Determine the differences in potential vbavb-va vcb vc-vb

Question

A uniform electric field E =-3.4N/Ci points in the negative x direction as shown in the figure. The x and y coordinates of points A, B, and C are given on the diagram (in meters). 

A at (4,1), B at (4,4) and C at (-3,4).

Determine the differences in potential V_BA=V_B-V_A, V_CB =V_C-V_B, and V_CA=V_C-V_A

A thin cylindrical shell of radius R₁=6.5cm is surrounded by a second cylindrical shell of radius R₂=8.7cm, as in the figure . Both cylinders are 12 m long and the inner one carries a total charge Q₁=-0.87μC and the outer one Q₂=+1.47μC

For points far from the ends of the cylinders, determine the magnitude of the electric field at a radial distance r from the central axis of 7.0 cm

 For points far from the ends of the cylinders, determine the magnitude of the electric field at a radial distance r from the central axis of 13.2 cm