EM 3 Section 5: Electric Dipoles

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What is the physical significance of the dipole moment P in the far-field expansion of the potential?

It represents the distance from the origin
It represents the electric field strength
It represents the orientation of the electric dipole (correct)
It represents the total net charge

What is the dominant term in the far-field expansion of the potential when the total charge Q vanishes?

The dipole term (correct)
The monopole term
The octupole term
The quadrupole term

In the far-field limit, what is the characteristic shape of the electric field of a dipole?

Cylindrical symmetry (correct)
Spherical symmetry
Linear symmetry
Toroidal symmetry

Why is the far-field expansion of the potential in powers of 1/r?

Because the distance from the origin is large compared to the size of the charge distribution (A) Signup and view all the answers

What is the mathematical property of each term in the far-field expansion of the potential?

Each term is a solution of Laplace's equation (D) Signup and view all the answers

What is the physical significance of the quadrupole moment Qij in the far-field expansion of the potential?

It represents the distribution of charge in the quadrupole (C) Signup and view all the answers

What is the difference in the far-field limit of the electric field of a dipole and a point charge?

1/r^2 vs 1/r^3 (B) Signup and view all the answers

What is the physical significance of the ideal dipole approximation?

It is a useful approximation for understanding the behavior of media. (A) Signup and view all the answers

What is the direction of the electric field of a dipole in the far-field limit?

Parallel to the direction of the dipole moment. (A) Signup and view all the answers

What is the purpose of calculating the potential energy of a dipole in an external electric field?

To determine the force on the dipole. (B) Signup and view all the answers

What is the condition for the minimization of the potential energy of a dipole in an external electric field?

The dipole is parallel to the external field. (C) Signup and view all the answers

What is the change in potential energy required to reverse the direction of a dipole in an external electric field?

2p|Eext| (C) Signup and view all the answers

What is the direction of the vector a in the definition of an electric dipole moment?

From the negative to the positive charge (C) Signup and view all the answers

What is the electric potential of a dipole in the far field limit?

qa cos / (40 r) (A) Signup and view all the answers

What is the equation that the electric potential of a dipole must satisfy away from the charges?

Laplace's equation (B) Signup and view all the answers

What is the coordinate system in which the components of the electric field of a dipole are simplest?

Spherical polar coordinates (B) Signup and view all the answers

What is the expression for the electric field of a dipole in a coordinate-free form?

3(p r)r / (40 r^3) - p / (40 r^2) (D) Signup and view all the answers

EM 3 Section 5: Electric Dipoles

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