AP Physics 2 Quiz: Magnetism And Current Carrying Wires

What this quiz covers

This quiz focuses on Magnetism And Current Carrying Wires, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Physics 2.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. The force is in the $+z$ direction. (correct answer)
2. The force is in the $+y$ direction.
3. The force is in the $-x$ direction.
4. The force is in the $-z$ direction.

Explanation: This problem tests magnetism and current-carrying wires. The wire carries current in the +x direction (to the right), and the magnetic field points in the +y direction. To find the force direction, we use the right-hand rule: point fingers in the direction of current (+x), curl them toward the magnetic field (+y), and the thumb points in the force direction. Following this rule, the force points in the +z direction (out of the page). Choice C incorrectly suggests the force is in the -x direction, which represents the misconception that the force opposes the current direction. Remember to always use the right-hand rule systematically: current direction first, then curl toward the field.

Question 2

1. It is directed to the right along $\vec{B}$.
2. It is directed into the page.
3. It is directed upward on the page.
4. It is directed downward on the page. (correct answer)

Explanation: This problem tests understanding of magnetism and current-carrying wires. When current flows into the page through a rightward-pointing magnetic field, we find the force using the right-hand rule. Point your fingers into the page (current direction) and curl them to the right (field direction) - your thumb points downward on the page. Choice D incorrectly suggests the force follows the magnetic field direction, demonstrating the misconception that forces align with fields rather than being perpendicular. Remember to visualize the three-dimensional nature of the problem and apply the right-hand rule carefully to find the perpendicular force direction.

Question 3

1. They repel each other.
2. They are pushed upward along their lengths.
3. They attract each other. (correct answer)
4. They experience no magnetic force.

Explanation: This problem tests magnetism and current-carrying wires. Two parallel wires carry currents in the same direction (both 5.0 A upward), creating magnetic fields that interact. The right-hand rule shows that wire 1 creates a magnetic field circling it, which at wire 2's location points perpendicular to wire 2. Applying the force rule to wire 2 in wire 1's field shows the force points toward wire 1. By Newton's third law, parallel currents attract each other. Choice A (repel) reflects the misconception that like currents repel, confusing this with electric charges. Remember: parallel currents in the same direction always attract, while antiparallel currents repel.

Question 4

1. They experience no magnetic force.
2. They repel each other.
3. They attract each other. (correct answer)
4. They experience forces along their lengths.

Explanation: This problem tests magnetism and current-carrying wires. Parallel wires carrying currents in the same direction attract each other due to the magnetic interaction between them. Each wire creates a circular magnetic field, and when both currents flow upward, the field from one wire at the location of the other creates an attractive force. This follows from the fundamental principle that parallel currents attract while antiparallel currents repel. Choice A incorrectly reverses this rule, possibly confusing same-direction currents with opposite-direction currents. Remember this key principle: like currents attract, unlike currents repel - opposite to electric charges.

Question 5

1. It is upward, away from the bottom wire. (correct answer)
2. It is east, along the direction of current.
3. It is downward, toward the bottom wire.
4. It is west, opposite the direction of current.

Explanation: This problem tests magnetism and current-carrying wires. The top wire carries current east while the bottom wire carries current west, making them antiparallel. Using the right-hand rule, the bottom wire creates a magnetic field that circles it; at the top wire's location, this field points into the page. Applying F = IL × B to the top wire (current east, field into page) gives a force pointing upward, away from the bottom wire. Choice B (downward) represents the attraction misconception, forgetting that antiparallel currents repel. To avoid errors, always determine the magnetic field at one wire's location due to the other wire first.

Question 6

1. They attract each other.
2. They repel each other. (correct answer)
3. They are pushed upward along their lengths.
4. They experience no magnetic force.

Explanation: This problem tests magnetism and current-carrying wires. The left wire carries current upward while the right wire carries current downward, making them antiparallel. Using the right-hand rule, each wire creates a circular magnetic field; at the other wire's location, these fields cause forces that push the wires apart. Antiparallel currents always repel each other, opposite to the attraction of parallel currents. Choice A (attract) represents confusing antiparallel with parallel currents, a fundamental conceptual error. Remember the simple rule: currents in the same direction attract, currents in opposite directions repel.

Question 7

1. move to the right together because the force is along the wires.
2. attract each other because the currents are in the same direction. (correct answer)
3. experience no force because the currents are parallel.
4. repel each other because the currents are equal.

