Three 10-cm-long rods form an equilateral triangle. Two of the rods are charged to + 19 nC, the third to - 19 nC. What is the electric field strength at the center of the triangle?

We calculate the electric field as follows:

r = √ (3) / 6 x 19 cm =.05484 m

The angle for the triangle would be 30 on each side.

tan (30) = r / (L/2)

E' = kQ/{r*sqrt[ (L/2) ^2 + r^2]} = (8.99e9 x 15e-9) / {.05484 * sqrt[ (.19/2) ^2 +.003]}

E' = 22413 N/C

The value above is the electric field strength for a single rod at the center.

|E'| = 22413 N/C

E = 2|E'|sin (30) + |E'| = 49000 N/C