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Commit 4ba91548 authored by Erik Strand's avatar Erik Strand
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Fix relative URL issue

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......@@ -179,10 +179,10 @@ coercivity of iron is $$\num{4e3} \si{A/m}$$.
Approximately what current would be required in a straight wire to be able to erase a $$\gamma
\text{-} Fe_2 O_3$$ recording at a distance of 1 cm?
As found in problem 6.4 in [problem set 4](/psets/04.html), the magnitude of the magnetic field a
distance $$r$$ away from an infinitely long and thin conductor carrying a current $$I$$ is $$I/(2
\pi r)$$. To erase information stored on $$Fe_2 O_3$$ we need this field to be about as strong as
the coercivity $$H_C = 300 \si{Oe}$$. Thus the current needed is
As found in problem 6.4 in [problem set 4](04.html), the magnitude of the magnetic field a distance
$$r$$ away from an infinitely long and thin conductor carrying a current $$I$$ is $$I/(2 \pi r)$$.
To erase information stored on $$Fe_2 O_3$$ we need this field to be about as strong as the
coercivity $$H_C = 300 \si{Oe}$$. Thus the current needed is
$$
\begin{align*}
......
......@@ -25,11 +25,11 @@ determine the current, relate the measurement to fundamental constant(s).
If a SQUID with an area of $$A = 1 cm^2$$ can detect 1 flux quantum, how far away can it sense the
field from a wire carrying 1 A?
As found in problem 6.4 in [problem set 4](/psets/04.html), the magnitude of the magnetic field a
distance $$r$$ away from an infinitely long and thin conductor carrying a current $$I$$ is $$I/(2
\pi r)$$. One flux quantum is $$\num{2.07e-7} \si{G \cdot cm^2}$$ i.e. $$\num{2.07e-11} \si{T \cdot
cm^2}$$. So to get one flux quantum over $$1 \si{cm^2}$$, we need a magnetic field of
$$\num{2.07e-11} \si{T}$$. Thus a one amp current can be detected at a distance of
As found in problem 6.4 in [problem set 4](04.html), the magnitude of the magnetic field a distance
$$r$$ away from an infinitely long and thin conductor carrying a current $$I$$ is $$I/(2 \pi r)$$.
One flux quantum is $$\num{2.07e-7} \si{G \cdot cm^2}$$ i.e. $$\num{2.07e-11} \si{T \cdot cm^2}$$.
So to get one flux quantum over $$1 \si{cm^2}$$, we need a magnetic field of $$\num{2.07e-11}
\si{T}$$. Thus a one amp current can be detected at a distance of
$$
\begin{align*}
......
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