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Magnetic energy of solar flare

The problem reads as:
"The magnetic field permeating a region of space represents stored energy. This energy is often quantified in terms of its density (magnetic energy per unit volume) given by B^2/(2*u) where u=4*pi X 10^(-7). Suppose an "X2" flare occurs within a volume of 10^12 km3 over a sunspot pair initially permeated by an average magnetic field strength of 1000 Gauss. Calculate the total magnetic energy in Joules stored in the volume before the flare occurs. "

My dilemma.....I know that the given formula for magnetic pressure is a simplified version of the entire magnetic momentum flux relationship. But how can I use what is given? (a relationship in terms of density seems to continually yield a result of Newtons/meter2 which I understand to be magnetic pressure? I have resorted to blindly "plugging and chugging" in a an effort simply to get the right units. I assume that I should be able to take 1000 gauss over the given volume with the given mag pressure relationship and somehow attain an initial energy.

Thanks for any insight you might provide.

Solution Preview

We must express both B and the vacuum permeability ยต_0 in the same units - apparently SI, ...

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