Transfer of thermal energy and its effect
The SI unit for temperature is kelvin(K)
Mode of transmission
Convection
Heat is transferred from one region of a fluid to another in a circulatory manner called a convection current.
The process of heat transfer through a medium by the movement of the particles in the medium
Takes place only in fluid.
A convection current is set up due to change in the density of the fluid
Radiation
Emitter
Absorber
Reflecter
The hotter the object is, the more heat energy it radiates.
The heat transfer by the emission of infrared radiation.
Good reflector: White, Shiny, Smooth
Poor reflector: Black, Rough
Poor emitter: White, Shiny, Smooth
Good emitter: Black, Rough
Good absorber: Black, Rough
Poor absorber: White, Shiny, Smooth
All objects can emit infrared radiation. Heat energy from infrared radiation is called radiant heat
The sun is the major source of radiant heat
Three things that affects radiation
Types of texture and colour of surface
Conduction
Cannot be in solid or vacuum
This mode of heat transfer does not require a medium, so it can take place in a vacuum
Radiation of hear moves in all direction
Heat energy from radiation is called radiant heat
Expansion
Contraction
Bimetallic strip
Conduction is the process of heat transfer through a medium without the movement of the particles in the medium
Poor conduction
Good conduction
The heating element in electric kettle is made of metal because it can conduct heat quickly to heat up water