Siemens (unit) plural. For a conducting element, electrical resistance "R" and electrical conductance "G" are defined as where "I" is the electric current through the object and "V" is the voltage (electrical potential difference) across the object. The unit siemens for the conductance "G" is defined by where Ω is the ohm, A is the ampere, and V is the volt. For a device with a conductance of one siemens, the electric current through the device will increase by one ampere for every increase of one volt of electric potential difference across the device. The conductance of a resistor with a resistance
Current density of the unit vectors. That is, the component of current density passing through the surface (i.e. normal to it) is , while the component of current density passing tangential to the area is , but there is "no" current density actually passing "through" the area in the tangential direction. The "only" component of current density passing normal to the area is the cosine component. Current density is important to the design of electrical and electronic systems. Circuit performance depends strongly upon the designed current level, and the current density then is determined by the dimensions of the conducting elements. For