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The electric field on the **axis of a dipole** (dipole moment p, distance r from centre, r >> a) is given by:
AE = kp/r³ (perpendicular to axis)
BE = 2kp/r³ (along the dipole axis, from −q to +q)
CE = kp²/r³
DE = kp/(r² + a²)
Answer & Solution
Correct answer: B. E = 2kp/r³ (along the dipole axis, from −q to +q)
**Axial dipole field**: E_axial = **2kp/r³** (along p direction). **Equatorial dipole field**: E_eq = **−kp/r³** (opposite to p). At large r, **axial is exactly twice the equatorial magnitude**, both decay as 1/r³ (faster than 1/r² for a point charge).
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