Question

What happens when two streams of electrons move parallel to each other in the same direction?

Answer 1

Electric repulsion:

1. Electric repulsion is basically a phenomenon that occurs when similar charges, such as two positive or negative charges, have been positioned near each other. Comparable charges repel each other while dissimilar charges attract, as per basic electrical rules of physics.
2. If indeed the beams remained stationary, they would repel each other (because negative charges repel). We always get magnetic effects when the beams move, which lessens the repulsion.
3. Mostly at c does the magnetic attraction becomes strong enough to offset the electric repulsion. As a result of electric repulsion, the streams would reject each other.

Therefore, when two streams of electrons move parallel to each other in the same direction, they will repel each other.