Ch – 4 Heat

Important points:

  • The measure of the degree of hotness of an object is known as “temperature“.
  • Temperature can be measured with the help of thermometer.
  • The thermometer that is used to measure our body temperature is known as clinical thermometer. It ranges between 35 degree Celsius to 42 degree Celsius. It consists of a long, narrow, uniform glass tube with a bulb at its end. The bulb consists of mercury.
  • Precautions to be taken while reading clinical thermometer are:
    • It should be washed before and after use, preferably with an antiseptic solution.
    • Ensure that before use the mercury level is below 35 degree Celsius.
    • Read the thermometer keeping the level of mercury along the line of sight.
    • Handle the thermometer with extreme care.
    • Never hold the thermometer by bulb while reading it.
    • Avoid keeping the thermometer near a flame or in sun.
  • The thermometer that is used to measure the temperature of other objects is known as Laboratory thermometer. It ranges between -10 degree Celsius to 110 degree Celsius.
  • Precautions to be taken while using a laboratory thermometer:
    • Always keep it upright.
    • The bulb should be covered entirely by the substance of which the temperature is to be measured.
  • The maximum and minimum thermometer is used to measure the maximum and minimum temperatures of the previous day.
  • The normal temperature of a human body is 37 degree Celsius.
  • Digital thermometers do not use mercury.
  • The kink near the bulb in the clinical thermometer prevents mercury level from falling on its own.
  • The flow of heat from a body at a higher temperature to a body at a lower temperature is known as transfer of heat.
  • The transfer of heat takes place in three ways: Conduction, Convection and Radiation.
  • The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction. It takes place generally in solids.
  • The transfer of heat in liquids and gases usually take place by convection.
  • In radiation, no medium is required for the transfer of heat.
  • Insulators do not allow heat to pass through them easily.
  • Conductors allow heat to pass through them easily.

Published by Priya Prakash

In the midst of winter, i found there was within me an invincible summer ~ Albert Camus

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