Energy transfer mechanisms Convection Energy is transferred by flow of substance E.g.: heating a room (air convection E.g. warming of North Altantic by warm waters from the equatorial regions Natural convection from differences in density Forced convection from pump of fan p Radiation: Energy is transferred by photons E.g.: infrared lamps Stephans law fo oAe T4: Power o=5.7x10-8 W/m2 K4 t is in Kelvin and a is the surface area e is a constant called the emissivity Physics 121: Lecture 25, Pg 9Physics 121: Lecture 25, Pg 9 Energy transfer mechanisms Convection: Energy is transferred by flow of substance E.g. : heating a room (air convection) E.g. : warming of North Altantic by warm waters from the equatorial regions Natural convection: from differences in density Forced convection: from pump of fan Radiation: Energy is transferred by photons E.g. : infrared lamps Stephan’s law s = 5.710-8 W/m2 K4 , T is in Kelvin, and A is the surface area e is a constant called the emissivity  = sAe T4 : Power