Explanation: This problem tests understanding of magnetism and current-carrying wires. When parallel wires carry current in the same direction, they attract each other due to the interaction between each wire's magnetic field and the other's current. The top wire creates a magnetic field that circles it - at the bottom wire's location, this field points into the page. Applying the right-hand rule to the bottom wire (current right, field into page), the force points upward toward the top wire. Choice A incorrectly suggests equal currents cause repulsion, missing that force direction depends on relative current directions, not magnitudes. Remember: parallel currents in the same direction attract, opposite directions repel.

Question 8

1. The force is in the -y direction.
2. The force is into the page.
3. The force is in the +x direction.
4. The force is in the +y direction. (correct answer)

Explanation: This problem tests magnetism and current-carrying wires. The wire carries current along +x (to the right), and the magnetic field points into the page (-z direction). Using the right-hand rule: point fingers right (+x), curl them into the page (-z), and the thumb points upward (+y). The force is in the +y direction. Choice B incorrectly suggests the force is into the page, confusing the field direction with the force direction. Always apply the right-hand rule systematically to find the force as the cross product of current and field.

Question 9

1. The force is downward.
2. The force is to the right.
3. The force is to the left. (correct answer)
4. The force is out of the page.

Explanation: This problem tests magnetism and current-carrying wires. A vertical wire with downward current in a magnetic field out of the page experiences a force found by the right-hand rule: point fingers down (current) and curl them out of the page (field) - your thumb points left, indicating the force direction. The force is perpendicular to both the current and magnetic field, following F = IL × B. The downward current interacts with the outward field to produce a leftward force. Choice A reverses the force direction, a common error when confusing the right-hand rule steps. Practice the right-hand rule with clear finger positions: straight fingers for current, curl for field, thumb for force.

Question 10

1. It is directed upward on the page.
2. It is directed downward on the page. (correct answer)
3. It is directed into the page.
4. It is directed to the left along the wire.

Explanation: This problem tests understanding of magnetism and current-carrying wires. With current flowing left and magnetic field into the page, we apply the right-hand rule to find the force direction. Point your fingers to the left (current direction) and curl them into the page (field direction) - your thumb points downward on the page, indicating the force direction. Choice D incorrectly assumes the force follows the field direction into the page, demonstrating confusion about the perpendicular nature of magnetic forces. Always use the right-hand rule systematically: the magnetic force is perpendicular to both current and field directions.

Question 11

1. It points to the left. (correct answer)
2. It points upward.
3. It points to the right.
4. It points out of the page.

Explanation: This problem tests magnetism and current-carrying wires. The current points out of the page while the magnetic field points upward. Using the right-hand rule, point fingers out of the page (current) and curl them upward (field); your thumb points to the left. The magnetic force is always perpendicular to both current and field vectors. Choice A (right) represents applying the right-hand rule backward, a common error when dealing with out-of-page directions. To avoid mistakes with 3D problems, physically orient your hand to match the geometry before applying the rule.

Question 12

1. The force is upward along the wire.
2. The force is to the left.
3. The force is into the page.
4. The force is to the right. (correct answer)

Explanation: This problem tests magnetism and current-carrying wires. The wire carries current upward (vertical), and the magnetic field points into the page. Using the right-hand rule: point fingers upward (current direction), curl them into the page (field direction), and the thumb points to the right. Therefore, the magnetic force on the wire segment is to the right. Choice C incorrectly suggests the force is into the page, which represents the misconception of confusing the field direction with the force direction. Always apply the right-hand rule carefully: fingers along current, curl toward field, thumb shows force.

Question 13

1. It is directed out of the page.
2. It is directed to the left along the wire.
3. It is directed upward in the direction of $\vec{B}$.
4. It is directed into the page. (correct answer)

Explanation: This problem tests understanding of magnetism and current-carrying wires. When current flows to the left through an upward-pointing magnetic field, we apply the right-hand rule to find the force direction. Point your fingers left (current direction) and curl them upward (field direction) - your thumb points into the page, indicating the force direction. Choice D incorrectly assumes the force follows the magnetic field direction, a fundamental misconception about how magnetic forces work perpendicular to both current and field. Use the right-hand rule systematically: fingers along current, curl toward field, thumb shows force - the force is always perpendicular to both.

