# Magnet (unidirectional): linear approximation, linear function of T

## Presentation

This model defines remanent flux density (Br) as a linear function of the temperature for a magnet with an isotropic permeability.

## Mathematical model

Remanent flux density is a linear function of the temperature.

The corresponding mathematical formula is written:

B_{r}(T) = Br_{ref} * (1 + a * (T - T_{ref} ))

where:

- T ref is the reference temperature degree or Kelvin
- B
_{r}ref is the remanent induction of the magnet at T_{ref}Tesla - a is a reverse temperature coefficient for the remanent induction Br
(degree
^{-1})

The shape of Br (T) curve is presented in the figure below.