Two point charges +Q each are placed at adjacent corners of a square. Other two point charges -Q each are placed at the remaining two corners of the same square . The side of the square is l. Find electric field intensity at the centre of the square.

Explanation

To find the electric field intensity at the center of the square with the given charges, we can follow these steps:

### Step 1: Understand the Configuration
We have a square with side length \( l \). At two adjacent corners, we have positive charges \( +Q \), and at the other two corners, we have negative charges \( -Q \).

### Step 2: Determine the Position of the Center
The center of the square is located at equal distances from all four corners. The distance from each corner to the center can be calculated using the Pythagorean theorem. The distance \( a \) from a corner to the center is given by:
\[
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