Physics 2 Chapter 24 review questions

Two point charges lie along the x axis. One charge, located at the origin, has a magnitude +2q. The other charge of unknown magnitude and sign is located at x = 5 units. If the electric potential at x = 4 units is equal to zero volts, what is the magnitude and sign of the second point charge?

+q/2

The drawing shows four points surrounding an electric dipole. Which one of the following expressions best ranks the electric potential at these four locations?

1 > 2 = 4 > 3

The electric potential of an uncharged, spherical conductor with a radius of 0.1 m is 10 V. If the sphere is located in a region of space with no electric fields, what is the electric potential at a point located 2 m from the center of the sphere?

10V

A proton is moved from point B to point A in an electric field as shown. As a result of its movement, its potential increases to V. If three protons are moved from point B to A, how much will the electric potential of the protons increase?

3V because you are moving three electrons

Four point charges are individually brought from infinity and placed at the corners of a square as shown in the figure. Each charge has the identical value +Q. The length of the diagonal of the square is 2a. What is the electric potential at the center of the square?

4kQ/a add each point kQ/a

Points P and Q are separated by a distance of 0.10 m in a uniform electric field. The potential difference between points P and Q is 55 V. What is the magnitude of the electric field?

550 V/m divide volts by distance

Why is an electrostatic force considered a conservative force? a) Charged particles do not experience friction, which is a nonconservative force. b) The energy required to move a charged particle around a closed path is equal to zero joules. c) The work required to move a charged particle from one point to another does not depend upon the path taken. d) Answers (a) and (b) are both correct. e) Answers (b) and (c) are both correct.

Answers b and c are both correct

Point charge A is located at point A and point charge B is at point B. Points A and B are separated by a distance r. To determine the electric potential at the midpoint along a line between points A and B, which of the following mathematical approaches is correct?

The algebraic sum of the two electric potentials is determined at a distance r/2 from each of the charges, making sure to include the signs of the charges.

The potential difference between an initial point and a final point can be calculated using . Under what circumstances is the potential difference equal to zero volts?

The electric field is perpendicular to the path at all points between the initial and final points.

A uniform electric field is directed parallel to the +y axis. If a positive test charge begins at the origin and moves upward along the y axis, how does the electric potential vary, if at all?

The electric potential will decrease with increasing y.

Which one of the following phrases best describes the electric potential of a charged particle? a) the total force exerted on or by the charged particle b) the force per unit charge c) the potential energy of the particle relative to infinity d) the potential energy per unit charge e) the potential energy per unit force on the particle

The potential energy per unit charge

When you calculate the potential at some point P due to a continuous charge distribution, the sign for the potential can be troublesome. If the charge distribution is negative, should the quantities dq and l represent negative quantities?

The signs can be ignored; and at the end of the calculation inserted. The potential is negative if the charge distribution is negative

Consider the two charged particles. One charge located on the y axis has a value -2q and is located at a distance r from the origin, point O. The other charge has a value -q and is located at a distance 2r from the origin along the x axis. Which one of the following statements concerning the electric potential at the origin is true?

The total electric potential at the origin is equal to -5kq/2r.

Two electrons are separated by a distance R. If the distance between the charges is increased to 2R, what happens to the total electric potential energy of the system?

The total electric potential energy of the system would decrease to one half its initial value.

A uniform electric field is directed in the negative x direction. If you were to move a positive charge in the positive x direction, how would the total energy of the positive charge / electric field system change, if at all?

The total energy of the system would increase.

A force is exerted on a positively-charged particle that moves the particle in the direction opposite to that of an electric field. Which one of the following statements concerning the work performed in this movement is true?

The work done on the particle has a negative sign.

A positive charge is located at the origin. What is the direction of the electric potential of the positive charge?

There is no direction since the electric potential is a scalar quantity.

An electron, which has a charge of 1.60 × 10-19 C, is released at rest in a uniform electric field of magnitude 120 N/C. What is the potential energy of the electron just before it is released from rest?

Too little information is given to determine an answer.

Which of the following choices represents the quantity that is equal to the electric potential?

U/q

Consider the four cases shown of a charged particle located some distance from a point P. The quantity of charge and the distances vary. Note that the drawings are not necessarily drawn to scale. Which of the following expressions correctly ranks the electric potential energy at the point P for these four cases? (look at slide 6 for picture)

U2 > U1 > U3 > U4

A positively-charged particle is held at point A between two parallel metal plates. The plate on the left has a net positive charge +q and the plate on the right has a net negative charge -q. The particle is then moved to point B. How does the electric potential energy at point A compare with that at point B?

UA > UB

Consider the four arrangements of three point charges. Rank the values of the total electric potential at point P in each case in descending order (with the largest first)

VC > VB > VD > VA

A sphere has a radius R and a total charge Q uniformly distributed throughout its volume. Where is the electric potential of the sphere a minimum?

at infinity

Electric potential energy is defined in a similar manner to the gravitational potential energy. Complete the following statement: These two potential energies are analogous to each other because

both the electric and gravitational forces are conservative forces.

Consider the equipotential lines shown in the box. The labeled cases indicate electric field line drawings. Which of these cases best matches the equipotential lines shown? (look at slide 5 for picture)

case 1

A conducting sphere is connected via a wire to the ground. For a very short time, electrons move from the ground to the sphere. Then, no more electrons move to the sphere. Complete the following sentence: Before the wire was connected, the sphere's electric potential had a

positive value.

Complete the following statement: Along an equipotential surface,

the electric field lines are perpendicular to the surface.

Which of the following units are the SI units for the electric potential?

volt(V)

An electric dipole is situated on the y axis as shown. The two charges of opposite sign are of equal magnitude Q = 2.0 C. Determine the magnitude of the electric potential at point P.

zero volts because all the m's cancel out one another