Unit Overview

Magnetism and Electromagnetic Induction Overview

AP Physics 2· 5 min read 📊 10-18% of total AP Physics 2 exam score

1. Unit at a Glance

This unit builds from foundational magnetic properties to advanced induction concepts. You will first learn how magnetic fields are created by currents, then explore how magnetic fields exert forces on moving charges and wires. We then develop the core laws of electromagnetic induction before applying these concepts to real magnetic systems.

The unifying theme of this unit is the deep connection between electricity and magnetism, which underpins all modern electromagnetic technology and prepares you for the study of electromagnetic waves in later units.

All sub-topics in this unit are listed below:

AP Physics 2 Electromagnetic Induction

Introduction to the basic phenomenon of electromagnetic induction and real-world uses.

★★★⏱ 10 min

AP Physics 2 Force on Current-Carrying Wire in Magnetic Field

Calculate magnitude and direction of magnetic force on current-carrying wires.

★★⏱ 8 min

AP Physics 2 Force on Moving Charges in Magnetic Fields

Analyze magnetic forces and trajectories of moving charged particles in B-fields.

★★★⏱ 9 min

AP Physics 2 Magnetic Fields Due to Currents

Calculate magnitude and direction of B-fields produced by current-carrying conductors.

★★★⏱ 10 min

AP Physics 2 Magnetic Flux, Induced EMF, Faraday's and Lenz's Law

Master Faraday's induction law and Lenz's rule for finding induced current direction.

★★★★⏱ 12 min

AP Physics 2 Magnetic Systems

Explore practical applications including motors, generators, and transformers.

★★★⏱ 8 min

2. Common Pitfalls

Wrong move:

Confusing right-hand rules for magnetic fields vs magnetic force.

Why:

Using the wrong rule leads to consistent incorrect direction predictions.

Correct move:

Use right-hand rule with thumb along current for B-fields, thumb along velocity for force on positive charges.

Wrong move:

Ignoring the negative sign in Faraday's Law and skipping Lenz's Law analysis.

Why:

Failing to account for the opposing nature of induced current leads to wrong direction and sign errors.

Correct move:

Always identify the change in flux first, then find the direction of the induced B-field that opposes this change.

3. Quick Reference Cheatsheet

Key Concept	Formula/Rule
Force on moving charge	$F = q v B sin θ$
Force on current-carrying wire	$F = I L B sin θ$
Magnetic Flux	$Φ_{B} = B A cos θ$
Faraday's Law of Induction	$ε = - N \frac{Δ Φ _{B}}{Δ t}$
B-field from long straight wire	$B = \frac{μ _{0} I}{2 π r}$
Lenz's Law	Induced current creates a B-field that opposes the change in flux that caused it

What's Next

Begin your study of this unit with the first sub-topic on electromagnetic induction below. Once you complete all sub-topics in this unit, you can move on to the first sub-topic of the next unit on geometric optics to continue your AP Physics 2 preparation.