AP Physics 2 Flashcards: Magnetic Fields

What this deck covers

This deck focuses on Magnetic Fields, giving you a quick way to review the definitions, rules, and examples that matter most for AP Physics 2.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is the direction of the magnetic force on a positive charge moving in a magnetic field?

Answer: Perpendicular to both velocity and magnetic field. Cross product in Lorentz force creates perpendicular direction.

Flashcard 2: State the formula for the magnetic field inside a toroid.

Answer: $B = \frac{\mu_0 n I}{2\pi r}$. Toroidal geometry confines field within the torus structure.

Flashcard 3: Choose the correct expression for the force between two parallel conductors carrying current.

Answer: $F/L = \frac{\mu_0 I_1 I_2}{2\pi d}$. Force per unit length between parallel current-carrying conductors.

Flashcard 4: State the formula for the magnetic field inside a solenoid.

Answer: $B = \mu_0 n I$. Field is uniform inside; $n$ is turns per unit length.

Flashcard 5: State the formula for the magnetic field inside a solenoid.

Answer: $B = \mu_0 n I$. Field is uniform inside; $n$ is turns per unit length.

Flashcard 6: What is the definition of a Tesla?

Answer: 1 Tesla = 1 N/(A·m). Force per unit current per unit length in magnetic field.

Flashcard 7: State the expression for the force on a moving charge in an electric and magnetic field.

Answer: $F = q(E + v \times B)$. Complete Lorentz force including both electric and magnetic components.

Flashcard 8: What is the Lorentz force equation?

Answer: $F = q(E + v \times B)$. Combined electric and magnetic forces on a charged particle.

Flashcard 9: What is the formula for the cyclotron frequency of a charged particle?

Answer: $f = \frac{qB}{2\pi m}$. Frequency of circular motion in uniform magnetic field.

Flashcard 10: What is the formula for the energy stored in a magnetic field?

Answer: $U = \frac{1}{2}LI^2$. Energy stored depends on inductance $L$ and current squared.

Flashcard 11: Determine the magnetic force on a wire if $I = 3 \, A$, $L = 2 \, m$, and $B = 0.5 \, T$.

Answer: 3 N. Using $F = ILB$ for perpendicular orientation: $3 \times 2 \times 0.5$.

Flashcard 12: State the formula for the magnetic field at the center of a circular loop of wire.

Answer: $B = \frac{\mu_0 I}{2R}$. Field at center is half that of infinite solenoid.

Flashcard 13: Identify the main factor that affects the magnitude of the magnetic force on a conductor.

Answer: Current (I). Force is directly proportional to current flowing through conductor.

Flashcard 14: What is the Lorentz force equation?

Answer: $F = q(E + v \times B)$. Combined electric and magnetic forces on a charged particle.

Flashcard 15: State the unit of magnetic field strength in the SI system.

Answer: Tesla (T). Named after Nikola Tesla; equivalent to $\text{Wb/m}^2$.

Flashcard 16: State the formula for the magnetic field at a point on the axis of a current loop.

Answer: $B = \frac{\mu_0 I R^2}{2(x^2 + R^2)^{3/2}}$. Field strength decreases rapidly with distance from loop center.

Flashcard 17: Calculate the magnetic field strength 1 m away from a 5 A current-carrying wire.

Answer: $1 \times 10^{-6} \text{ T}$. Using $B = \frac{\mu_0 I}{2\pi r}$ with given values.

Flashcard 18: Identify the force direction if a proton moves south in a magnetic field pointing upwards.

Answer: West. Using right-hand rule: velocity south, field up gives force west.

Flashcard 19: Find the direction of force on an electron moving north in a magnetic field directed east.

Answer: Downward. Electron has negative charge; force opposes right-hand rule direction.

Flashcard 20: What is the formula for the magnetic field due to a long, straight current-carrying wire?

Answer: $B = \frac{\mu_0 I}{2\pi r}$. Field decreases as $1/r$ with distance from wire.

Flashcard 21: What is the principle behind the operation of a galvanometer?

Answer: Torque on a current loop in a magnetic field. Current loop rotates in magnetic field producing measurable deflection.

Flashcard 22: Find the magnetic field strength inside a solenoid with $n = 1000 \, \text{turns/m}$ and $I = 0.01 \, \text{A}$.

Answer: $1.26 \times 10^{-5} \text{ T}$. Using $B = \mu_0 n I$ with given turn density and current.

Flashcard 23: Choose the correct expression for the force between two parallel conductors carrying current.

Answer: $F/L = \frac{\mu_0 I_1 I_2}{2\pi d}$. Force per unit length between parallel current-carrying conductors.

