CH 20

A uniform electric field of magnitude 7.5×105N/C points in the positive x direction. Find the change in electric potential energy of a 7.0-μC charge as it moves from the origin to the point (6.0 m, 0).

-32 J;

If the spacing between the plates in capacitor 1 is d, what should the spacing between the plates in capacitor 2 be to make the capacitance of the two capacitors equal?

2d

The electric potential at a certain distance from a point charge can be represented by V. What is the value of the electric potential at twice the distance from the point charge?

At twice the distance, the electric potential is V/2.

Which of the following statements are true? A. The potential energy of a test charge decreases as it moves along an equipotential surface. B. An equipotential surface is a three-dimensional surface on which the electric potential is the same at every point. C. The potential energy of a test charge increases as it moves along an equipotential surface. D. Electric field lines and equipotential surfaces are always mutually perpendicular. E. When all charges are at rest, the surface of a conductor is always an equipotential surface.

B. An equipotential surface is a three-dimensional surface on which the electric potential is the same at every point. D. Electric field lines and equipotential surfaces are always mutually perpendicular. E. When all charges are at rest, the surface of a conductor is always an equipotential surface.

Consider an air-filled charged capacitor. How can its capacitance be increased? A. increase the charge on the capacitor. B. Decrease the charge on the capacitor. C. Increase the spacing between the plates of the capacitor. D. Decrease the spacing between the plates of the capacitor. E. Increase the length of the wires leading to the capacitor plates.

B. Decrease the charge on the capacitor.

A negative charge moves in a direction opposite to that of an electric field. What happens to the energy associated with the charge? A. Both the electric potential energy and the kinetic energy of the charge decrease. B. The electric potential energy of the charge decreases, and the kinetic energy increases. C. The electric potential energy of the charge increases, and the kinetic energy decreases. D. The electric potential energy of the charge decreases, and the kinetic energy increases.Both the electric potential energy and the kinetic energy of the charge increase.

B. The electric potential energy of the charge decreases, and the kinetic energy increases.

What property of objects is best measured by their capacitance? a.the ability to conduct electric current b. the ability to distort an external electrostatic field c. the ability to store' charge

C. the ability to store charge

Consider a charged parallel-plate capacitor. How can its capacitance be halved? Check all that apply. Double the charge. Double the plate area. Double the plate separation. Halve the charge. Halve the plate area. Halve the plate separation.

Double the plate separation; Halve the charge.

A positive charge moves in a direction opposite to that of an electric field. What happens to the energy associated with the charge? A. Both the electric potential energy and the kinetic energy of the charge decrease. B. The electric potential energy of the charge decreases, and the kinetic energy increases. C. The electric potential energy of the charge increases, and the kinetic energy decreases. D. Both the electric potential energy and the kinetic energy of the charge increase

The electric potential energy of the charge increases, and the kinetic energy decreases.

Suppose two parallel-plate capacitors have the same charge Q, but the area of capacitor 1 is A and the area of capacitor 2 is 2A. If the spacing between the plates, d, is the same in both capacitors, and the voltage across capacitor 1 is V, what is the voltage across capacitor 2?

V/2 ( Since the voltage between two parallel plates is proportional to the electric field, capacitor 2 also has a lower voltage.)

A proton is released from rest in a region of space with a nonzero electric field. As the proton moves, does the electric potential energy of the system increase, decrease, or stay the same?

decrease (As the proton begins to move, its kinetic energy increases. The increase in kinetic energy is equal to the decrease in the electric potential energy of the system)

An electron is released from rest in a region of space with a nonzero electric field. As the electron moves, does the electric potential energy of the system increase, decrease, or stay the same?

decrease. (As the electron begins to move, its kinetic energy increases. The increase in kinetic energy is equal to the decrease in the electric potential energy of the system. )

The plates of a parallel-plate capacitor have constant charges of +Q and−Q. Do the following quantities increase, decrease, or remain the same as the separation of the plates is increase.. the capacitance

decreased

The plates of a parallel-plate capacitor have constant charges of +Q and−Q. Do the following quantities increase, decrease, or remain the same as the separation of the plates is increase the energy stored in the capacitor?

increaes

The plates of a parallel-plate capacitor have constant charges of +Q and−Q. Do the following quantities increase, decrease, or remain the same as the separation of the plates is increase.. the potential difference between the plates

increase

The plates of a parallel-plate capacitor have constant charges of +Q and−Q. Do the following quantities increase, decrease, or remain the same as the separation of the plates is increased?t he electric field between the plates

stay the same