Tag Archives: conduction

Boil water in Paper bag

In ancient time before the invention of metal and clay pots. Humans had been boiling water in large cup shaped leaves. We know this is old method of boiling water but for fun and learning how it works we will boil water in a bag made out of paper.

boil-water-in-paper-bag

 

 

 

 

 

 

 

how-to-make

 

 

 

  1. Make a simple cup shaped paper bag. Keep the bottom area of the bag larger than the area of the fire of your gas stove
  2. Put your bag on stove and pour some water in it. Start fire gently and keep its flame level lower than the corner and sides of your bag. Otherwise sides of your bag may burnout. Wait until water starts to boil. If you have house hold thermometer use it to check water temperature.

explanation

 

 

 

Paper has ability to absorb water when you pour water in your paper bag, it absorbs some water which prevents it from burning and fire keeps the paper dry. In this way water that becomes hot goes to surface and cold water takes its place. This process continues as long as your bag has water.

Heat Transfer

Heat transfer Occurs when Temperature difference in the system exist. In our environment heat transfer occur all the day. Heat normally flows from higher temperature body to lower temperature body by three methods Conduction, Convection and Radiation.

heat-transfer

 

Conduction

When two Bodies of different temperature comes in contact with each other heat flows from flows from hot body to cold body by collision of the molecules.

In Solids molecules of hot body vibrate more frequently than cold body. When both bodies comes in contact with each other their molecules collide and some energy from hot body is transferred to cold body until both bodies attains same temperature

when you boil water on the gas stove heat is conducted to pot from fire.

Convection

It is Heat transfer that is caused by flow and diffusion of fluids (liquids, Gases) from higher temperature region to lower temperature region.

When water is boiled on gas stove heat is conducted by metal pot. Metal increase the temperature of water that is in contact with it. Hot water rise to surface  and replaced by cold water. This process continues and cause circular motion.

Radiation

In This process heat is transferred by electromagnetic waves known as light. This process is independent of material medium to transfer heat. In this way heat can be transferred through space. Sun transfer heat by radiation which we feel.