Zusammenfassung der Ressource
THERMAL ENERGY
- Effects of thermal energy
- Effects on matter
- Solids expands and contracts the least followed by liquid then gas.
- When cooled, solids, liqiuds and gases contract and decrease in volume.
- When heated, solids, liquids and gases expand and increase in volume
- Effects on everyday life
- Problems
- Laboratory glassware cracking when heated due to uneven expansion
- Telephone and electrical wires snapping on cold days due to contraction
- MRT and railway tracks wrap on hot days due to expansion
- Bridges cracking on hot days due to expansion
- Tiled and concrete pavements cracking on hot days due to expansion
- Water pipes cracking or bursting on hot days due to expansion
- Solutions
- Water pipes are built with expansion bends to allow space for espansion
- Laboratory glassware is made of Pyrex glass which expands very little when heated
- Telephone and electrical wires are hung loosely to allow space for contraction
- Bridges are built with rollers on one side to allow expansion
- Pavements and tiles have expansion gaps that allows space for expansion
- Transfer of thermal energy
- Conduction
- Conduction is the process of thermal energy transfer through a medium from one particle to another
- All matters are conductors of thermal energy
- Solids are generally better
conductors of thermal energy as
compared to liquid and gas
- Convection
- Convection is the
process in which
thermal energy is
transmitted by the
movement of liquid or
gas. It cannot occur in
solid
- Occurs through a convection current
- Radiation
- Radiation is the
process in which
thermal energy is
transferred by
electromagnetic waves.
It does not require a
medium, thus it can
occur in a vacuum
- Factors that affect rate of radiation
- Nature of the surface of the body; colour, reflectivity and texture. Surfaces
which are dark in colour, matte and rough are better radiators of heat compare
to surfaces which are light in colour, shiny and smooth