Three point charges 1pC each are kept at the vertices of an equilateral triangle of side 10 cm. Find the net electric field at the centroid of the triangle.
Answer: Zero.
Solution
The centroid is equidistant from the three equal charges. Each charge produces a field of the same magnitude at the centroid, directed along the line from that vertex through the centroid. The three fields are equal in magnitude and mutually at 120∘, so their vector sum is zero. Hence the net field at the centroid is zero.
