Merge branch 'master' into local

src/1_einstein_model.md

@@ -344,8 +344,9 @@ ax.set_ylim((0, 3));
 
 1. Sketch the Bose Einstein distribution as a function of $\omega$ for two different values of $T$
 2. Sketch the heat capacity of an Einstein solid for two different values of $T_E$
-3. What is the high-temperature heat capacity of an atom is a solid with two momentum and two spatial coordinate degrees of freedom
+3. What is the high-temperature heat capacity of an atom in a solid with two momentum and two spatial coordinate degrees of freedom?
 4. Why is the heat capacity per atom of an ideal gas typically $3k_B/2$ and not $3 k_B$?
+5. Explain which behaviour of the function $1/(e^{-\hbar\omega/k_BT}-1)$ tells you it is not the Bose Einstein distribution.  
 
 ### Exercise 1: Heat capacity of a classical oscillator.