Identical point charges are placed on the vertices of a regular octagon of…
PHYSICS · Subjective · CBSE · Physics · Electric Charges and Fields · Electric Charges and Fields
Problem
Identical point charges are placed on the vertices of a regular octagon of circumradius R as follows:
• successive vertices carry charges +Q, −Q, +Q, −Q, and so on (i.e. adjacent vertices always have opposite signs).
Let O be the centre of the octagon.
(i) Prove that the net electric field at O is zero.
(ii) Suppose instead that the first four consecutive vertices carry +Q each and the remaining four consecutive vertices carry −Q each. Determine the magnitude and direction of the electric field at O in this case.