General relations with temperature
1. Resistivity
Note: Only isotropic materials are considered.
Note: Resistivity ρ (rho) is a linear function of
temperature.
The corresponding mathematical formula is:

ρ _{T}  Resistivity to be defined at a temperature T. Linear function of the temperature for an isotropic or anisotropic material. 
T _{REF}  Reference temperature. 
T  T is the temperature for which the resistivity must be computed. 
ρ _{REF}  Resistivity of the material at T _{REF} . 
a  Temperature coefficient at T _{REF} . 
2. Thermal conductivity for all materials except gas and liquid
The thermal conductivity is defined at a reference temperature and is considered as constant for all thermal computations.
The reference temperature is then only a memo, to keep in mind the temperature corresponding to the indicated thermal conductivity.
Symbol  Definition  Unit 
T _{ref}  Reference temperature (Tref)  °C 
K _{ref}  Isotropic thermal conductivity at Tref W/K/m)  W/K/m 
3. Specific heat variation versus temperature – For all material except gas and liquid
The specific heat is defined at a reference temperature and is considered as constant for all thermal computations.
The reference temperature is then only a memo, to keep in mind the temperature corresponding to the indicated specific heat.
Symbol  Definition  Unit 
T _{ref}  Reference temperature (Tref)  °C 
C _{ref}  Specific heat at Tref (J/K/Kg)  J/K/Kg 
4. Remanent induction of magnets
Note: Only isotropic magnet is considered.
Note: Remanent induction (Br) is a linear function of the
temperature.
The corresponding mathematical formula is:

Br _{T}  Remanent induction to be defined at a temperature T. Linear function of the temperature for an isotropic or anisotropic material. 
T _{ref}  Reference temperature. 
T  T is the temperature for which the remanent induction must be computed. 
Br _{ref}  Remanent induction of the magnet at T _{REF} . 
a  Reverse temperature coefficient for Br at T _{REF} . 
5. Intrinsic Coercivity
Note: Only isotropic magnet is considered.
Note: Intrinsic Coercivity (HcJ) is a linear function of the
temperature.
The corresponding mathematical formula is:

HcJ _{T}  Intrinsic Coercivity to be defined at a temperature T. Linear function of the temperature for an isotropic or anisotropic material. 
T _{ref}  Reference temperature. 
T  T is the magnet temperature for which the Intrinsic Coercivity must be computed. 
HcJ _{ref}  Intrinsic Coercivity of the magnet at T _{REF} . 
a  Reverse temperature coefficient for Hcj at T _{REF} . 