Four positive point charges +q are kept at the four corners of a square of side l . The net electric field at the mid-point of any one side of the square is ( Take, 1 4 ₀ =k )

Step-by-step solution

The force at midpoint of any side of a square let's say at point P which is midpoint of side A B is due to charges at corners A, B, C and D F_P=F_ A P +F_ B P +F_ C P +F_ D P aligned & A P = D P =l & B P = C P = l^2+(l / 2)^2 = 5 l^2 / 4 aligned Electric field due to charges at A and D will be equal in magnitude and opposite in direction, so will cancel each other. Similarly, the vertical components of electric field due to charges at B and C will also cancel each other, but the horizontal components of these will