PHYSICS · Multi-part · CBSE · Physics · Electric Charges and Fields · Electric Charges and Fields
Problem
Four identical point charges, each of magnitude +q, are fixed at the corners of a square of side length a that lies in the plane of the page. No other charges are present.
Respond to the prompts below. Explanations should be rooted in the properties of electric-field lines and the symmetry of the arrangement.
(a) Sketch a minimal but representative set of electric-field lines for this configuration, showing clearly any symmetry you employ and indicating arrow directions.
(b) Determine the direction of the net electric field at the geometric center of the square and justify your answer without performing any explicit vector calculations.
(c) Compare the electric-field magnitudes at the midpoint of a side and at a corner of the square. Provide a qualitative ranking and support it with reference to the spatial distribution of field lines.
(d) Suppose the charge at the upper-right corner is replaced with an equal-magnitude negative charge. Describe qualitatively how the overall electric-field line pattern and the field at the center would change.