Physical Sciences 3 Final: Lecture 3a

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fuchsiamole391

10 Jun 2019

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Document Summary

It is equal to minus the gradient of the electric potential: E is a vector field, defined at every point in space. The electric force on a charge is given by: opposite direction of. If q is negative, the force is in the. The magnitude of the electric field from a single point charge is e = The field points away from a positive charge and towards a negative charge. A pair of equal and opposite charges q separated by a distance d is a dipole, with dipole moment p = qd. A dipole in an electric field will feel a torque that will tend to align the dipole moment with the applied field. The electric field in a parallel-plate capacitor is uniform: The electric field inside a dielectric is reduced by a factor , called the dielectric constant. As a rule of thumb, in the presence of a dielectric you should replace everywhere .

Related Questions

An electric dipole consists of two opposite charges +/- q separated by a small distance (s). The product p=qs is called the dipole moment. The following figure shows an electric dipole perpendicular to an electric field E.(Figure 1)

Find an expression in terms of p and E for the magnitude of the torque that the electric field exerts on the dipole.

silverferret259

Consider an electric dipole whose dipole moment (a vector pointing from the negative charge to the positive charge) is oriented at an angle with respect to the y-axis. There is an external electric field of magnitude E (independent of the field produced by the dipole) pointing in the positive y-direction. The positive and negative ends of the dipole have charges +q and -q, respectively, and the two charges are a distance d apart. The dipole has a moment of inertia I about its center of mass. It will help you to imagine that the dipole is free to rotate about a pivot through its center.

A) What is the net force that the dipole experiences due to the electric field?

B) What is , the magnitude of the torque that the electric field exerts about the center of mass of the dipole?

C) Using the above result, find the potential energy associated with the dipole's orientation in the field as a function of the angle shown in the figure. Take the zero of the potential to occur when the dipole is at angle ; that is , .