Magnetometer Carl Friedrich Gauss, head of the Geomagnetic Observatory in Göttingen, published a paper on measurement of the Earth's magnetic field. It described a new instrument that consisted of a permanent bar magnet suspended horizontally from a gold fibre. The difference in the oscillations when the bar was magnetised and when it was demagnetised allowed Gauss to calculate an absolute value for the strength of the Earth's magnetic field. The gauss, the CGS unit of magnetic flux density was named in his honour, defined as one maxwell per square centimeter; it equals 1×10 tesla (the SI unit). Francis Ronalds and Charles
Flux quantum state ψ(r, t) have a probability density defined as So the probability of finding a particle in a differential volume element dr is Then the number of particles passing perpendicularly through unit area of a cross-section per unit time is the probability flux; This is sometimes referred to as the probability current or current density, or probability flux density. As a mathematical concept, flux is represented by the surface integral of a vector field, where F is a vector field, and d"A" is the vector area of the surface "A", directed as the surface normal.For the second,n is the