Doppler Effect                                            This effect, where there is a change in
                                                          frequency and wavelength, is called the
  It is named after the Austrian physicist               Doppler Effect.
   Christian Doppler, who proposed it in                 When a source moves towards an
   1842 in Prague.                                        observer, the observed wavelength
  You may have noticed that when an                      decreases and the frequency increases.
   ambulance or police car goes past, its siren          When a source moves away from an
   is high-pitched as it comes towards you,               observer, the observed wavelength
   then becomes low-pitched as it goes away.              increases and the frequency decreases.
                               HEAT & TEMPERATURE
Heat                                                     Body temperature can rise to 105 degrees
                                                          if working outside in a heat wave. Death
  It is a form of energy and measures the                occurs usually when a body temperature
   total energy of all molecules in the                   reaches 107.6.
                                                         You’ll lose weight in the heat.
  It is a total kinetic energy of all molecules
   in a substance.                                       The average temperature on Mars is -63C.
  Its units are Calorie (cal), Kilocalorie              Good heat conductors: Gold, Copper,
   (kcal) or Joule (J). Its CGS unit is the erg           Silver, Iron, Aluminum, Nickel, Zinc &
   = 10-7 joule.                                          most other metals
  1 cal = 4.18 joule                                    Bad heat conductors: Plastic, Bakelite,
  1 kcal = 1000 cal                                      Styrofoam, Air, Water, Rubber, Cotton,
                                                          Silk, Marble, Wood, Mica
                                                         When lightning strikes it can reach up to
  It is a measure of degree of hotness or                30,000 degrees Celsius (54,000 degrees
   coldness of a body.                                    Fahrenheit)
  The unit of degree Celsius or Kelvin or               Room temperature is defined as between
   degree Fahrenheit.                                     20° to 25°C (68° to 77°F)
  Two bodies cannot be in thermal                       When water freezes it expands by 9%
   equilibrium if they are at different
                                                         Hot water freezes quicker than cold water
  It is a measure of average kinetic energy             Normal body temperature is 37°C (99°F)
   of molecules in a substance.                          The center of the Sun is approximately 15
  The formula relating all temperature scales            million°C
    C F  32 R K
                  
    5      9      4 5                                    It is an instrument for measuring
Facts about Heat and Temperature                         Optical pyrometer : It determines the
                                                          temperature of a very hot object by the
  The highest temperature ever recorded on               color of the visible light it gives off.
   Earth was 136 Fahrenheit (58 Celsius) in              Radiation pyrometer : It determines the
   the Libyan desert. The coldest temperature             temperature of an object from the radiation
   ever measured was -126 Fahrenheit (-88                 (infrared and, if present, visible light)
   Celsius) at Vostok Station in Antarctica.              given off by the object.