Heat Class 7 PPT

 Page 1


CHAPTER - 4 
 
HEAT 
Page 2


CHAPTER - 4 
 
HEAT 
1) Hot and cold :- 
    In our daily life we come across a number of objects. 
Some of them are hot and some of them are cold. 
  Eg :- Tea is  hot and ice is cold. 
   Some objects are hotter than others and some are colder 
than others. 
   We often decide which object is hotter than the other by 
touching the objects. 
   We cannot always rely on our sense of touch to decide 
how hot or how cold an object is. 
  The hotness of an object is measured by its temperature. 
  Temperature :- is a measure of the degree of hotness of an 
object. 
  Temperature is measured by a device called thermometer. 
  
Page 3


CHAPTER - 4 
 
HEAT 
1) Hot and cold :- 
    In our daily life we come across a number of objects. 
Some of them are hot and some of them are cold. 
  Eg :- Tea is  hot and ice is cold. 
   Some objects are hotter than others and some are colder 
than others. 
   We often decide which object is hotter than the other by 
touching the objects. 
   We cannot always rely on our sense of touch to decide 
how hot or how cold an object is. 
  The hotness of an object is measured by its temperature. 
  Temperature :- is a measure of the degree of hotness of an 
object. 
  Temperature is measured by a device called thermometer. 
  
Clinical thermometers 
Page 4


CHAPTER - 4 
 
HEAT 
1) Hot and cold :- 
    In our daily life we come across a number of objects. 
Some of them are hot and some of them are cold. 
  Eg :- Tea is  hot and ice is cold. 
   Some objects are hotter than others and some are colder 
than others. 
   We often decide which object is hotter than the other by 
touching the objects. 
   We cannot always rely on our sense of touch to decide 
how hot or how cold an object is. 
  The hotness of an object is measured by its temperature. 
  Temperature :- is a measure of the degree of hotness of an 
object. 
  Temperature is measured by a device called thermometer. 
  
Clinical thermometers Digital thermometers 
Page 5


CHAPTER - 4 
 
HEAT 
1) Hot and cold :- 
    In our daily life we come across a number of objects. 
Some of them are hot and some of them are cold. 
  Eg :- Tea is  hot and ice is cold. 
   Some objects are hotter than others and some are colder 
than others. 
   We often decide which object is hotter than the other by 
touching the objects. 
   We cannot always rely on our sense of touch to decide 
how hot or how cold an object is. 
  The hotness of an object is measured by its temperature. 
  Temperature :- is a measure of the degree of hotness of an 
object. 
  Temperature is measured by a device called thermometer. 
  
Clinical thermometers Digital thermometers 2) Measuring temperature :- 
  The thermometer that measures the temperature of our 
body is called clinical thermometer. 
  A clinical thermometer has a long narrow glass tube. It has 
a bulb at one end containing mercury. It has a scale called 
celsius scale marked in 
0
C (degree celsius). A clinical 
thermometer reads temperature from 35 
0
C to 42 
0
C.The 
clinical thermometer has a small kink near the bulb to 
prevent the mercury level from falling down. 
  The normal temperature of the human body is 37 
0
C. 
   
mercury 
Clinical thermometer 
kink 
      kink