ass1: Wow create my first exam question part

superconductivity_assignment1_kvkempen.tex

@@ -110,7 +110,23 @@ Vanadium does, however, behave similar to the rest of the elements.
 In conclusion, the statement that superconductivity is more likely to be observed in metals whose normal state is highly resistive is rejected by this analysis of the superconducting elements.
 
 \section{Exam question electrodynamics in superconductors}
-No idea yet.
+In 1935, the London brothers established a first theory to explain the Meissner-Ochsenfeld effect.
+Although their theory was not completely correct, they derived two correct and important electrodynamical equations, which we know as the London equations.
+The first and second London equations are
+\[
+	\frac{\partial}{\partial t}(\Lambda \vec{J_s}) = \vec{E}
+	\qquad
+	\nabla \times (\Lambda \vec{J_s}) = \vec{B},
+\]
+with $\Lambda = \frac{m_e}{n_se^2}$, $m_e$ the normal electron mass, $n_s$ the superfluid electron density.
+
+\begin{enumerate}
+	\item \textbf{Describe the idea behind the London model for the Meissner-Ochsenfeld effect.}
+
+	\emph{The London model is based on the two fluid model that was proposed by Lev Landau a few years prior to the London model. The idea of the London model is the coexistence of two types of electrons in a superconductor, namely normal electrons and superelectrons. Both types can transfer electrical current, the normal electrons with resistance, the superelectrons without, and they do so in parallel. Heat can only be transferred by the normal electrons.\\\\ Electrons can change type. At high temperature, all the electrons are of the normal type. Below a critical temperature $T_c$, however, the density of superelectrons quickly emerges and a supercurrent can flow.}
+
+	\item ..
+\end{enumerate}
 
 \section{Difference between type-I and type-II superconductors}
 In the realm of conventional superconductors, we have type-I and type-II superconductors.