Flashcard 24: What is the relationship between magnetic moment and torque?

Answer: $\tau = \mu \times B$. Torque is cross product of magnetic moment and field vectors.

Flashcard 25: Identify the variable that denotes the number of turns per unit length in a solenoid.

Answer: $n$. Turn density determines magnetic field strength in solenoid.

Flashcard 26: What is the formula for the Hall voltage in a conductor?

Answer: $V_H = \frac{IB}{net}$. Hall effect: voltage across conductor in magnetic field.

Flashcard 27: What is the definition of magnetic flux density?

Answer: Magnetic flux per unit area. Magnetic field $B$ represents flux density through a surface.

Flashcard 28: State the formula for the magnetic field at the center of a circular loop of wire.

Answer: $B = \frac{\mu_0 I}{2R}$. Field at center is half that of infinite solenoid.

Flashcard 29: What is the formula for the magnetic torque on a current loop?

Answer: $\tau = nIAB \sin \theta$. Torque depends on loop area $A$ and angle $\theta$ with field.

Flashcard 30: State the formula for the magnetic field inside a toroid.

Answer: $B = \frac{\mu_0 n I}{2\pi r}$. Toroidal geometry confines field within the torus structure.

Flashcard 31: What is the formula for the magnetic torque on a current loop?

Answer: $\tau = nIAB \sin \theta$. Torque depends on loop area $A$ and angle $\theta$ with field.

Flashcard 32: What is the formula for the magnetic force on a moving charge?

Answer: $F = q(v \times B)$. Cross product shows force is perpendicular to both $v$ and $B$.

Flashcard 33: What is the value of the permeability of free space ($\mu_0$)?

Answer: $4\pi \times 10^{-7} \, \text{T}\cdot\text{m/A}$. Fundamental constant relating magnetic field to current.

Flashcard 34: What is the formula for the energy stored in a magnetic field?

Answer: $U = \frac{1}{2}LI^2$. Energy stored depends on inductance $L$ and current squared.

Flashcard 35: What is the formula for the Hall voltage in a conductor?

Answer: $V_H = \frac{IB}{net}$. Hall effect: voltage across conductor in magnetic field.

Flashcard 36: Calculate the magnetic field strength 1 m away from a 5 A current-carrying wire.

Answer: $1 \times 10^{-6} \text{ T}$. Using $B = \frac{\mu_0 I}{2\pi r}$ with given values.

Flashcard 37: State the unit of magnetic field strength in the SI system.

Answer: Tesla (T). Named after Nikola Tesla; equivalent to $\text{Wb/m}^2$.

Flashcard 38: State the expression for the force on a moving charge in an electric and magnetic field.

Answer: $F = q(E + v \times B)$. Complete Lorentz force including both electric and magnetic components.

Flashcard 39: Identify the variable that denotes the number of turns per unit length in a solenoid.

Answer: $n$. Turn density determines magnetic field strength in solenoid.

Flashcard 40: What is the unit of magnetic flux?

Answer: Weber (Wb). Named after Wilhelm Weber; measures magnetic field through area.

Flashcard 41: Identify the rule used to determine the direction of the magnetic force on a moving charge.

Answer: Right-hand rule. Point fingers along $v$, curl toward $B$, thumb shows force direction.

Flashcard 42: What is the formula for the magnetic field due to a long, straight current-carrying wire?

Answer: $B = \frac{\mu_0 I}{2\pi r}$. Field decreases as $1/r$ with distance from wire.

Flashcard 43: What is the principle behind magnetic levitation?

Answer: Repulsion of like magnetic poles. Like poles repel, creating upward force against gravity.

Flashcard 44: What is the formula for the magnetic force on a current-carrying wire?

Answer: $F = I(L \times B)$. Current $I$ and length $L$ replace charge and velocity in force equation.

Flashcard 45: What is the value of the permeability of free space ($\mu_0$)?

Answer: $4\pi \times 10^{-7} \, \text{T}\cdot\text{m/A}$. Fundamental constant relating magnetic field to current.

Flashcard 46: What is the formula for the magnetic force on a current-carrying wire?

Answer: $F = I(L \times B)$. Current $I$ and length $L$ replace charge and velocity in force equation.

Flashcard 47: Identify the main factor that affects the magnitude of the magnetic force on a conductor.

Answer: Current (I). Force is directly proportional to current flowing through conductor.

Flashcard 48: State the formula for the magnetic field at a point on the axis of a current loop.

Answer: $B = \frac{\mu_0 I R^2}{2(x^2 + R^2)^{3/2}}$. Field strength decreases rapidly with distance from loop center.

