Update docs/3_drude_model_solutions.md

docs/3_drude_model_solutions.md

@@ -15,9 +15,7 @@ search:
     so it does not depend on the sample geometry.
 
 
-2. If the hall resistance and the magnetic field are known, we extract the charge density using $R_{xy} = -\frac{B}{ne}$.
-
-  As $V_x = -\frac{I_x}{ne}B$, a stronger field yields a larger Hall voltage, making it easier to measure. Likewise, a lower charge density yields a larger Hall voltage, making it easier to measure.
+2. If the hall resistance and the magnetic field are known, we extract the charge density using $R_{xy} = -\frac{B}{ne}$. As $V_x = -\frac{I_x}{ne}B$, a stronger field yields a larger Hall voltage, making it easier to measure. Likewise, a lower charge density yields a larger Hall voltage, making it easier to measure.
 
 3. The resistance is
 
@@ -47,7 +45,7 @@ See 3_drude_model.md
 
 1. $\rho_{xx}$ is independent of B and $\rho_{xy} \propto B$
 
-2. 
+2. The conductivities are 
     $$
     \sigma_{xx} = \frac{\rho_{xx}}{\rho_{xx}^2 + \rho_{xy}^2} = \frac{mne^2\tau}{m^2+e^2\tau^2 B^2}
     $$
@@ -59,7 +57,7 @@ See 3_drude_model.md
 3. This describes a [Lorentzian](https://en.wikipedia.org/wiki/Spectral_line_shape#Lorentzian).
 
 
-4. see lecture notes. The sign of the hall coefficient indicates the dominant charge carriers.
+4. see lecture notes. The sign of the hall coefficient depends on sign of the charge carrier (as analyzed in the next exercise).
 
 
 ### Exercise 4. Positve and negative charge carriers
@@ -75,7 +73,7 @@ See 3_drude_model.md
 
 4. The net current in the y-direction should be zero.
 
-5. 
+5. The Hall coefficient is
 
     $$
     R_H = \frac{n_h\mu_h^2 - n_e\mu_e^2}{e(n_h\mu_h + n_e \mu_e)^2}