1. Name : Mrs. Bharati Vivek Gorwadkar Roll No.: 16 Subject: Science Topic: Heat Prof. Incharge: Prof. Rajendra Thigle

2. Heat What is Heat? Heat is the form of energy that is transferred between two substances at different temperatures. Heat and temperature are often used interchangeably, but this is incorrect. Temperature is the measure of hotness or coldness of matter.

3. An object moves and gets displaced when force is applied to it. When displacement occurs, work is done. Energy is needed for doing work. If we observe pressure cooker on the gas, we hear the whistle after some time.

4. There is a water in the cooker. When water is heated it gets energy in the form of steam. So that the weight is lifted. It means that the water gets energy due to heat. This tells us that heat is a form of energy. From higher temperature To lower temperature Transfer of heat Temperature is an indicator of the heat in a substance.

5. Transfer of heat takes place in three ways: 1)Conduction 2)Convection 3)Radiation

6. 1.Conduction of heat

7. Put a pot of water on the hot stove. Once the water is good and hot (boiling or near boiling), carefully place 3 different spoons in the pot – one metal, one plastic or rubber, and one wooden spoon. The butter on the metal spoon almost immediately melted away; the butter on the wooden spoon melted some; meanwhile, the butter on the plastic spoon stayed firm much longer. That’s heat conduction at work. The heat was transferred by moving molecules within the spoons. The spoons themselves didn’t move, but their molecules did. This experiment also gives us some insight into what kinds of materials conduct heat well.

8. Convection of heat Take a beaker. Half Fill it with it water and heat it. Then add some crystals of potassium permanganate to the water. You will observe steams of coloured water moving upwards from the bottom of the beaker and then down again.

9. The water near the bottom gets heated first. Hot water is always lighter than cold water. Hence, the heated water goes straight upwards and the cold water goes down from the sides to take its place. Thus,heat is transferred upwards by means of currents called convection currents and the process is called convection. Convection takes place only in fluid mediums, that is, liquids and gases.

10. Radiation of heat Take two tin can of same size and shape. Paint one white and other black. Fill water up to the same level in both the can and close the lids. Place the can in the sun for an hour and then compare the temperature of the water in the two can by touching it.

11. The water in the black can is warmer than in the white can. This tells us that a black body absorbs more heat than a white body. Thermos flask consists of two thin glass bottles fitted one inside the other. A vacuum is created in the space between the two bottles by removing all the air from it. Here no medium is present for transmission of heat. The radiant heat is reflected back inside from the shiny surfaces. Hence the cold liquid remains cold and hot remains hot.

12. Good and bad conductors of heat Good conductors of heat & electricity

13. Bad conductors of heat & electricity

14. What is Heat? Explain transfer of heat with suitable example. Which are the different ways of transfer of heat? Define conduction, convection and radiation of heat. What is good and bad conductor of heat? Explain with suitable example.

15. Reference: www.google.com