# Split the difference

**Electricity and Magnetism**Level 2

When \(\displaystyle T\) crosses \(T_c\), however, there is a qualitative shift in the allowed values of \(m^*\), and the system undergoes a phase transition.

Suppose we're working with the system at a temperature \(\displaystyle T\) below \(T_c\) such that \(T-T_c=-10\), find \(\lvert m^*\rvert\).

**Assumptions**

- The system always resides in states \(m^*\) which minimize its free energy. These are the "physical" states of the system.