about the Kelvin scale Making a Celcius thermometerPlace a glass tube containing mercury in a mixture of ice and water and labelling the position of the mercury as zero.0C13Making a Celcius thermometerThen place the tube in boiling water and label the new length as 100C the upper fixed point0C100C14Making a Celcius thermometerFinally the range from 0 to 100 is subdivided into equal intervals.0C100C15Task

Making a thermometer answer the questions Temperature and ThermometersCommon thermometers used today include the liquid-in-glass type and the bimetallic strip and thermocouples.

Make notes on liquid in glass thermometer and a thermocouple Thermocouple ThermometerTwo different metals are joined to form two junctions. A temperature difference causes a tiny voltage which makes a current flow. Thermocouples are quick to respond to temperature changes a wide range -200oC to 1100oC can be connected to computers

Liquid in glass thermometer Nearly all liquids expand slightly when heated. Thermometers use alcohol or mercury Mercury is toxic hence no longer used in schoolsSchool alcohol thermometers measure between -10oC to 110oC

Measuring temperature The thermometer has to be placed in thermal contact with whatever is being measured until the thermometer and object are in thermal equilibrium.

Stick in your books Thermometer Terms Sensitivity Some thermometers are more sensitive, the thread of liquid moves further. The narrower the tube the higher the sensitivity.Range Thermocouple -200oC to 1100oCAlcohol thermometer -10oC to 110oC for the school thermometers but can measure lower temperatures. Mercury high temp of 500oCLinearity alcohol and mercury thermometers agree at the fixed points but not those in between as they have different expansion characteristics.

Do questions 1&2 page 105 followed by aGraph question. Kelvin TemperatureLord Kelvin1824-1907

Kelvin TemperatureKelvin temperature is proportional to the average random kinetic energy of the particles in a substance.Note that they are not all travelling at the same speed.25Absolute/Kelvin temperature and CelsiusT (in Kelvin) = T (in degrees Celcius) + 273

Just to mention for now that zero Kelvin is the lowest possible temperature.26Measuring temperature The thermometer has to be placed in thermal contact with whatever is being measured until the thermometer and object are in thermal equilibrium.

Kelvin TemperatureLord Kelvin1824-1907

Kelvin TemperatureKelvin temperature is proportional to the average random kinetic energy of the particles in a substance.Note that they are not all travelling at the same speed.29Absolute/Kelvin temperature and CelsiusT (in Kelvin) = T (in degrees Celcius) + 273

Just to mention for now that zero Kelvin is the lowest possible temperature.30

Do questions 1&2 page 103Pressure and Temperaturehttp://phet.colorado.edu/sims/ideal-gas/gas-properties_en.jnlp

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