Derive a relation for electric field of an electric dipole at a point on its equitorial line.

Explanation

To derive the relation for the electric field of an electric dipole at a point on its equatorial line, we can follow these steps:

### Step 1: Understand the Configuration of the Dipole
An electric dipole consists of two equal and opposite charges, +Q and -Q, separated by a distance \( l \). The point where we want to calculate the electric field is located on the equatorial line, which is the perpendicular bisector of the dipole.

### Step 2: Set Up the Diagram
Draw a diagram with the dipole positioned along the x-axis. Let the positive charge (+Q) be at point \( A \) and the negative charge (-Q) be at point \( B \). The distance from the midpoint of the dipole to the point \( P \) on the equatorial line is \( r \).

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