The ampullae of Lorenzini are special sensing organs termed electro-receptors, making long conductive jelly-filled canals on the heads of the sharks and rays. Such organs detect electric fields as weak as 500 nano-volts/m. Employ the Lorentz equation to illustrate that such electro-receptors can give the shark having a "compass-sense". Determine how fast does the shark encompass to swim perpendicular to the magnetic field of earth (B = 30 micro-teslas) in order to notice the magnetic field of earth with such organs?