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Heat - Coggle Diagram

- - - - Vibration of particles
        
        All matters are made up of particles
        
        Vibration of particles is a slow process of heat transfer
        
        When heated, the particles gain heat energy and vibrate more vigorously.
        
        In solids, the particles are closely packed together and can only vibrate at their fixed positions
        
        Solids conduct heat better than liquids and gases .
        
        That is because the particles in solids are closely packed together than those in liquids and gases
        
        As a result, it is easier for the particles to cause their neighboring particles to vibrate virgorously
        
        These particles will then cause the neighboring particles to vibrate too
        
        Hence, heat energy is transferred from one particle to the next medium
      - motion of free electrons
        
        In metals, there are free electrons that can move about freely.
        
        During heating, these free electrons help to transfer heat energy from the heated region to a cooler region quickly.
        
        The presence of these free electrons make the metals much better heat conductors than non-metals such as plastics, wood or glass.
        
        The different metals conduct heat at different speeds.
        
        It is a fast process of heat transfer
    - - Handles of the cooking utensils are made of insulators so that the users can be protected from scorching when holding them during cooking
      - A woolen jacket is used to trap air.
        
        Both wool and air are insulators that can prevent heat loss from the body to the cold surroundings
    - - Cooking utensils are made of metals such as iron, copper or aluminum because they can conduct heat quickly to cook the food.
      - Cooking utensils are made of metals such as iron, copper or aluminum because they can conduct heat quickly to cook the food.
      - The heating element in electric kettles is made of metal because it can conduct heat quickly to heat up water.
  - - - Cannot be in solid or vacuum
    - - This is called a convection current
    - - The particles in fluids are able to move freely,
        
        However, the particles in solids are not able to move freely
        
        Hence, they can only vibrate at their fixed position
        
        This allows the particles to transfer heat from one region to another by convection
  - - - This mode of heat transfer does not require a medium
        
        Allowing it to take place in a vacuum
    - - Heat energy from infrared radiation is called radiant heat
    - - Radiation of heat moves in all direction
    - - Poor emitter: White, Shiny, Smooth
      - Good emitter: Black, Rough
    - - Good absorber: Black, Rough
      - Poor absorber: White, Shiny, Smmoth
    - - Poor reflector: Black, Rough
      - Good reflector: White, Shiny, Smooth
    - - 1) Surface area of an object.
        
        If an object has a larger surface are, the rate of heat transfer.
      - 2) Surface temperature of an object.
        
        If the surface of an object has a higher temperature, it will radiate heat at a higher temperature
      - 3) Color and texture of an object.
- - - - Substances in same physical state have different rates of expansion and contraction too.
        
        For example
        
        Iron
        
        Iron expands and contracts during heating or cooling but not as quick as brass
        
        Brass
        
        Brass expands and contracts faster than iron during heating or cooling.
    - - The vigorous motion push one another further apart.
        
        Since the mass remains unchanged, the ratio mass over volume decreases.
        
        This causes density to decrease
        
        This increases the space they occupy
      - This then causes the motion to increase
  - - - Rate of contraction and expansion
        fast ------>slow
        gases liquids solids
    - - The less vigorous motion makes them become closer to one another.
        
        This decreases the space they occupy
        
        Since the mass remains unchanged, the ratio of mass over volume increases.
        
        Hence, the density increases
- - - - It prevents the setup of convection current
        
        Reduces heat loss by CONVECTION
    - - Air is a good insulator of heat
        
        Reduces heat loss by CONDUCTION
    - - It does not have any particles
        
        Reduced heat loss by CONDUCTION and CONVECTION
    - - Silvery wall reflects radiant heat back into the liquid
        
        Reduces heat loss by RADIATION