Flashcard 49: What is the unit of magnetic flux?

Answer: Weber (Wb). Named after Wilhelm Weber; measures magnetic field through area.

Flashcard 50: Identify the relationship between magnetic flux and magnetic field.

Answer: $\Phi_B = B \cdot A \cdot \cos \theta$. Flux depends on field strength, area, and orientation angle.

Flashcard 51: What is the relationship between magnetic moment and torque?

Answer: $\tau = \mu \times B$. Torque is cross product of magnetic moment and field vectors.

Flashcard 52: What is the definition of a Tesla?

Answer: 1 Tesla = 1 N/(A·m). Force per unit current per unit length in magnetic field.

Flashcard 53: What is the principle behind the operation of a galvanometer?

Answer: Torque on a current loop in a magnetic field. Current loop rotates in magnetic field producing measurable deflection.

Flashcard 54: Which device uses magnetic fields to separate charged particles by mass?

Answer: Mass spectrometer. Different masses follow different curved paths in magnetic field.

Flashcard 55: Which option correctly describes the Biot-Savart Law?

Answer: It relates magnetic fields to the currents which produce them. Fundamental law connecting magnetic fields to their current sources.

Flashcard 56: Find the magnetic force on a 2 C charge moving at 3 m/s perpendicular to a 4 T magnetic field.

Answer: 24 N. Using $F = qvB$ with perpendicular motion: $2 \times 3 \times 4 = 24$.

Flashcard 57: Identify the force direction if a proton moves south in a magnetic field pointing upwards.

Answer: West. Using right-hand rule: velocity south, field up gives force west.

Flashcard 58: Which device uses magnetic fields to separate charged particles by mass?

Answer: Mass spectrometer. Different masses follow different curved paths in magnetic field.

Flashcard 59: Determine the magnetic force on a wire if $I = 3 \, A$, $L = 2 \, m$, and $B = 0.5 \, T$.

Answer: 3 N. Using $F = ILB$ for perpendicular orientation: $3 \times 2 \times 0.5$.

Flashcard 60: What is the formula for the magnetic force on a moving charge?

Answer: $F = q(v \times B)$. Cross product shows force is perpendicular to both $v$ and $B$.

Flashcard 61: Find the direction of force on an electron moving north in a magnetic field directed east.

Answer: Downward. Electron has negative charge; force opposes right-hand rule direction.

Flashcard 62: Identify the rule used to determine the direction of the magnetic force on a moving charge.

Answer: Right-hand rule. Point fingers along $v$, curl toward $B$, thumb shows force direction.

Flashcard 63: What is the direction of the magnetic force on a positive charge moving in a magnetic field?

Answer: Perpendicular to both velocity and magnetic field. Cross product in Lorentz force creates perpendicular direction.

Flashcard 64: What is the expression for the magnetic field of a moving charge?

Answer: $B = \frac{\mu_0}{4\pi} \frac{q(v \times r)}{r^3}$. Biot-Savart law for field produced by moving point charge.

Flashcard 65: What is the formula for the cyclotron frequency of a charged particle?

Answer: $f = \frac{qB}{2\pi m}$. Frequency of circular motion in uniform magnetic field.

Flashcard 66: Which option correctly describes the Biot-Savart Law?

Answer: It relates magnetic fields to the currents which produce them. Fundamental law connecting magnetic fields to their current sources.

Flashcard 67: Find the magnetic force on a 2 C charge moving at 3 m/s perpendicular to a 4 T magnetic field.

Answer: 24 N. Using $F = qvB$ with perpendicular motion: $2 \times 3 \times 4 = 24$.

Flashcard 68: What is the principle behind magnetic levitation?

Answer: Repulsion of like magnetic poles. Like poles repel, creating upward force against gravity.

Flashcard 69: Find the magnetic field strength inside a solenoid with $n = 1000 \, \text{turns/m}$ and $I = 0.01 \, \text{A}$.

Answer: $1.26 \times 10^{-5} \text{ T}$. Using $B = \mu_0 n I$ with given turn density and current.

Flashcard 70: Identify the relationship between magnetic flux and magnetic field.

Answer: $\Phi_B = B \cdot A \cdot \cos \theta$. Flux depends on field strength, area, and orientation angle.

Flashcard 71: What is the expression for the magnetic field of a moving charge?

Answer: $B = \frac{\mu_0}{4\pi} \frac{q(v \times r)}{r^3}$. Biot-Savart law for field produced by moving point charge.

Flashcard 72: What is the definition of magnetic flux density?

Answer: Magnetic flux per unit area. Magnetic field $B$ represents flux density through a surface.