Physics Notes - Herong's Tutorial Notes

∟Electromagnetic Fields

This chapter provides an introduction of electromagnetic fields. Topics include what is electric field and magntic field; point charge creating electric and magnetic fields; magnetic force on moving charges; magnetic dipole, moment, and torque.

What Is Electric Field

What Is Magnetic Field

What Are Magnetic Poles

Magnetic Force on Moving Charges

Magnetic Force on Wire Rod

Moving Charge Creating Magnetic Field

Biot-Savart Law for Magnetic Fields

Magnetic Fields of Current Carrying Loops

Magnetic Fields of Solenoids

What Is Magnetic Dipole and Moment

What Is Magnetic Torque

Takeaways:

• An electric field is the distribution of force potential in space on electrically charged objects. This definition can be expressed as: E = F / q.
• Coulomb's Law states that the force between 2 point charges is proportional to strengths of both charges and inversely proportional to square of their distance.
• The electric field of a point charge can be expressed as E = (q/(4πε₀))⋅(r/r³)
• A Magnetic Field is the distribution of magnetic influence in space.
• The magnetic force on a moving charge can be expressed as F = q (v x B).
• The equation of motion of a charge can be expressed as ma = qE + q (v x B).
• The magnetic force on a wire rod can be expressed as F = L (I x B).
• The magnetic field of a point charge can be expressed as B = (μ₀q/4π)⋅((v x r)/r³)
• The magnetic field of a straight wire can be expressed as B = (μ₀/2π)⋅(I/R)
• The magnetic field at the center of a wire loop can be expressed as B = (μ₀/2)⋅(I/R)
• The magnetic field at the center of a solenoid can be expressed as B = μ₀nI
• The magnetic moment is a vector that represents the strength and direction of a magnetic dipole.
• The magnetic torque represents the rotational force exerted on a magnetic dipole in a magnetic field. It can be expressed as: τ = μ × B.
• The maximum magnetic torque magnitude on a flat wire loop in a uniform magnetic field can be expressed as τ = AIB.
• The magnetic moment of a flat wire loop can be expressed as μ = AIn.

Table of Contents

 About This Book

 Introduction of Space

 Introduction of Frame of Reference

 Introduction of Time

 Introduction of Speed

 Newton's Laws of Motion

►Electromagnetic Fields

 Introduction of Light

 Speed of Light

 Introduction of Special Relativity

 Time Dilation in Special Relativity

 Length Contraction in Special Relativity

 The Relativity of Simultaneity

 Introduction of Spacetime

 Minkowski Spacetime and Diagrams

 Introduction of Hamiltonian

 Introduction of Lagrangian

 Introduction of Generalized Coordinates

 Phase Space and Phase Portrait

 Poisson Bracket Expression

 References

 Index

 Full Version in PDF/ePUB

Electromagnetic Fields - Updated in 2026, by Herong Yang