Talk:Magnetic helicity

d³

in the equation, what do the quantities d³ and r mean?

$H=\int {\mathbf {A} }\cdot {\mathbf {B} }\,d^{3}{\mathbf {r} }$

-- 99.231.208.23 (talk) 23:37, 10 July 2008 (UTC)

They refer to a volume integral. "dr" indicates a unit of length, and $d^{3}{\mathbf {r} }$ is three of these together; a unit of volume. It may be that the physics you are reading might be too advanced for you at the moment. 82.16.99.131 (talk) 13:26, 30 September 2008 (UTC)

"Magnetic helicity is a conserved quantity. It is conserved in electromagnetic fields, even when magnetic reconnection dissipates energy. The concept is useful in solar dynamics and in hydromagnetic dynamo theory." Well this is very interesting. Not only do we have conservation of energy, conservation of momentum, and conservation of angular momentum, we apparently have conservation of magnetic helicity as well! So it interests me what the SI unit of magnetic helicity is.

$\mathbf {A}$ Vector potential

volt-seconds / meter

$\mathbf {B}$ Magnetic field

newton-seconds / coulomb-meter

or

volt-seconds / meter^2

$d^{3}{\mathbf {r} }$ Differential volume element

The SI unit for magnetic helicity would therefore be Webers^2.

Kmarinas86 (Expert Sectioneer of Wikipedia) ^{19+9+14 + karma = 19+9+14 + talk = 86} 14:35, 7 December 2010 (UTC)

History of subject

When was it discovered? Infovarius (talk) 11:46, 3 November 2009 (UTC)

Conserved quantity

Article says "It is a conserved quantity in electromagnetic fields," It is an integral over volume, so is it conserved in each/any volume or only if you integrate over the whole universe ? A simple example/calculation might help ? If it is conserved how is it created ? - Rod57 (talk) 16:27, 1 February 2016 (UTC)