AP Physics C: Electricity and Magnetism Unit 6 Practice Test & Exam | 18 Questions

Questions 1-3 refer to the following scenario.

1. When the leading edge of the loop is at position $x$, where $0 < x < w$, what is the magnetic flux $\Phi_B$ through the loop?

(A)$0$(B)$Bwh$(C)$Bxh$(D)$B(w-x)h$

2. As the loop enters the magnetic field, what is the direction of the induced current in the loop?

(A)Clockwise(B)Counterclockwise(C)Into the page(D)There is no induced current.

3. While the loop is entering the field, a magnetic force acts on it. What is the magnitude of this magnetic force?

(A)$\frac{B^2h^2v}{R}$(B)$\frac{B^2w^2v}{R}$(C)$Bhw$(D)$Bhv$

Questions 4-5 refer to the following scenario.

4. What is the magnitude of the induced electromotive force (EMF) in the loop?

(A)$k\pi r^2$(B)$(B_0+kt)\pi r^2$(C)$2\pi r k$(D)$\frac{k\pi r^2}{R}$

5. The changing magnetic field induces a non-conservative electric field $\vec{E}$ within the wire. What is the magnitude of this induced electric field?

(A)$k\pi r^2$(B)$\frac{kr}{2}$(C)$\frac{kR}{2\pi r}$(D)$kr$

6. A student correctly uses Lenz's Law to determine that as the magnetic field described by $B(t) = B_0 - kt$ (where $k$ is positive) decreases, the induced current flows clockwise. If the experiment is repeated with a new wire loop that has the same radius but twice the resistance, which of the following statements is true about the new induced current and its magnetic field?

(A)The induced current will be halved, and its magnetic field will still oppose the change in flux.(B)The induced current will be doubled, and its magnetic field will now aid the change in flux.(C)The induced current will be halved, and its magnetic field will now aid the change in flux.(D)The induced current will remain the same, as it depends only on the rate of change of flux.

Questions 7-9 refer to the circuit diagram below.

7. Immediately after the switch is closed (at $t=0^+$), what is the current through the resistor $R$?

(A)$0$(B)$\frac{\mathcal{E}}{R}$(C)$\frac{\mathcal{E}}{L}$(D)The current is infinite.

8. A very long time after the switch has been closed ($t \to \infty$), what is the potential difference across the inductor $L$?

(A)$\mathcal{E}$(B)$\frac{\mathcal{E}R}{L}$(C)$\frac{\mathcal{E}}{2}$(D)$0$

9. The time constant of the circuit is $\tau$. If the inductance $L$ is doubled and the resistance $R$ is halved, what is the new time constant $\tau'$?

(A)$\frac{1}{4}\tau$(B)$\tau$(C)$2\tau$(D)$4\tau$

Questions 10-12 refer to the circuit diagram below.

10. What is the maximum current $I_{max}$ that flows through the inductor during the subsequent oscillations?

(A)$Q_{max}\sqrt{LC}$(B)$\frac{Q_{max}}{\sqrt{LC}}$(C)$\frac{Q_{max}}{LC}$(D)$\frac{Q_{max}^2}{2C}$

11. The circuit oscillates with an angular frequency $\omega$. If the capacitance is changed to $4C$ and the inductance is changed to $L/9$, what is the new angular frequency $\omega'$?

(A)$\frac{2}{3}\omega$(B)$\frac{3}{2}\omega$(C)$\frac{4}{9}\omega$(D)$\frac{9}{4}\omega$

12. Which of the following statements correctly describes the relationship between the charge $q(t)$ on the capacitor and the current $i(t)$ in the circuit?

(A)The current is at its maximum when the charge is at its maximum.(B)The current is zero when the charge is zero.(C)The current is at its maximum when the charge is zero.(D)The charge and current are always in phase with each other.

13. The self-inductance of a long, air-core solenoid depends on which of the following? I. The number of turns per unit length II. The cross-sectional area of the solenoid III. The current flowing through the solenoid

(A)I only(B)III only(C)I and II only(D)I, II, and III

14. A 50 mH inductor carries a steady current of 2.0 A. How much energy is stored in the magnetic field of the inductor?

(A)0.05 J(B)0.10 J(C)0.20 J(D)100 J

Refer to the figure below.

15. The current $I$ through a 2.0 H inductor varies with time $t$ as shown in the graph below. What is the magnitude of the induced EMF across the inductor between $t=2$ s and $t=4$ s?

(A)0 V(B)2.0 V(C)4.0 V(D)8.0 V

16. A circular loop of wire is held stationary in a very strong, uniform magnetic field of 5.0 T. The plane of the loop is perpendicular to the field lines. Which statement best describes the induced EMF in the loop?

(A)The induced EMF is very large because the magnetic field is very strong.(B)The induced EMF is zero because the magnetic flux is not changing.(C)The induced EMF is constant and non-zero because the magnetic flux is constant and non-zero.(D)The induced EMF depends on the resistance of the wire loop.

17. A bar magnet is moved toward a circular loop of conducting wire, with its north pole entering the loop first. The magnetic flux through the loop is increasing in the downward direction. Which of the following correctly describes the induced magnetic field created by the induced current?

(A)It points upward to oppose the increase in downward flux.(B)It points downward to aid the increase in downward flux.(C)It points in the same direction as the magnet's velocity.(D)It is zero because the magnet is a permanent magnet.

18. A straight conducting rod of length 0.50 m is moved at a constant speed of 4.0 m/s perpendicular to a uniform magnetic field of 0.20 T. The rod, its velocity, and the magnetic field are all mutually perpendicular. What is the motional EMF induced across the ends of the rod?

(A)0.10 V(B)0.40 V(C)1.0 V(D)4.0 V

AP Physics C: Electricity and Magnetism Unit 6: Electromagnetic Induction Practice Exam

Exam Details

A. Multiple-Choice Questions (18 Questions)

AP Physics C: Electricity and Magnetism Unit 6: Electromagnetic Induction Practice Exam

Exam Details

A. Multiple-Choice Questions (18 Questions)