Physics · Electrostatic Potential

Consider an electric dipole of dipole moment \( p \). At a large distance \( r \), the electrostatic potential at an angle \( \theta \) with the dipole axis is given by \( V = \frac{1}{4\pi\varepsilon_0} \frac{p \cos\theta}{r^2} \). What is the potential on the axial line of the dipole where \( \theta = 0^\circ \)?

1. A
   \( \frac{p}{4\pi\varepsilon_0 r^2} \)
2. B
   \( -\frac{p}{4\pi\varepsilon_0 r^2} \)
3. C
   Zero
4. D
   \( \frac{p}{4\pi\varepsilon_0 r} \)