AP Physics C: Electricity and Magnetism Unit 2 Practice Test & Exam | 18 Questions

Questions 1-3 refer to the following information and diagram.

1. At which of the labeled points is the magnitude of the electric field the greatest?

(A)Point A(B)Point B(C)Point C(D)The magnitude of the electric field is the same at all three points.

2. How much work is done by the electric field on a proton of charge $+e$ as it moves from point A to point B?

(A)$-20$ eV(B)$-10$ eV(C)$+10$ eV(D)$+20$ eV

3. Which of the following vectors best represents the direction of the electric field at point B?

(A)Pointing toward the +20 V line(B)Pointing toward the -20 V line(C)Tangent to the 0 V line(D)It is impossible to determine without knowing the source charges.

Questions 4-6 refer to the following information and diagram.

4. What is the total electric potential energy of the system of three charges?

(A)$-\frac{3}{4\pi\epsilon_0}\frac{Q^2}{s}$(B)$-\frac{1}{4\pi\epsilon_0}\frac{Q^2}{s}$(C)$\frac{1}{4\pi\epsilon_0}\frac{Q^2}{s}$(D)$\frac{3}{4\pi\epsilon_0}\frac{Q^2}{s}$

5. What is the electric potential at point P, the center of the triangle?

(A)$-\frac{2Q}{4\pi\epsilon_0 s}$(B)0(C)$\frac{\sqrt{3}Q}{4\pi\epsilon_0 s}$(D)The electric potential cannot be determined because the distance from a vertex to the center is not given in terms of $s$.

6. A fourth charge, $+q$, is brought from infinitely far away and placed at point P. The work done by the external agent to place the charge at P is $W$. If the charge at the top vertex is changed from $+Q$ to $-Q$, what is the new work $W'$ required to bring the charge $+q$ from infinity to point P?

(A)$W' < W$, and $W'$ could be negative.(B)$W' < W$, but $W'$ must be positive.(C)$W' > W$(D)$W' = W$

Questions 7-9 refer to the following graph.

7. What is the magnitude of the electric field at $x = 1$ m?

(A)0 V/m(B)5 V/m(C)10 V/m(D)20 V/m

8. In which region is the magnitude of the electric field greatest?

(A)$0 < x < 2$ m(B)$2 < x < 4$ m(C)$4 < x < 6$ m(D)The magnitude of the field is constant for all $x$.

9. A proton is released from rest at $x = 2.5$ m. Which of the following best describes the subsequent motion of the proton?

(A)It accelerates in the positive x-direction.(B)It accelerates in the negative x-direction.(C)It remains at rest.(D)It moves with constant velocity in the positive x-direction.

10. An electron is accelerated from rest through a potential difference of 5000 V. What is the final speed of the electron, assuming it is non-relativistic? (mass of electron $m_e = 9.1 \times 10^{-31}$ kg, charge of electron $e = 1.6 \times 10^{-19}$ C)

(A)$2.1 \times 10^6$ m/s(B)$4.2 \times 10^7$ m/s(C)$8.4 \times 10^7$ m/s(D)$1.8 \times 10^8$ m/s

11. Consider a point P located exactly midway between a charge of $+Q$ and a charge of $-Q$. At point P, which of the following statements is true?

(A)The electric field is zero, and the electric potential is zero.(B)The electric field is non-zero, and the electric potential is zero.(C)The electric field is zero, and the electric potential is non-zero.(D)The electric field is non-zero, and the electric potential is non-zero.

12. Two point charges, $q1 = +4.0$ nC and $q2 = -6.0$ nC, are separated by a distance of 3.0 cm. What is the electric potential energy of this two-charge system? (Use $k = 9 \times 10^9$ N·m²/C²)

(A)$-7.2 \times 10^{-6}$ J(B)$-2.4 \times 10^{-5}$ J(C)$+2.4 \times 10^{-5}$ J(D)$+7.2 \times 10^{-6}$ J

13. The electric field in a region of space is directed along the x-axis and is given by the function $\vec{E} = (6x^2) \hat{i}$ V/m. What is the potential difference $VB - VA$ between point A at $x = 1$ m and point B at $x = 3$ m?

(A)-104 V(B)-52 V(C)+52 V(D)+104 V

14. The electric potential in a region of space is given by the function $V(x,y) = 3x^2y - 2y^2z$. What is the y-component of the electric field, $E_y$, at the point $(x=1, y=2, z=3)$?

(A)-9 V/m(B)-3 V/m(C)3 V/m(D)9 V/m

15. A charge of $+Q$ is located at $x=0$, and a charge of $-4Q$ is located at $x=d$. At which of the following locations on the x-axis is the total electric potential equal to zero? (Assume potential is zero at infinity).

(A)$x = d/5$(B)$x = d/3$(C)$x = 2d/3$(D)$x = 4d/3$

16. An alpha particle (charge $+2e$) is accelerated through a potential difference $\Delta V$. It gains a kinetic energy of 5.0 MeV. What is the value of the potential difference $\Delta V$?

(A)2.5 MV(B)5.0 MV(C)7.5 MV(D)10.0 MV

17. A charge $+q$ is moved from point A to point B in the vicinity of a fixed point charge $+Q$. Path 1 is a direct straight line. Path 2 is a curved path. Let $W1$ be the work done by the electric field along Path 1, and $W2$ be the work done by the electric field along Path 2. Which statement is correct?

(A)$W1 > W2$(B)$W1 < W2$(C)$W1 = W2$(D)The relationship between $W1$ and $W2$ cannot be determined without knowing the exact shape of Path 2.

18. A thin insulating ring of radius $R$ has a total charge $+Q$ uniformly distributed along its circumference. The electric potential at the center of the ring is $V_0$. If the radius of the ring is doubled to $2R$ while the total charge remains $+Q$, what is the new electric potential at the center?

(A)$V_0 / 4$(B)$V_0 / 2$(C)$V_0$(D)$2V_0$

AP Physics C: Electricity and Magnetism Unit 2: Electric Potential Practice Exam

Exam Details

A. Multiple-Choice Questions (18 Questions)

AP Physics C: Electricity and Magnetism Unit 2: Electric Potential Practice Exam

Exam Details

A. Multiple-Choice Questions (18 Questions)