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Question

# Electric current has both magnitude and direction . But still ,it is referred to as a scalar quantity. I mean,how's that possible??!!

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Solution

## When we bend a current carrying wire, the current remains within the wire and changes direction along with wire. The concept of direction is different here compared with all vector quantities. Direction of current in DC is from positive terminal to negative terminal, and if there is a wet surface, there will be a tracking current along this wey surface over insulation , irrespective of physical shape of the track. The only condition is it will flow from higher potential to lower one. Current in AC is totally different , where direction of flow of charges cannot be defined in the normal explanation. Electrons are not even moving physically in a defined direction, and still it is a current. Consider a vacuum tube, where free electrons are at hot cathode region get attracted to positive anode. At cathode they are distributed over an area of cathode. Anode is a small area in comparison. So electrons from a wide area are travelling to a small anode. Direction of electron flow is different from different parts of cathode region, though all travel to the same positive electrode. If we have a conducting ionic liquid, with two rod terminals dipped in it, currents will flow through all the liquid, and it will be composed of several paths of ions in different parts of liquid, joining/ concentrating on these two poles. There is no part of liquid without flow charge. So direction carries no meaning here in normal sense. Since the very premise of accepted definition of direction of vector does not hold, and current is thus a scalar quantity.

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