Question

Electric field due to a dipole at a equatorial point depends upon r-n . Value of n is

Answer 1

Given:
Electric field due to an electric dipole at an equatorial point

Step 1: Concept of electric dipole
An electric dipole consists of two equal and opposite charges separated by a small distance.
Dipole moment = p = q × 2a

Step 2: Electric field at equatorial point
At equatorial position, the net electric field is given by:
E = (1 / 4πϵ₀) × (p / r³)

Step 3: Dependency on distance
From the formula,
E ∝ 1 / r³

Step 4: Compare with given form
E ∝ r⁻ⁿ
⇒ n = 3

Step 5: Physical meaning
Electric field due to dipole decreases very rapidly with distance compared to a single charge (which follows 1/r²).

Final Answer: 3