Question 14

1. It is directed into the page.
2. It is directed downward on the page.
3. It is directed to the right along the wire.
4. It is directed upward on the page. (correct answer)

Explanation: This problem tests understanding of magnetism and current-carrying wires. When a current-carrying wire is placed in a magnetic field, it experiences a force given by F = IL × B, where the direction is determined by the right-hand rule. With current flowing to the right and magnetic field into the page, point your fingers right (current direction) and curl them into the page (field direction) - your thumb points upward, indicating the force direction. Choice C incorrectly assumes the force follows the field direction, a common misconception that magnetic force acts parallel to the magnetic field. Remember to use the right-hand rule: fingers point along current, curl toward field, thumb shows force direction.

Question 15

1. It is directed downward on the page.
2. It is directed upward on the page. (correct answer)
3. It is directed out of the page.
4. It is directed to the right along the second wire.

Explanation: This problem tests understanding of magnetism and current-carrying wires. A wire carrying current upward creates a circular magnetic field around it - using the right-hand rule, if the field is into the page to the right of the wire, this confirms the upward current direction. For the second wire carrying current to the right in this field (into the page), apply the right-hand rule: fingers right (current), curl into page (field), thumb points upward (force). Choice B incorrectly assumes forces act along the wire direction, confusing magnetic force with tension or other longitudinal forces. Always determine the magnetic field first, then apply the force rule to find the perpendicular force direction.

Question 16

1. It is upward along the wire.
2. It is zero because the currents are equal.
3. It is away from the right wire.
4. It is toward the right wire. (correct answer)

Explanation: This problem tests magnetism and current-carrying wires. When two parallel wires carry currents in the same direction (both upward), they attract each other, so the left wire experiences a force toward the right wire. The right wire's upward current creates a circular magnetic field that, at the left wire's position, points into the page, causing the left wire's upward current to experience a rightward force. This attractive force between parallel currents is a fundamental electromagnetic principle. Choice D incorrectly assumes equal currents produce no force, confusing force balance with force existence. Remember: parallel currents always attract regardless of their magnitudes.

Question 17

1. The force is to the right.
2. The force is upward. (correct answer)
3. The force is downward.
4. The force is into the page.

Explanation: This problem tests magnetism and current-carrying wires. When a current-carrying wire is placed in a magnetic field, it experiences a force given by F = IL × B, where the direction follows the right-hand rule. With current flowing right and magnetic field into the page, point your fingers right (current direction) and curl them into the page (field direction) - your thumb points upward, indicating the force direction. The force is perpendicular to both the current and magnetic field directions. Choice C incorrectly assumes the force aligns with the field, a common misconception that magnetic forces act parallel to magnetic fields. To solve such problems systematically, first identify the current and field directions, then apply the right-hand rule to find the force direction.

Question 18

1. It points upward. (correct answer)
2. It points north.
3. It points east.
4. It points south.

Explanation: This problem tests magnetism and current-carrying wires. The wire carries current east (I = 3.0 A) in a magnetic field pointing north (B = 0.20 T). Using the right-hand rule, point your fingers east (current direction) and curl them toward north (field direction); your thumb points upward, indicating the force direction. The force magnitude is F = ILB sin(θ), where θ = 90° between current and field. Choice B (south) represents reversing the field direction, a common error when students confuse geographic directions. To solve such problems systematically, always identify the current direction first, then the field direction, and apply the right-hand rule carefully.

Question 19

1. The force is upward.
2. The force is downward.
3. The force is zero. (correct answer)
4. The force is into the page.

Explanation: This problem tests magnetism and current-carrying wires. When current and magnetic field are parallel (both pointing right), the magnetic force is zero because F = IL × B and the cross product of parallel vectors is zero. This is a fundamental property: magnetic forces only exist when current and field have some perpendicular component. No amount of current or field strength can create a force when they're perfectly aligned. Choice A incorrectly assumes any current in a field experiences force, missing the crucial role of relative orientation. Always check if current and field are parallel before calculating forces - this saves time and prevents errors.

Question 20

1. It points east.
2. It points south.
3. It points north. (correct answer)
4. It points downward.

Explanation: This problem tests magnetism and current-carrying wires. The wire carries current downward (vertical) in an eastward magnetic field (horizontal). Using the right-hand rule, point fingers downward (current) and curl them east (field); your thumb points north. The force is horizontal and perpendicular to both the vertical current and horizontal field. Choice C (downward) incorrectly assumes force aligns with current, forgetting that magnetic force must be perpendicular to both I and B. When current and field are perpendicular, the force direction completes a right-handed coordinate system with them.