Methods of Thermal EnergyTransfer Flashcards
What is conduction
conduction occurs when two objects of different temperatures are in direct contact
heat is transferred from one particle to another when those particles collide.
solid>liquid>gas due to particles being close
what is natural convection
natural convection describes the motion of a fluid that is caused by natural forces within it.
what is the most common natural convection
buoyancy - hotter parts of the fluid are less dense so they float upwards
as the fluid flows around, it forms a convection current which carries thermal energy throughout the fluid.
What is forced convection
describes the motion of a fluid that is caused by forces outside of it
these forces often move the fluid faster than or in a different direction to natural convection
examples of forced convection
fans in your house, your oven, computer
what is radiation
consists of electromagnetic waves which transmit energy from a source to an absorber
this is the only form of heat transfer that does not involve the movement of particles.
higher the temperature of the emitter, the greater the amount of radiation.
can objects absorb and radiate electromagnetic waves at the same time
yes
how do objects with higher tempeatures radiate
radiate more energy than they absorb so they cool down
how do objects with lower tempeatures radiate
absorb more energy than they radiate so they warm up
how does a smooth surface radiate
they dont radiate much or absorb much, rough surfaces do
how does a reflective or white surface radiate
they don’t radiate or absorb heat much, dark and black surfaces do.
what are conductors
a thermal conductor is any material through which thermal energy flows quickly
copper and iron are good thermal conductors
what are insulators
a thermal insulator is any material through which thermal energy flows slowly
most non metallic materials are good thermal insulators
