Two parallel wires carrying current in the same direction attract each other while two beams of electrons travelling in the same direction repel each other. Why?

Answer

A

Explanation

The current carrying wires are electrically neutral. Hence the only interaction between wires is of attractive magnetic force.
But in parallel beams of electrons both the beams have negative charge. Hence there is electrostatic repulsion and also magnetic attraction.Electrostatic repulsion has larger magnitude then magnetic attraction.Hence the beams repel.