Hi Joe,
Electrical current seems to have a direction and magnitude. So is it a vector quantity?
Is current a vector?
Re: Is current a vector?
The normal convention for a current that stays in a quasi-one dimensional conductor such as a wire is
• treat the current as a scalar, which is conserved along the wire
• treat the local direction of the wire as a vector.
So, for instance, we write the magnetic force on a small section of wire dl carrying current i as
dF = i dl X B
Because of conservation of current, and the fact that the wire is usually bent, it's convenient to have i as a scalar, so it can have the same value around the circuit.
When we are not in a 1D conductor, then we need to use current density, to allow for variation in space. So in that case, the current density (symbol J ) is a vector.
Joe
• treat the current as a scalar, which is conserved along the wire
• treat the local direction of the wire as a vector.
So, for instance, we write the magnetic force on a small section of wire dl carrying current i as
dF = i dl X B
Because of conservation of current, and the fact that the wire is usually bent, it's convenient to have i as a scalar, so it can have the same value around the circuit.
When we are not in a 1D conductor, then we need to use current density, to allow for variation in space. So in that case, the current density (symbol J ) is a vector.
Joe