AP Physics C: Electricity and Magnetism Practice Quiz: Inductance
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Test your understanding with short quizzes. This quiz has 11 questions to check your progress.
Question 1 of 11
All Questions (11)
A) The ability to store energy in an electric field.
B) The opposition to the flow of a steady electrical current.
C) The tendency of a conductor to oppose a change in electrical current.
D) The generation of a magnetic field from a stationary charge.
Correct Answer: C
The content explicitly states, 'Inductance is the tendency of a conductor to oppose a change in electrical current.' Option B describes resistance, and option A describes capacitance.
A) As potential energy in an electric field.
B) As kinetic energy of the moving charges.
C) As chemical energy within its core material.
D) As energy within the magnetic field generated by the current.
Correct Answer: D
The provided text states, 'Inductors store energy in the magnetic field that is generated by current in the inductor.'
A) Increasing the length (ℓ) of the solenoid.
B) Decreasing the cross-sectional area (A) of the solenoid.
C) Increasing the cross-sectional area (A) of the solenoid.
D) Using a thinner wire for the turns.
Correct Answer: C
The formula for the inductance of a solenoid is $L=\frac{\mu_{core}N^{2}A}{\ell}$. Inductance (L) is directly proportional to the cross-sectional area (A). Therefore, increasing the area will increase the inductance. Increasing the length (ℓ) would decrease the inductance.
A) It is halved.
B) It is doubled.
C) It is quadrupled.
D) It remains the same.
Correct Answer: C
Inductance (L) is proportional to the square of the number of turns (N²), as shown in the equation $L=\frac{\mu_{core}N^{2}A}{\ell}$. If N is doubled, the new inductance will be proportional to (2N)², which is 4N². Therefore, the inductance is quadrupled.
A) the current is at its maximum steady value.
B) the current is zero and not changing.
C) the rate of change of the current is at its maximum.
D) the energy stored in the inductor is zero.
Correct Answer: C
The equation $\mathcal{E}_{induced}=-L\frac{dI}{dt}$ shows that the induced EMF is directly proportional to the rate of change of current (dI/dt). Therefore, the EMF will have the greatest magnitude when the current is changing most rapidly.
A) 6.0 J
B) 12 J
C) 18 J
D) 36 J
Correct Answer: C
The energy stored in an inductor is given by the equation $U_{L}=\frac{1}{2}LI^{2}$. Plugging in the values: $U_{L}=\frac{1}{2}(4.0 \text{ H})(3.0 \text{ A})^{2} = \frac{1}{2}(4.0)(9.0) = 18 \text{ J}$.
A) 2.5 V
B) 5 V
C) 25 V
D) 50 V
Correct Answer: C
The induced EMF is given by $\mathcal{E}_{induced}=-L\frac{dI}{dt}$. The rate of change of current, $\frac{dI}{dt}$, is $\frac{5 \text{ A} - 0 \text{ A}}{2 \text{ s}} = 2.5 \text{ A/s}$. The magnitude of the EMF is $|-L\frac{dI}{dt}| = |-(10 \text{ H})(2.5 \text{ A/s})| = 25 \text{ V}$.
A) L/4
B) L
C) 2L
D) 4L
Correct Answer: D
The original inductance is $L=\frac{\mu_{core}N^{2}A}{\ell}$. The new solenoid has length $\ell' = \ell/2$ and area $A' = 2A$. The new inductance is $L'=\frac{\mu_{core}N^{2}A'}{\ell'} = \frac{\mu_{core}N^{2}(2A)}{(\ell/2)} = 4\frac{\mu_{core}N^{2}A}{\ell} = 4L$.
A) The inductance decreases significantly.
B) The inductance increases significantly.
C) The inductance remains unchanged, but it can store more energy.
D) The inductance remains unchanged, but the induced EMF is greater for the same change in current.
Correct Answer: B
According to the formula $L=\frac{\mu_{core}N^{2}A}{\ell}$, the inductance L is directly proportional to the magnetic permeability of the core, $\\mu_{core}$. Since the ferromagnetic core has a much higher permeability than air, the inductance will increase significantly.
A) 4U
B) 2U
C) U/2
D) U/4
Correct Answer: D
The energy stored in an inductor is given by $U_{L}=\frac{1}{2}LI^{2}$. Energy is proportional to the square of the current (I²). If the current is changed to I/2, the new energy $U'_{L}$ will be proportional to $(I/2)² = I²/4$. Therefore, the new energy is U/4.
A) 1/3
B) 3
C) 9
D) 1/9
Correct Answer: C
First, find the relationship between the inductances. $L_1 \propto N^2$ and $L_2 \propto (3N)^2 = 9N^2$. Therefore, $L_2 = 9L_1$. Next, use the energy storage equation, $U_{L}=\frac{1}{2}LI^{2}$. The ratio of the energies is $\frac{U_2}{U_1} = \frac{\frac{1}{2}L_2 I^2}{\frac{1}{2}L_1 I^2} = \frac{L_2}{L_1} = \frac{9L_1}{L_1} = 9$.