From 5a033eecad804081842c03ce92d62ecaa116ccbf Mon Sep 17 00:00:00 2001
From: Erik Strand <erik.strand@cba.mit.edu>
Date: Wed, 1 May 2019 00:25:24 -0400
Subject: [PATCH] Answer 13.4
---
_psets/10.md | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/_psets/10.md b/_psets/10.md
index 7ebf43c..3c5f4ec 100644
--- a/_psets/10.md
+++ b/_psets/10.md
@@ -144,6 +144,19 @@ This is reduced when $$H$$ and $$M$$ are anti-aligned.
{:.question}
Estimate the saturation magnetization for iron at 0 K.
+I looked up the density, molar mass, and number of valence electrons of iron. My answer also uses
+the proton mass and electron magnetic moment.
+
+$$
+\begin{align*}
+7,874 \si{kg/m^3}
+&\cdot \frac{1 \text{ nucleon}}{\num{1.67e-27} \si{kg}}
+\cdot \frac{1 \text{ atom}}{55.845 \text{ nucleons}} \\
+&\cdot \frac{2 \text{ electrons}}{1 \text{ atom}}
+\cdot \frac{\num{9.28e-24} \si{J/T}}{1 \text{ electron}} \\
+&= \num{1.6e6} \si{A/m}
+\end{align*}
+$$
## (13.5)
--
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