Lecture_b_270663.pptx
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This document discusses different methods of heat transfer - conduction, convection, and radiation. It defines key terms like heat, temperature, and latent heat. It explains concepts like specific heat of fusion and vaporization. It also covers the phenomenon of regelation where ice can melt under pressure and re-freeze when pressure is removed, and how this relates to latent heat. It notes that boiling point decreases but melting point increases at higher altitudes due to lower atmospheric pressure.
Lecture_b_270663.pptx
- 1. Lecture - 1
- 3. Hot Body Cold Body HEAT CONVECTION RADIATION CONDUCTION
- 4. CONDUCTION PARTICLES DO NOT MIGRATE
- 6. RADIATION PARTICLES (medium) NOT REQUIRED Nuclear Blast
- 10. CONDUCTION CONVECTION RADIATION Chocolate in your hand melts
- 12. HEAT TEMPERATUR E 1. It is measure of the total amount of energy of an object. 1. It is a measure of degree of hotness or coldness of an object 2. SI unit is joule (J) 2. SI unit is kelvin (K) 3. Heat is always positive. 3. Temperature can be positive or negative. DIFFERENCE BETWEEN HEAT AND TEMPERATURE
- 13. 10 20 30 40 50 60 70 80 90 100 属C 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (Minutes) (0, 0) Ice + Water (Solid - Liquid) A B C Liquid Gaseous state D The amount of heat energy absorbed at constant temperature by unit mass of a solid to convert into liquid phase is called the SPECIFIC LATENT HEAT OF FUSION. LATENT HEAT The amount of heat energy absorbed at constant temperature by unit mass of a liquid to convert into gaseous phase is called the SPECIFIC LATENT HEAT OF VAPORIZATION. 0属c 100属c Heat utilized for melting ice Heat utilized for converting water to steam No change in temperature Temperature of water rises At constant temperature Solid phase to Liquid Phase At constant temperature Liquid phase to Gaseous Phase
- 14. 10 20 30 40 50 60 70 80 90 100 属C 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (Minutes) (0, 0) A B C D Is the concept of latent heat applicable during transformation of gaseous phase to liquid phase and from liquid phase to solid phase? Ans. Yes, the concept of Latent heat is applicable in both the cases. The heat energy will be evolved from the substance. Where does the latent heat go during these transformation? Ans. The Latent heat is rejected into the atmosphere.
- 15. REGELATION
- 16. REGELATION The phenomenon in which the ice converts to liquid due to applied pressure and then re-converts to ice once the pressure is removed is called REGELATION. Pressure increases Melting point decreases Ice becomes water Pressure decreases Melting point increases Water becomes ice
- 17. In the given experiment, the wire moves through the ice slab. However, the ice slab does not break. Why? (i) The melting point of ice becomes lower than 0属C due to the applied pressure on the wire. (ii)So Ice gets converted into water and the wire gets moved through the ice slab. (iii) Once the pressure is removed the water becomes Ice again. (iv) Hence, the wire moves through the Ice slab without breaking it. Ans.
- 18. Is there any relationship of latent heat with the regelation? (i) During regelation, there is change of state. (ii)The amount of heat energy absorbed or released during change of state is called Latent heat. (iii) Hence, latent heat is one of the factors affecting Regelation. You know that as we go higher than the sea level, the boiling point of water decreases What would be effect on the melting point of solid? (i) As we go higher than sea level, the atmospheric pressure decreases. (ii)So melting point of solid increases .i.e solid will melt at a higher temperature. Ans. Ans.