Transfer of Thermal Energy
Thermal energy always flows from a region of higher temperature to a region of lower temperature.
Thermal energy is the same as heat energy
thermal equilibrium is when there is no temperature difference between the two regions
Thermal energy can be transferred by conduction,radiation and convection.but today i will just post on conduction:P
Conduction is the process of thermal energy transfer without any flow of the material medium.
-Conduction takes place in things like solids and liquids and gases.
-there are 2 types of conduction. one is free electron diffusion and the other is molecular vibration.
MOLECULAR VIBRATION->the way heat is mainly transported.
FREE ELCTRON DIFFUSION->it is the reason why metals are conductors while non metals are insulators[:
Different materials can conduct heat at different rates.there are good conductors like metal and poor conductors of heat like wood. Conduction takes place by when thermal energy is transferred,the particles nearer to the hot end will start to vibrate and will collide with the neighbouring particles,which causes them to vibrate too,which will increase the temperature.
the reason why metals are conductors and non metals are insulators is because of free electron diffusion. when metals heat,the free electrons move faster resulting in more kinetic energy. These fast-moving, energy carrying electrons diffuse or spread into the cooler end of the object by colliding with them hence heat is transferred.An experiment that can be done is:
1)Put a small piece of butter on an aluminium foil
2)light up a candle
3)Place the stick about 3 inches above the flame and start timing it.
4)When the butter melts and falls off, stop the stopwatch and record the time.
-Repeat this for the other 3 metal sticks(copper,zinc and iron)
3)Place the stick about 3 inches above the flame and start timing it.
4)When the butter melts and falls off, stop the stopwatch and record the time.
-Repeat this for the other 3 metal sticks(copper,zinc and iron)
WHY DO METALS HEAT UP FASTER THAN NON METALS?
Metals contain more free electrons which are able to move randomly between molecules than non-metals where there is less collision.This explains why the rate of heat transfer is faster in metals than in non-metals[:
Conduction in liquids and gases is due to the collision of molecules over each other,and the conduction rate is slower than in solids:D However,molecules in liquids and gases are less prone to collision as they are not closely packed.
Applications of conduction[:
-Good conductors of heat:
Cooking utensils
These cooking utensils are often made of aluminium or stainless steel.SOLDERING IRON RODS
These iron rod have a tip made out of copper as copper is a good coonductor.Insulators:
Handles of utensils
The handles of utensils are often made of poor conductors of heat like plastic or wood. Hence,when we pick up these utensils,we will not get burnt:D
The handles of utensils are often made of poor conductors of heat like plastic or wood. Hence,when we pick up these utensils,we will not get burnt:D
Table mat
These tables mats are made of cork so that when hot plates of food is placed on it,the tabe will not get burnt.
These tables mats are made of cork so that when hot plates of food is placed on it,the tabe will not get burnt.Woollen clothes
Woollen clothes ar meant to keep people warm on cold days(:
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