Electric Dipole Moment Calculator

• Two-charge dipole: p = q d, direction from −q to +q.
• Multiple charges: p = Σ qᵢ rᵢ relative to your chosen origin.
• Uniform polarization: p = P V for constant polarization.
• Optional: τ = p × E, U = −p · E.

1. Select a model that matches your setup.
2. Enter values and choose correct units.
3. Provide direction only when you need it.
4. Click Calculate to view results above.
5. Use export buttons to download your results.

Electric dipole moment in practice

Electric dipole moment summarizes separated charge in a compact vector. It is central in molecular physics, dielectric materials, and sensing. This calculator supports three common models and consistent unit handling. Results appear in C·m and also in Debye for molecular comparisons.

Units and scale conversions

One Debye equals 3.33564×10⁻³⁰ C·m, which is tiny. A 1 e charge separated by 1 Å produces about 4.80 D. That is why angstroms and electron charge appear often in chemistry. For macroscopic charges, Debye values become extremely large.

Two-charge dipole model behavior

For a classic dipole, p = q d points from −q to +q. If q = 2 μC and d = 3 cm, |p| = 6×10⁻⁸ C·m. Direction only changes the vector components, not the magnitude. Use the optional direction vector for arbitrary orientations.

Multiple charge distributions

For several point charges, p = Σ q_i r_i depends on the chosen origin. A neutral pair, +5 nC at +1 cm and −5 nC at −1 cm, yields |p| = 1×10⁻¹² C·m along the x axis. Shifting the origin changes p for non‑neutral totals.

Polarization and bulk materials

In dielectrics, polarization P describes dipole density per area. With uniform P, the total moment is p = P V. For example, P = 2 μC/m² across 500 cm³ gives 1×10⁻⁹ C·m. This links microscopic alignment to measurable macroscopic response.

Torque in an electric field

When an external field exists, a dipole experiences torque τ = p × E. Torque magnitude is |τ| = |p||E|sinθ, maximizing at 90 degrees. Enter Ex, Ey, Ez to compute vector torque in N·m. This is useful for alignment and rotational dynamics estimates.

Potential energy and alignment

Dipole potential energy is U = −p · E. The energy becomes more negative as p aligns with E. For small dipoles in strong fields, energy differences can influence orientation. This calculator reports U in joules whenever field components are provided.

Typical reference values

Many polar molecules have moments near 1–5 D. Water is about 1.85 D, hydrogen chloride about 1.08 D, and ammonia about 1.47 D under common conditions. Comparing your computed Debye output with such values aids sanity checks.

1) What direction does the dipole vector point?

The dipole moment points from the negative charge toward the positive charge. In the two‑charge model, this direction is enforced. For the multi‑charge model, the direction follows the vector sum Σqᵢrᵢ.

2) Why does the multi‑charge result depend on the origin?

Because p = Σqᵢrᵢ uses position vectors from your chosen origin. If the net charge is nonzero, shifting the origin changes the computed moment. For neutral systems, differences are much smaller and often cancel.

3) When should I use the polarization model?

Use it for bulk materials with approximately uniform polarization, such as a slab dielectric under a steady field. If you know P in C/m² and volume V, then p = P·V gives the total dipole moment.

4) What is a realistic Debye value?

Molecular dipole moments are often a few Debye, typically 1–5 D. If you enter microcoulombs and centimeters, the Debye output can be astronomically large. That is normal for macroscopic charge separations.

5) How are torque and energy computed?

If you enter field components, the calculator computes τ = p × E and U = −p · E using SI units. Torque is reported in N·m and energy in joules. Leave E blank to skip these quantities.

6) Can I enter negative charges?

Yes, in the multiple‑charge table you may enter positive or negative values. In the two‑charge model, q is treated as a magnitude because the dipole is defined by ±q separated by distance d.

7) What should I do if results look incorrect?

Check unit selections first, then confirm distance and charge magnitudes. For vectors, verify direction entries are nonzero. In the multi‑charge model, ensure each used row has q, x, y, and z filled completely.