# A problem concerning the force between currents or moving electrons

Concerning two identical wires carrying the same current (same direction, speed and magnitude), they will be attracted because of the Ampere force. But when I was in the frame moving with the same speed as the electron in the current, why will there be the same force between each wire (supposing that the electrons are moving at a speed far less than $c/10$).

Also, when two bundles of electrons are moving in the vacuum at the same speed, will they be attracted because of the Ampere force? Will they be dis-attracted because of the Coulomb force?

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Why would the force be different? Since the two wires are identical, what observed in the frame of an electron of one wire would be equally observed in the frame of an electron in the other wire. For the second question, I suppose both forces have to be taken into consideration. You can get the force by the Lorentz force $q(\mathbf{E} + \mathbf{v} \times \mathbf{B})$.