Electric Dipole Potential Energy and Work

The video tutorial covers the concept of potential energy in an external electric field, explaining how work is done to bring charges from infinity to a point in the field. It also discusses the potential energy of an electric dipole in a uniform electric field, detailing the torque experienced by the dipole and the work done in rotating it. The tutorial provides mathematical expressions for calculating potential energy and work done in these scenarios.

What is the work done to bring a charge q1 from infinity to a point in an electric field?

• q1 divided by the potential at that point

• q1 multiplied by the potential at that point

• Zero, since the charge is from infinity

• The potential at that point divided by q1

When bringing a second charge Q2 into the field, what additional work must be considered?

• Work done against the gravitational field

• No additional work is needed

• Work done against the field due to q1

• Work done against the magnetic field

What is the expression for the total potential energy of a system of two charges in an external field?

• The sum of the potentials at R1 and R2

• q1 times the potential at R1 plus Q2 times the potential at R2

• q1 times Q2 divided by the distance between them

• The product of the potentials at R1 and R2

What is the torque experienced by an electric dipole in a uniform electric field?

• P times the cosine of the angle with the field

• P times the sine of the angle with the field

• P divided by the sine of the angle with the field

• Zero, since the field is uniform

How is the work done in rotating a dipole stored?

• As kinetic energy

• As thermal energy

• As potential energy

• As mechanical energy

What is the potential energy of a dipole initially perpendicular to the field?

• Zero, since it is perpendicular

• Negative P times the cosine of the angle with the field

• P times the cosine of the angle with the field

• P times the sine of the angle with the field

What happens to the potential energy of a dipole as it rotates from 90° to an angle θ?

• It becomes zero

• It remains constant

• It decreases

• It increases

What is the expression for the work done in rotating a dipole from angle θ1 to θ2?

• P times the sum of cosines of θ1 and θ2

• P times the difference of cosines of θ1 and θ2

• P times the product of cosines of θ1 and θ2

• P times the sine of the difference of θ1 and θ2

What is the potential energy of a dipole in terms of its angle with the field?

• Negative P times the cosine of the angle

• P times the cosine of the angle

• P times the sine of the angle

• Zero, since it is in a uniform field

What is the effect of the external field on the potential energy of a dipole?

• It decreases the potential energy

• It makes the potential energy zero

• It increases the potential energy

• It has no effect on the potential energy