# 2022 Live Review 5 | AP Physics 2 | Practicing Key Concepts in Magnetism with FRQ's

TLDRIn this AP Physics 2 live review session, Joe Mancino from Glastonbury High School focuses on magnetism, guiding students through problem-solving and essential concepts. The session covers electron spin, magnetic domains, types of magnetism, and the effects of magnetic fields on wires and charged particles. Mancino provides a quick overview of magnetism, including Oersted's discovery and the right-hand rule, before delving into problem-solving. Students learn to calculate forces on current-carrying wires, understand magnetic forces between wires, and analyze particle motion in electric and magnetic fields. The review also touches on induction, flux, and Lenz's law, with an emphasis on coherent paragraph responses and algebraic expression derivations, preparing students for the AP Physics 2 exam.

###### Takeaways

- ๐ Todayโs focus is on solving AP Physics 2 problems related to magnetism.
- ๐งฒ Overview topics include causes and types of magnetism, moving current and magnetic fields, and forces on wires and charged objects.
- ๐ Key concepts: electron spin, magnetic domains, ferromagnetism, paramagnetism, and diamagnetism.
- ๐งญ Understand Oerstedโs discovery: current-carrying wires create magnetic fields, illustrated by compass deflections.
- ๐ Learn the right-hand rule for determining the direction of magnetic fields around wires.
- ๐ Know how the magnitude of the magnetic field decreases with distance from the wire.
- โ๏ธ Calculate forces on current-carrying wires using the formula F = I L B sin(ฮธ).
- ๐ Explore the forces between parallel current-carrying wires: attractive if currents are in the same direction, repulsive if opposite.
- ๐ Understand electric and magnetic forces on moving charged particles and how to derive related algebraic expressions.
- ๐งฉ Practice solving AP Physics problems, including explaining paths of charged particles in electric and magnetic fields.
- โก๏ธ Induction concepts: charge separation in conductors, potential difference, and induced currents.
- ๐ Understand magnetic flux and Lenzโs law: changes in flux induce currents that oppose the change.
- ๐ Develop coherent paragraph-length responses for AP Physics exam questions, focusing on logical, evidence-based explanations.

###### Q & A

### What are the primary topics covered in the AP Physics 2 magnetism review session?

-The session covers causes and types of magnetism, how moving currents cause magnetic fields, how magnetic fields exert forces on wires and moving charged objects, and induction and flux.

### What is ferromagnetism and how does it differ from paramagnetism and diamagnetism?

-Ferromagnetism makes permanent magnets, paramagnetism creates temporary magnets when exposed to a magnetic field, and diamagnetism causes weak repulsion by a magnetic field.

### What did รrsted discover about current-carrying wires and magnetic fields?

-รrsted discovered that current-carrying wires create magnetic fields around them, which can be visualized using compasses placed around the wire.

### How does the right-hand rule help in determining the direction of the magnetic field around a wire?

-The right-hand rule states that if you point your thumb in the direction of the current, the direction your fingers curl around the wire indicates the magnetic field's direction.

### How does the magnetic force between two current-carrying wires behave?

-If the currents in the wires are in the same direction, the force is attractive. If the currents are in opposite directions, the force is repulsive.

### What is the formula for the magnetic force exerted on a current-carrying wire?

-The formula for the magnetic force is F = ILB sin(ฮธ), where I is the current, L is the length of the wire, B is the magnetic field, and ฮธ is the angle between the wire and the magnetic field.

### How does the motion of a positively charged particle differ in electric and magnetic fields?

-In an electric field, the particle's path curves in the direction of the field. In a magnetic field, the force is perpendicular to the velocity, causing circular motion.

### What is Lenz's Law and how does it relate to induced currents?

-Lenz's Law states that the direction of the induced current opposes the change in magnetic flux that caused it. This helps determine the direction of the induced current.

### How can you determine if a particle is negatively charged based on its motion in a magnetic field?

-Using the right-hand rule, if the observed motion contradicts the expected direction for a positive charge, the particle is negatively charged.

### What does the phrase 'derive an algebraic expression' mean in the context of physics problems?

-It means starting with known equations and principles from the physics curriculum and manipulating them mathematically to form a new equation that solves the problem.

###### Outlines

##### ๐ Introduction to AP Physics 2 Magnetism Review

The video script opens with an introduction to a five-day AP Physics 2 live review session, focusing on magnetism. The instructor, Joe Mancino, provides a brief overview of magnetism concepts, including the causes and types of magnetism, how moving currents generate magnetic fields, and the effects of these fields on wires and charged objects. The session aims to solve problems from the AP Physics 2 exam, covering forces on moving charges, deriving algebraic expressions for induced current, and discussing magnetic domains and their alignment. Reference is made to previous AP Daily videos for further information on these topics.

##### ๐งฒ Understanding Magnetic Fields and Forces

This paragraph delves into the specifics of magnetic fields, particularly around a current-carrying wire. It explains the relationship between current, the magnetic permeability constant (mu naught), and the inverse relationship with distance from the wire. The script references the right-hand rule for determining the direction of the magnetic field and emphasizes the importance of understanding the shape and magnitude of this field. It also covers how to calculate forces on current-carrying wires in a magnetic field, including the interaction between two wires and the Newton's third law implications.

