Lag1989 task №12.34

Find the repulsive force (per unit length) F1 of two identically charged infinitely long parallel threads with the same linear charge density of 3 μC / m, which are in vacuum at a distance b = 2 cm from each other. Find the same work (per unit length) A1 that you need to accomplish in order to bring these threads closer to a distance of a = 1 cm.