Basics Flashcards
Three modes of heat transfer
Conduction
Convection
Radiation
What is conduction
Heat flow only because of temperature gradient
No observable motion of matter
Metals flow of heat
Motion of free electrons
Convection
Observed by the movement of the fluid
Thermal conductivity vs heat transfer coefficient
Instrinsic property of substance vs combination of many things
Natural convection
Buoyancy forces created by density differences and density differences are caused by temperature gradient
Radiation
Transfer of energy through space in the form of electromagnetic waves
Radiation becomes important at high temperature and unaffected by flow
Conduction convection not affected by temperature it by flow mostly
Radiation
Radiation itself is not an energy or heat.
Heat is released when electromagnetic radiations which are pockets of photons carried by the waves strike an object
An ideal black body will absorb all the radiation which strikes it.
EM waves
They do not need to medium to propagate
However when they strike a object, they are transmitted reflected or absorbed
How are EM waves produced?
An oscillating charged particle will create an oscillation electric and magnetic wave
Radiation
May be by electric bombardment electric discharge and so on
Radiation
All materials above absolute zero emit radiation
