|Heat travel through solids by conduction||Heat travel through liquids by convection|
|Heat travel through atoms/molecules which are very close.||Heat travel through actual movement of molecules.|
Silver, Copper, Aluminium, Brass, Iron etc. are good conductors of heat.
Why silver teapot is preferred to black teapot?
Silver teapot will not radiate heat quickly and thus remain hot for longer period.
What do we mean by convection?
Convection is the transfer of heat energy from one place to another by the movement of the substance itself.
Explain why cold water sinks when it is surrounded by warm water?
Cold water is heavier than warm water. That’s why cold water sinks when it is surrounded by warm water.
Explain why gases are poor conductors of heat?
Gases are very poor conductors of heat because their particles are widely separated so that collisions do not occur frequently to enable efficient energy transfer.
What do we mean by heat conductors?
Materials that conduct heat through them are called heat conductors. Silver, Copper, Aluminium, Brass, Iron etc. are good conductors of heat.
|Good Conductors||Poor Conductors|
|Heat can travel through them.||Heat cannot travel through them.|
|Silver, Copper, Aluminium, Brass, Iron etc. are good conductors of heat.||Vacuum, Air, Cork, Wood, Water, Glass etc. are poor conductors are heat.|
· Vacuum flask consists of two flasks, inserted one into the other and joined at the neck.
· The space between two flasks is evacuated vacuum, prevents heat transfer by conduction and convection.
· Heat transfer by radiation is reduced by silver coating flask surface with pure aluminum.
Explain the process of convection with the help of experiment.
· Take a beaker and fill it with water.
· Put some crystals of Potassium permanganate in it.
- Heat up the beaker with burner.
What do you mean by conduction? Explain how heat is transferred through solids, particularly metals.
· The movement of heat through solid such as metals is called conduction.
· Take a metal bar and put some wax on its one end.
- Heat other end.
- After sometime wax start melting.
What is meant by radiation? How will it be explained?
· Radiation is the transfer of heat energy through vacuum or any transparent media in the form of electromagnetic waves.
· For example heat of sun reaches us passing through space (vacuum).