introduction to heat. equalities of heat hot and cold objects Temperature table-temp. and heat heat fixed points temperature scales thermometers-making,intro.,types, conversation of scales Hd Pictures

4. HOT COLD

9. We can usually get a rough idea of how hot or cold an object is by touching it . But, the sense of touch is not very accurate. Also, when an object is extremely hot or extremely cold we cannot touch it. We, therefore measure the temperature with the help of a device called THERMOMETER. The earliest version of Thermometer was developed by Galileo. TEMPERATURE MEASUREMENT

11. A Mercury thermometer is used in Tropical & temperate climates.ALCOHAL THERMOMETER MERCURYTHERMOMETER

12. UPPER &LOWER FIXED POINTS LOWER FIXED POINT OF A THERMOMETER UPPER FIXED POINT OF A THERMOMETER

13. MAKING OF A THERMOMETER A Thermometer consists of a Capillary tube with a small bulb at its end. The bulb & part of the tube are filled with a liquid and the upper end of the tube is sealed so that the liquid does not evaporate. The space above the liquid in the capillary is evacuated so that the liquid expands freely. Mercury or Alcohol is used as Thermometric Liquids.

15. Celsius & Fahrenheit scales

16. Temperatures

17. Amazing Facts – Highest recorded Human body Temperature ! Did you know, that the highest recorded human body temperature was : 115.7oF (46.5oC) Very amazingly, the guy survived to talk (and brag) about it. According to the Guinness Book of World Records (New York: Bantam Books, 2000, p. 263), the person with the highest body temperature who lived to tell about it is Willie Jones. On July 10, 1980, Mr. Jones was admitted to the hospital with heatstroke. His temperature was 115.7oF (46.5oC). After 24 days in the hospital, he was discharged.

18. The lowest recorded body temperature with a full recovery was 56.6 degrees Fahrenheit, (13.7 degrees centigrade). This was the temperature of Anna Bagenholm who found herself trapped under ice for 80 minutes in May 1999 while skiing with friends in Norway.

19. INTER-CONVERSION OF SCALES We can covert temperature from the Fahrenheit scale of the Celsius scale and vice versa, by using the following formulas: For getting Fahrenheit °F=(9/5*C)+32 For getting Celsius °C=(F-32)*5/9

20. EXAMPLES CONVERT 104°F TO CELSIUS SCALE 104°F TO CELSIUS °C=(F-32)*5/9 =(104-32)*5/9 =72*5/9 =40 40C TOFAHRENHEIT

25.  Some looks of Thermometers DIGITAL THERMOMETER GALILEO THERMOMETER

26. TRANFER OF HEAT We know that HEAT always flow from Higher temperature to a lower temperature. The Hotter body loses heat & the colder body gains it. This phenomenon of Transfer of Heat from a Hotter body to Colder body is known as HEAT TRANFER. There are 3 different processes by which Heat Transfer can take place. They are : 1-CONDUCTION 2-CONVECTION 3-RADIATION

27. CONDUCTION It is the transfer and distribution of heat energy from atom to atom within a substance. For example, a spoon in a cup of hot soup becomes warmer because the heat from the soup is conducted along the spoon. Conduction is most effective in solids-but it can happen in fluids. Fun fact: Have you ever noticed that metals tend to feel cold? Believe it or not, they are not colder! They only feel colder because they conduct heat away from your hand. You perceive the heat that is leaving your hand as cold.

30. CONVECTION It is the transfer of heat by the actual movement of the warmed matter. Heat leaves the coffee cup as the currents of steam and air rise. Convection is the transfer of heat energy in a gas or liquid by movement of currents. (It can also happen is some solids, like sand.) The heat moves with the fluid. Consider this: convection is responsible for making macaroni rise and fall in a pot of heated water. The warmer portions of the water are less dense and therefore, they rise. Meanwhile, the cooler portions of the water fall because they are denser.

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