Electric Dipole moment is the measure of the polarity of the system. It is the separation of positive charge and a negative charge by a distance. The **SI unit** **of electric dipole moment is** **Coulomb-meter**. The simplest example is a pair electric charge of two opposite sign and equal magnitude separated by distance.

## What is Electric Dipole?

Suppose there are two charges of equal magnitude â€˜qâ€™, separated by a distance â€˜dâ€™. Let the first charge be negative and the second charge be positive. This combination can be called as an **electric dipole**. Therefore, we can say that an electric dipole is created by the combination of equal and opposite charges by a separation of a certain distance.

Now, the electric dipole moment for this pair of equal and opposite charges is equal to the magnitude of the charges multiplied by the distance between them.

### Magnitude of Electric Dipole Moment

The magnitude of electric dipole moment can be written as:

## Direction of Electric Dipole Moment

**You may also want to check out these topics given below!**

- Electric Potential Of A Dipole And System Of Charges
- Torque on an Electric Dipole in an Uniform Electric Field
- Magnetic Dipole Moment

### Electric potential due to a Dipole (V)

Suppose there are two charges â€“q, placed at A, and +q placed a B, separated by a distance d, forming a dipole. Suppose the midpoint of AB is O.

*The Electric potential due to a dipole at any point P, such that OP = r will be:*

V = \(\frac{1}{4\pi \epsilon } \frac{p cos \theta }{r^{2}}\) |

**Case 1:** If Î¸ = 90Â°

Electric potential = V = 0Â |

**Case 2:** If Î¸ = 0Â°

Electric potential = V = \(\frac{1}{4\pi \epsilon } \frac{p }{r^{2}}\)Â |

### Electric Dipole Questions

**Q1) Define electric dipole.**

**Answer:**

An electric dipole is the measure of a systemâ€™s overall polarity. It is defined as the measure of positive and negative electrical charges within a system.

**Q2) Which of the following is true of an electric dipole.**

**A pair of equal and unlike charges separated by a small distance****A pair of unequal and like charges located at the origin****A pair of equal and like charges located at the origin****A pair of unequal and unlike charges separated by a small distance**

**Answer: **a. A pair of equal and unlike charges separated by a small distance

An electric dipole is a pair of equal and unlike charges separated by a small distance.

**Q3) Find the potential due to the dipole when the angle subtended by the two charges at the point P is perpendicular.**

**Answer: **The potential due to the dipole when the angle subtended by the two charges at the point P is perpendicular is zero.

The potential due to a dipole is given by the formula V = m cos Î¸/(4Ï€Îµr^{2}). When the angle is perpendicular Î¸ = 90, therefore cos 90 = 0 as result of which the potential is zero.

**Q4) Dipole moments are used to calculate the _____.**

**susceptibility****electric field intensity****strength of the dipole in the field****polarisation patterns**

**Answer: **d. polarisation pattern

Dipole moments are used to calculate the polarisation pattern.

**Q5) Calculate the distance between two charges of 6 C with a dipole moment of 8 units.**

**Answer:**

The dipole moment of a pair of charges is given by the formula

M = Q x d

Rearranging the formula, we get

d = M/Q

Substituting the values in the above equation, we get

d = 8/6 = 1.33 units

**Q6) Calculate the dipole moment of equal charges of 7C separated by a distance of 4 cm.**

**Answer:**

The dipole moment of charge can be calculated as follows:

M = Q x d

Substituting the values, we get

M = 7 x 0.04 = 0.28 C-m

The dipole moment of the given pair of charge is 0.28 C-m.

**Q7) Dipole under the influence of an electric field will undergo _____.**

**Polarisation****Electromagnetism****Magnetisation****Magnetism**

**Answer**: a.polarisation

Dipole under the influence of an electric field will undergo polarisation.

**Q8) The electric potential due to a dipole is given by the formula _____.**

**Answer:**

The electric potential due to a dipole is given by the formula \(V=\frac{1}{4\pi \varepsilon }\frac{p\cos \Theta}{r^2}\).

**Q9: What is the net force acting on a dipole placed in a uniform electric field?**

**Ans: **The forces on the two charges constituting dipole are equal and opposite. Hence the net force is zero.

**Q10: What is the SI unit of dipole moment?**

**Ans:** The SI unit of dipole moment is Coulomb.meter

**Q11: Define the dipole axis of a dipole.**

**Ans: **The line passing through the two opposite charges of a dipole is called dipole axis

**Q12: Define the equatorial axis of a dipole?**

**Ans:** The line passing through the centre of the dipole axis and perpendicular to the dipole axis is called the equatorial axis.

**Q13: When is the torque on a dipole is maximum?**

**Ans:** When the axis of the dipole is perpendicular to the field.

**Q14: When is the torque on a dipole is minimum?**

**Ans: **When the axis of the dipole is parallel to the field.

**Q15: When an electric dipole is in stable equilibrium in an electric field?**

**Ans:** When dipole moment is parallel to the electric field.

**Q16: What is the electric dipole moment?**

**Ans: **Â It is the measure of the strength of electric dipole. Its magnitude is equal to the product of the magnitude of any one charge and the distance between them.

**Q17: Give an example for the electric dipole.**

**Ans:** A pair electric charge of two opposite sign and equal magnitude separated by a distance.

**Q18: Give the expression for the magnitude of an electric dipole.**

**Ans: **p = 2qa

Stay tuned with BYJU’S to learn more Physics concepts with the help of interactive video lessons.