current has a direction and magnitude, intuitively it should be a vector but my physics textbook describes it as a scalar. Why is that?
It is somewhat like the difference between speed and velocity. Current is defined to be the quantity of charge that flows past a point in a wire per unit time. In many cases the direction of the charge flow changes from one point to another, but the amount of charge passing a given point in a wire is the same at all points. There is a related vector quantity that you will encounter in the more advanced treatments of electricity and magnetism called the current density, usually designated by J. It appears in the differential form of Ampere's law. It is the charge per unit area per unit time in the direction of the charge flow. In a wire, the magnitude of the current density is I/A where A is the cross sectional area of the wire.quantumlight said:current has a direction and magnitude, intuitively it should be a vector but my physics textbook describes it as a scalar. Why is that?