HEAT - POST-7

HEAT - Post 7

 

  Heat : CONDUCTION ( part-1)

Welcome back to our Science lesson. During the previous class you learnt about the difference between a clinical thermometer and a laboratory thermometer. Today dear boys we will learn about how heat gets transferred from one body to another.

 There are 3 modes by which heat is transmitted or transferred. They are : CONDUCTION, CONVECTION and RADIATION .

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 Today we will  learn about conduction:

 

I am quite sure at some point of time you must have  touched a spoon   placed in  a vessel / utensil/ patheela on the gas stove.. YOU FOUND it HOT!!! And let go of it immediately.

How did   the spoon become hot   ?
  

  



 Think a moment…  HEAT got transferred from the vessel on the gas stove to the spoon and that' s the reason  why the spoon got heated.


 Click on the link below:
 https://www.britannica.com/video/151062/Explanation-heat-transfer





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You have learnt that a solid has a definite shape because the molecules are closely packed.

i)    When  a solid is heated the molecules closest to the source of heat  receive a lot of energy and vibrate about their mean position. IT is almost as if they are jumping around in the very same place. This heat energy is transferred to the molecule closest to it. That molecule will transfer energy to the molecule next to it and so  this process continues.

https://www.youtube.com/watch?v=Xdh_RoQiEog


ii)     The two objects  should be at  DIFFERENT TEMPERATURES.



 HEAT CONDUCTION can take place only under two CONDITIONS   :

•  The two objects  should be at  DIFFERENT TEMPERATURES. 
• The two objects  should be in DIRECT CONTACT

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 (Detailed explanation)

In the atomic theory solids, liquids and gases are made of tiny particles called "atoms". The temperature of the material measures how fast the atoms are moving and the heat measures the total amount of energy due to the vibration of the atoms.
Conduction can happen when one part of a material is heated. The atoms in this part vibrate faster and are more likely to hit their neighbors. The collisions cause those atoms also to move faster, passing the heat energy to them. In this way the energy travels through the solid. (Rather like the way energy passes along a set of tumbling dominos).
The atomic picture also helps explain why conduction is more important in solids: in solids the atoms are close together and unable to move around. In liquids and gases the particles can move past each other, so the collisions are less common.

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View the following links  ( two links)so as to learn more about conduction:

https://youtu.be/1jNwOAw_CHk

https://youtu.be/w_IbPRNZ6ho

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 DO THE QUESTIONS GIVEN BELOW IN YOUR SCIENCE NOTEBOOK

Q 17) List the  methods by which heat can be transferred.
A) The 3 modes by which heat can be transferred are:

•  Conduction
• Convection
• Radiation

Q 18)Define  ConductioN: 
ANS:Conduction is the process by which heat is transferred from one particle to another ( in the direction of the lower temperature) without the actual movement of particles.
 

Q 19) Write two conditions  that are required for the CONDUCTION of HEAT.

• The two objects should be in DIRECT CONTACT
• The two objects must be at different TEMPERATURE

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H.W - The Q& Answers in this blog  (given in  green) are to be written out in your note book and learnt.