##### ๐ Forces on Moving Charged Particles in Electric and Magnetic Fields

The script discusses the effects of electric and magnetic fields on moving charged particles. It describes the path of a positively charged particle in a downward electric field and contrasts it with its behavior in a magnetic field. The particle's trajectory is influenced by the forces exerted by the fields, resulting in different paths. The electric force is always in the direction of the field, causing a straight-line path, whereas the magnetic force causes circular motion due to its perpendicularity to both the velocity of the particle and the magnetic field.

##### ๐ฌ Analyzing Particle Trajectories in Combined Electric and Magnetic Fields

This section explores the behavior of a beam of protons moving through a region containing both an electric field and a magnetic field. The script explains how the protons are affected differently by the forces due to their varying velocities. It uses the principles of physics to argue that slower protons exit at one point, while faster ones exit at another due to the varying magnitudes of the magnetic force they experience. The explanation relies on the understanding that electric force is independent of velocity, whereas magnetic force is velocity-dependent.

##### ๐ Examining Undeflected Particle Motion Through Electric and Magnetic Fields

The script presents a scenario where a particle with an unknown charge and mass moves through an area between two charged plates and a magnetic field without deflection. It details the process of determining the charge on the particle by analyzing the forces acting on it and the conditions under which it moves with a constant velocity. The explanation involves identifying the direction of the electric field, the forces exerted by both fields, and using the right-hand rule to deduce the charge of the particle.

##### ๐ Deriving Potential Difference and Particle Mass in a Magnetic Field

This paragraph focuses on deriving algebraic expressions for the potential difference and mass of particles moving through a magnetic field. It provides a step-by-step approach to calculating the potential difference using the electric field, separation distance, and the relationship between electric and magnetic forces. Additionally, it shows how to derive an expression for the mass of a particle undergoing circular motion in a magnetic field, incorporating the concepts of centripetal acceleration and Newton's second law.

##### ๐ Exploring Particle Separation in Overlapping Fields and Induction Concepts

The script discusses an experiment involving ionized carbon atoms moving through overlapping electric and magnetic fields. It explains how particles with the same charge and speed can move in a straight line through both fields if the conditions are right. It also covers the concept of particle separation based on mass in a magnetic field, where heavier particles like carbon-14 have a wider radius of curvature. The explanation includes the principles of induction, such as charge separation in a magnetic field, the potential difference (emf), and the factors affecting it.

##### ๐ Understanding Induction and Magnetic Flux

This section provides a review of induction concepts, including the definition of magnetic flux and Lenz's law. It explains how a changing magnetic flux through a loop induces an electromotive force (emf) and how this induced current creates its own flux to oppose the change. The script also covers the relationship between the motion of a conducting rod in a magnetic field and the resulting current, as well as the factors influencing the magnitude and direction of the induced current.

##### ๐ Practicing Induction with a Moving Rectangular Loop

The script presents a problem involving a rectangular conducting loop moving at a constant speed into a magnetic field. It asks for a comparison of the magnitude and direction of the induced current at different times. The explanation involves understanding when and why current is induced, referencing the changing magnetic flux through the loop. The response requires using fundamental physics concepts and principles, such as Lenz's law and the forces on charge carriers, to explain the presence and direction of the current.

##### ๐ Conclusion and Final Thoughts on AP Physics 2 Preparation

In conclusion, the script emphasizes the importance of understanding the forces on moving charged objects, writing paragraph-length responses, deriving algebraic expressions, and analyzing the magnitude and direction of induced current. It encourages students to review the material, particularly the concept of flux, and to check out additional resources for a deeper understanding. The instructor wishes the students luck for their upcoming AP Physics 2 exam and looks forward to future sessions.

###### Mindmap

###### Keywords

##### ๐กMagnetism

##### ๐กMagnetic Field

##### ๐กFerromagnetism

##### ๐กParamagnetism

##### ๐กDiamagnetism

##### ๐กOersted's Discovery

##### ๐กRight-Hand Rule

##### ๐กMagnetic Force

##### ๐กInduced Current

##### ๐กFlux

##### ๐กParagraph-Length Responses

###### Highlights

Day five of AP Daily focuses on magnetism, solving problems from the AP Physics 2 exam.

Quick overview of magnetism concepts: causes, types, and effects of magnetic fields.

Explanation of how moving current causes a magnetic field, referencing รrsted's discovery.

The right-hand rule for determining the direction of the magnetic field around a wire.

Decrease in magnetic field magnitude with distance from the wire.

Differentiating between ferromagnetism, paramagnetism, and diamagnetism.

Understanding forces exerted on current-carrying wires in a magnetic field.

Newton's third law and the relationship between forces on two current-carrying wires.

Calculating the effects of electric and magnetic forces on moving charged particles.

The impact of electric fields on the trajectory of a positively charged particle.

Circular motion of particles in a magnetic field due to perpendicular forces.

Combining electric and magnetic fields to analyze the paths of protons.

Writing coherent paragraph-length responses to explain physics phenomena.

Deriving algebraic expressions for potential difference and particle mass.

Practical application of physics concepts to separate carbon isotopes using electric and magnetic fields.

Fundamentals of electromagnetic induction, including induced EMF and current.

Analyzing the magnitude and direction of induced current in a conducting loop moving through a magnetic field.

Lenz's law and its application in determining the direction of induced current.

Flux and its role in inducing current when there is a change in the magnetic field through a loop.

Comparing current magnitude and direction at different times using Faraday's law of electromagnetic induction.

###### Transcripts

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