Question

plz explain me conduction of heat transfer

Answer 1

someone pours you a hot cup of coffee, you're likely going to pick it up from the handle instead of around the main part of the mug. This is because the coffee mug will conduct heat from the hot liquid inside to your hand. This direct transfer of heat from one object to another is called conduction.

The coffee mug transfers heat well, as do many other substances, including metal. You certainly wouldn't touch a hot metal pan on the stove or hold a nail over a flame without some sort of protective glove, because you know that the heat from the metal will quickly transfer to your hand and burn you. It makes sense then that these substances that conduct heat well are called conductors.

Some substances are very bad at transferring heat, and these are called insulators. Wood is a very good insulator (therefore a very poor conductor), which is why your metal pot on the stove may have a wooden handle. You can do a little experiment to see this in action. If you have an area in your house where wood floor meets some tile, put a bare foot on each one. You'll find that the tile floor feels cooler, but both floors are actually the same temperature! The tile is a much better conductor of heat than the wood, so it transfers the heat from the bottom of your feet better than the wood does, making your foot feel cold. Air is also a very poor conductor, which is why you can reach your hand in the oven to grab a dish without burning yourself (unless you forget your oven mitts and grab the dish itself!).

Your house is insulated with something like rock wool or fiberglass because these substances are poor conductors of heat. Imagine how cold your house would be if there was no protection from the cold outside during winter, or how hot it would be if you weren't protected from the heat outside in the summer! Interestingly, though, insulators don't actually stop the flow of heat, just slow the transfer considerably. That's why you still need to run your heat in the winter and A/C in the summer - just not as much as if you had no insulation at all.

Answer 2

Conduction transfers heat via direct molecular collision. An area of greater kinetic energy will transfer thermal energy to an area with lower kinetic energy. Higher-speed particles will collide with slower speed particles. The slower-speed particles will increase in kinetic energy as a result. Conduction is the most common form of heat transfer and occurs via physical contact. Examples would be to place your hand against a window or place metal into an open flame.