To understand the relationship between the electric potentials \( V_1 \) and \( V_2 \) at points \( P_1 \) and \( P_2 \) located along the axial line of a short dipole, we need to consider the nature of electric dipoles and how electric potential behaves in their vicinity.
Understanding Electric Dipoles
A short dipole consists of two equal and opposite charges, +q and -q, separated by a small distance, \( 2a \). The dipole moment \( \mathbf{p} \) is defined as \( \mathbf{p} = q \cdot 2a \) and points from the negative charge to the positive charge.
Electric Potential Due to a Dipole
The electric potential \( V \) at a point in space due to a dipole can be expressed as:
\( V = \frac{1}{4\pi \epsilon_0} \cdot \frac{\mathbf{p} \cdot \hat{r}}{r^2} \)
Here, \( \epsilon_0 \) is the permittivity of free space, \( \hat{r} \) is the unit vector in the direction from the dipole to the point where the potential is being calculated, and \( r \) is the distance from the dipole to that point.
Analyzing Points P1 and P2
In our scenario, points \( P_1 \) and \( P_2 \) are located at equal distances \( r \) from the center of the dipole, but on opposite sides. Therefore, we can denote their positions relative to the dipole moment:
- For point \( P_1 \): The potential \( V_1 \) is given by \( V_1 = \frac{1}{4\pi \epsilon_0} \cdot \frac{p}{r^2} \)
- For point \( P_2 \): The potential \( V_2 \) is given by \( V_2 = \frac{1}{4\pi \epsilon_0} \cdot \frac{-p}{r^2} \)
Establishing the Relationship
From the expressions for \( V_1 \) and \( V_2 \), we can see that:
\( V_1 = -V_2 \)
This indicates that the electric potential at point \( P_1 \) is equal in magnitude but opposite in sign to the potential at point \( P_2 \). This is a direct consequence of the dipole's symmetry and the nature of electric fields generated by dipoles.
Conclusion
In summary, for two points \( P_1 \) and \( P_2 \) located along the axial line of a short dipole and equidistant from its center, the relationship between their electric potentials is:
V1 = -V2
This relationship highlights the fundamental properties of electric dipoles and their influence on the surrounding electric field.