StevenJacobs990
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Is the direction of electric field save as the direction of (conventional) current?
The direction of the electric field is not the same as the direction of conventional current in general. The electric field drives the motion of electrons, which flow opposite to the direction of the electric field. However, in conductive materials, the direction of the current and the electric field align and are proportional, as described by Ohm's Law. Special cases, such as anisotropic materials like graphite, demonstrate that current density may not always align with the electric field direction.
PREREQUISITESStudents in high school physics, electrical engineers, and anyone interested in understanding the relationship between electric fields and current flow in various materials.
StevenJacobs990 said:Is the direction of electric field save as the direction of (conventional) current?
@davenn is correct. In general the electric field and the current are not in the same direction.StevenJacobs990 said:Is the direction of electric field save as the direction of (conventional) current?
Careful here. Th direction of Positive charge is defined by the direction of the field. That is the direction of the conventional current. Signs need to be observed meticulously and that post doesn't make it as clear as it should. Anyone who is struggling will need to make a conscious effort to realize minus times minus is plus when doing the sums.davenn said:no, it's in the direction of charge flow ... electron direction. It is the electric field that drives the motion of the electrons/charge
I would say that is perfectly correct and that bringing electrons in is not relevant here. The sign of the particles carrying the current is something that comes in much later.StevenJacobs990 said:Is the direction of electric field same as the direction of (conventional) current?
I don't get this. Positive charges will flow from a positive plate to a negative plate. That is also direction of the Field, isn't it? It may be that electrons are carrying the charge but that doesn't affect the conventional current.Dale said:@davenn is correct. In general the electric field and the current are not in the same direction.
However, in the special case of a current inside a conductive material the direction of the current and the direction of the E field are the same and they are proportional to each other. This is the meaning of Ohm's law
I was thinking of free charges in vacuum, where you can have currents (charge velocity) without an E field (charge acceleration).sophiecentaur said:Did you have something else in mind?
That's a relief!Dale said:I was thinking of free charges in vacuum, where you can have currents (charge velocity) without an E field (charge acceleration).
Yes. It's a scientific truth but does it help with the OP's question? Seasoned PF members don't always take not of the Code Letter, associated with the title. It's a B, in this case, meaning basic High School Level.jtbell said:There are anisotropic materials (e.g. graphite) in which the resistivity is described by a tensor, and the current density at a point is not necessarily in the same direction as the electric field.
https://en.wikipedia.org/wiki/Elect...ty#Tensor_equations_for_anisotropic_materials
This is a rather advanced topic, though. I don't remember seeing it in an introductory textbook.