Thermal Equibirium

·         If no heat flows between then when they are connected by a path permeable to heat.

·         Zeroth Law of thermodynamics.

·         Temporally uniform.

·         System allows transfer of energy as heat but does not allow transfer of matter or transfer of energy as work.

·         Heat can flow in to or out of a closed system by away of thermal condition or of thermal radiation to or from a thermal reservoir.