AP Physics C: Electricity and Magnetism Practice Quiz: Magnetic Fields
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Test your understanding with short quizzes. This quiz has 16 questions to check your progress.
Question 1 of 16
All Questions (16)
A) Stationary electric charges
B) Moving electric charges
C) Objects based solely on their mass
D) An electric field
Correct Answer: B
The provided content explicitly states that a magnetic field is a vector field used to determine the magnetic force exerted on 'moving electric charges, electric currents, or magnetic materials.' Stationary charges do not experience a magnetic force.
A) They must originate from a north pole and terminate on a south pole.
B) They must form closed loops.
C) They can start or end on isolated magnetic charges.
D) They are always parallel to the direction of electric current.
Correct Answer: B
The content specifies that 'Magnetic field lines must form closed loops, as described by Gauss's law for magnetism.' This implies that there are no magnetic monopoles where field lines could begin or end.
A) It will align perpendicular to the magnetic field lines.
B) It will be repelled from the strongest part of the field.
C) It will tend to align with the magnetic field.
D) It will spin continuously at a constant rate.
Correct Answer: C
The content states, 'A magnetic dipole, such as a magnetic compass, placed in a magnetic field will tend to align with the magnetic field.' The compass needle acts as a magnetic dipole.
A) The magnetic dipoles are randomly oriented.
B) The magnetic dipoles are predominantly aligned in the same direction.
C) The material has no magnetic dipoles.
D) The magnetic dipoles are aligned in opposing pairs, perfectly canceling each other out.
Correct Answer: B
The content indicates that the 'magnetic behavior of a material as a result of the configuration of magnetic dipoles in the material.' A strong magnetic material implies a configuration where the individual dipole effects add up, which occurs when they are predominantly aligned in the same direction. A random orientation would lead to no net magnetic effect.
A) The ability of a material to conduct electricity.
B) The force exerted by a magnetic field on a moving charge.
C) A property describing how a material's internal magnetic dipoles respond to an external magnetic field.
D) The density of magnetic field lines in a vacuum.
Correct Answer: C
The content introduces 'the magnetic permeability of a material' in the context of how magnetic dipoles are configured. Permeability is a measure of a material's ability to support the formation of a magnetic field within itself, which is directly related to how its internal dipoles respond. Option C correctly links permeability to the material's internal magnetic structure.
A) Magnetic fields are created only by electric currents.
B) The net magnetic flux through any closed surface is zero.
C) The magnetic force is always perpendicular to a particle's velocity.
D) The strength of a magnetic field is always constant.
Correct Answer: B
The integral $\oint\vec{B}\cdot d\vec{A}$ represents the total magnetic flux through a closed surface A. The equation states that this value is always zero. This means that for any closed surface, the amount of magnetic field lines entering the surface must equal the amount exiting, which is a direct consequence of the field lines forming closed loops.
A) Only a magnitude.
B) Both a magnitude and a direction.
C) Only a direction.
D) A constant value that does not change.
Correct Answer: B
A vector is a quantity that has both magnitude (strength) and direction. By defining the magnetic field as a 'vector field,' the content specifies that at every point, the field can be described by its strength and the direction it points.
A) The magnetic dipoles are all strongly aligned in one direction.
B) The material completely lacks atomic-level magnetic dipoles.
C) The magnetic dipoles are oriented randomly, so their effects cancel out on a large scale.
D) The magnetic dipoles are aligned with Earth's gravitational field.
Correct Answer: C
Based on the principle that magnetic behavior results from the 'configuration of magnetic dipoles,' a non-magnetic material like copper has a configuration where the net effect is zero. This is typically due to the random thermal orientation of its atomic dipoles, causing their individual magnetic fields to cancel each other out macroscopically.
A) Magnetic dipoles
B) Electric charges
C) Magnetic monopoles
D) Electric currents
Correct Answer: C
If magnetic monopoles (isolated north or south poles) existed, magnetic field lines could start on a north pole and end on a south pole, just as electric field lines start and end on charges. The requirement for closed loops, as described by Gauss's law for magnetism, is equivalent to the experimental observation that magnetic monopoles have never been found.
A) A proton moving through the field.
B) An electric current flowing in a wire.
C) A stationary electron within the field.
D) A small iron filing (a magnetic material).
Correct Answer: C
The content specifies that a magnetic field exerts a force on 'moving electric charges, electric currents, or magnetic materials.' A stationary electron is an electric charge, but since it is not moving, it would not experience a force from the magnetic field.
A) The dipoles remain randomly oriented, unaffected by the field.
B) The dipoles align strongly with the external field, enhancing the total field.
C) The dipoles are expelled from the material.
D) The dipoles align perpendicular to the external field, canceling it.
Correct Answer: B
This question synthesizes two concepts: magnetic permeability and dipole configuration. A material with high permeability responds strongly to a magnetic field. This strong response is caused by its internal magnetic dipoles aligning with the external field, which in turn enhances the total magnetic field within and around the material.
A) A diagram showing concentric circles of field lines around a current-carrying wire.
B) A diagram showing field lines emerging from a north pole and ending on a south pole of a bar magnet, which form closed loops by passing through the magnet.
C) A diagram showing magnetic field lines originating from a single point charge and extending outwards to infinity.
D) A diagram showing a uniform magnetic field represented by parallel, evenly spaced field lines.
Correct Answer: C
The content states that 'Magnetic field lines must form closed loops.' A diagram showing field lines originating from a single point and not returning would represent a magnetic monopole, which violates this fundamental rule and Gauss's law for magnetism. The other options represent valid magnetic field configurations.
A) The magnetic permeability of the material has permanently become zero.
B) The aligned magnetic dipoles were randomized by thermal energy and did not re-align.
C) The material has lost all its moving electric charges.
D) The magnetic field lines inside the material have been broken.
Correct Answer: B
The magnetic behavior of a material is due to the 'configuration of its magnetic dipoles.' In a permanent magnet, these dipoles are aligned. High temperatures provide thermal energy that disrupts this alignment, causing the dipoles to become randomly oriented. If cooled without an external field to re-align them, they remain random, and the material loses its macroscopic magnetism.
A) It will point toward the geographic East-West line.
B) It will point vertically upwards, away from the ground.
C) It will align with the local magnetic field lines of the Earth.
D) Its orientation will be random and unpredictable.
Correct Answer: C
The content states that a magnetic dipole 'will tend to align with the magnetic field.' A bar magnet is a magnetic dipole, and the Earth generates a magnetic field. Therefore, the magnet will align itself with the local direction of the Earth's magnetic field lines, which is the principle behind a compass.
A) A net force in the direction of the magnetic field.
B) A net force opposite to the direction of the magnetic field.
C) Zero.
D) A net force perpendicular to the magnetic field.
Correct Answer: C
While the content states a dipole will 'align' with the field, this alignment is caused by a net torque, not a net force. In a uniform magnetic field, the force on the north pole of the dipole is equal in magnitude and opposite in direction to the force on the south pole. These two forces cancel each other out, resulting in a net force of zero. A net force would only be present in a non-uniform (gradient) field.
A) Electric currents
B) Magnetic materials
C) Moving electric charges
D) Stationary insulators
Correct Answer: D
The content lists three things a magnetic field exerts a force on: 'moving electric charges, electric currents, or magnetic materials.' A stationary insulator is neither a moving charge, a current, nor typically a magnetic material, so it would not experience a magnetic force based on the provided definition.