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 kinkRead More