ABC is an equilateral triangle of side 4.0 cm in a vacuum. There are point charges of 8.0C at A and B. Find (a) the potential, (b) the electric field at C.

Answer 1

potential is a scalar, you can add the potential from each point charge..
V=kq(1/d+1/d)

E is a vector, so you have to add as vectors. The are 60 degrees apart. Draw a sketch, you will see the resultant splitting the 60 degree angle, with the side componets adding to zero.

E=kqq (2/r^2 * cos30)