Electrons move from higher potentials to lower potentials, which means it has a direction and can be referred to as a vector. Many textbooks, however, mention that current is a scalar. Can anyone clarify this for me?

I agree as well. For the current density it can be said that this is clearely a vector. The best example can be derived from plasma physics where the current density is the vector sum of the single plasma species current density vectors as it id the case e.g. in an plasma arc. These densities by the way are directly proportional to the species' velocity vector. In literature this can easily traced by having a look at Ohm's Law for plasmas which is a vector equation.

Jan 18, 2013

All Answers (13)

Pankaj Singh · Indian Institute of Technology Kanpur

current doesn't follow vector addition and decomposition law,so it is not a vector.Current density is a vector quantity.

Jan 15, 2013

Issam Sinjab · Alumni University of Leicester & University of Sussex

The direction you are referring to is essentially a consequence to the potential difference of the electrodes and is similar to stating that an object with some gravitational potential energy that "falls" with kinetic energy is a vector quantity, which we know is not. But its velocity is. Just to expand on electric current, steady state of charge flow through a given surface is I = Q/t where a more general representation is the rate at which charge passes through a surface expressed as i = dQ/dt in differential form. Hope that helps.

When you specify current, the positive or negative sign takes care of the direction and only a quantitative value is derived, if you draw a circuit diagram. Hence, it is a scalar quantity, whereas rate of current flow di/dt will be a vector.

I think that Daniel's and Pankaj's answers are correct. However, the current (as a scalar) is often associated (multiplied) with the direction vector because the EM field associated to the current depends on the direction as well as on maginude and phase of the current.

I agree as well. For the current density it can be said that this is clearely a vector. The best example can be derived from plasma physics where the current density is the vector sum of the single plasma species current density vectors as it id the case e.g. in an plasma arc. These densities by the way are directly proportional to the species' velocity vector. In literature this can easily traced by having a look at Ohm's Law for plasmas which is a vector equation.

As Pankaj and Daniel point out, the current density is indeed a vector quantity. The current is the integral of the current density passing through a specified surface. The surface might be the cross-section of a wire, for example. A key point is that the normal vector to the surface is defined to point in a specific direction, and the integrand is the scalar product (dot product) of the current density and the local normal. The sign of this dot product distinguishes "positive" current from "negative". The current, therefore, is a scalar with a sign.

Jan 22, 2013

Pathiyil Hithes · Sreepathy Institute of Management And Technology

Current has some direction so we might think that current is a vector, but it is not. Electric current I=q/t, here q=ne according to law of quantisation of charge here both 'n' and 'q' are scalars same is the case with 't'. so current is a scalar in form. In kirchoff's current law we add and subtract current based on a point considered. If the current is approching a junction it is considered as positive and when it leaves the junction it is considered as positive. Again here also we consider current as a scalar

Apr 16, 2013

Pathiyil Hithes · Sreepathy Institute of Management And Technology

Electric current density is vecator because j=i/a here a is area its a vector quantity

Please, I am a bit confused in what is going on here about current. We all know that current is directional but thinking about it as a vector, it doesn't obey the laws of vector addition considering angular change... now considering it also as a scalar, what will become of the direction usually assigned to it?

Apr 16, 2013

Antonio Pérez-Quintana · Center for Research and Advanced Studies of the National Polytechnic Institute

There is a difference between the current and the current density. The current density describes the quantity of charge flowing (charge per unit time) per unit area, and it is a 3-vector. You integrate the current density which passes through a surface and then you get the (total) current, and the sign depends on the direction of the current density and the vector surface differential \vector(dS) you have taken to do the integral.

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Pankaj Singh· Indian Institute of Technology KanpurGeorg Herdrich· Universität Stuttgart## All Answers (13)

Pankaj Singh· Indian Institute of Technology KanpurIssam Sinjab· Alumni University of Leicester & University of SussexFor a good illustration of this see the reference below:

http://www.physicshandbook.com/topic/topice/elec-cur-scalar.htm

Daniel Schaeffer· University of UtahVaidehi Venkatakrishnan· AAPMZoran Blazevic· University of SplitGeorg Herdrich· Universität StuttgartDavid G Grier· New York UniversityPathiyil Hithes· Sreepathy Institute of Management And TechnologyPathiyil Hithes· Sreepathy Institute of Management And TechnologyJohn Wisdom O.· Abia State Polytechnic, AbaAntonio Pérez-Quintana· Center for Research and Advanced Studies of the National Polytechnic InstituteCan you help by adding an answer?