Introduction to Electromagnetism

• Electromagnetism is the study of the electromagnetic force, one of the four fundamental forces in nature, and it mediates interactions between electrically charged particles
• Electric and magnetic fields are intrinsically linked within electromagnetism

Fundamental Concepts

• Electric charge causes matter to experience a force when near other charged matter
• Positive and negative are the two types of electric charges
• Like charges repel, and opposite charges attract
• An electric field is a field of force surrounding an electric charge that exerts force on other charges
• Electric potential refers to the work needed to move a unit positive charge from a reference point to a specific point inside the field
• Electric current is the rate of flow of electric charge through a conductor, measured in amperes (A)
• Magnetic field refers to a field of force created by moving electric charges (electric current) or magnetic materials that exerts a force on other moving charges and magnetic materials
• Magnetic dipole moment gauges an object's tendency to align with a magnetic field
• Electromagnetic waves encompass oscillating electric and magnetic fields propagating through space and transporting energy, like light/radio waves/X-rays

Key Laws and Principles

• Coulomb's Law quantifies the electrostatic force between two point charges
• The electrostatic force is directly proportional to the product of the magnitudes and inversely proportional to the square of the distance between them
• Gauss's Law for Electricity relates the electric field flux through a closed surface to the enclosed electric charge, and is useful for calculating electric fields in symmetric situations
• Gauss's Law for Magnetism says the magnetic flux through any closed surface is zero
• Magnetic monopoles (isolated north or south poles) do not exist
• Ampère's Law relates the magnetic field around a closed loop to the electric current through the loop, useful for calculating magnetic fields from current-carrying wires and solenoids
• Faraday's Law of Induction says changing magnetic field induces an electromotive force (EMF), which can drive an electric current in a closed circuit
• Lenz's Law states the induced current opposes the change in magnetic flux that produced it
• Maxwell's Equations consist of four equations that form the foundation of classical electromagnetism
• These equations describe how electric and magnetic fields are produced by charges and currents, and how these fields change over time and space

Electric Fields

• Electric field lines visualize electric fields via density indicating strength and direction which indicates force on a positive test charge
• Conductors in Electrostatic Equilibrium means the electric field inside a conductor is zero, excess charge resides on the surface, and electric field at the surface is perpendicular to it
• Capacitance measures a capacitor's ability to store electric charge
• Capacitance equals the ratio of charge stored to the potential difference across the capacitor

Magnetic Fields

• Magnetic field lines visualize magnetic fields via direction and density indicating field direction and strength
• The magnetic force on a moving charge is perpendicular to both the velocity and magnetic field, causing circular or helical motion
• Magnetic materials exhibit magnetic properties classified as ferromagnetic, paramagnetic, or diamagnetic based on response to external magnetic field

Electromagnetic Induction

• Motional EMF occurs in a conductor moving through a magnetic field
• Generators convert mechanical energy into electrical energy using electromagnetic induction
• Transformers increase or decrease AC voltage using electromagnetic induction, and consist of coils wound around a magnetic core

Electromagnetic Waves

• Electromagnetic waves are transverse, meaning electric/magnetic fields are perpendicular to propagation direction
• The speed of electromagnetic waves in a vacuum is constant, denoted as c, approximately 3 x 10^8 meters per second
• The electromagnetic spectrum ranges all possible frequencies of electromagnetic radiation including radio/microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays
• Poynting Vector represents energy flux (power per unit area) of an electromagnetic wave, with its direction indicating energy propagation

Applications

• Electric circuits utilize electric current flow for power distribution and electronic devices
• Electric motors convert electrical energy into mechanical energy via magnetic fields and electric currents
• Radio communication transmits information over long distances via electromagnetic waves
• Medical imaging techniques like MRI use magnetic fields and radio waves to image the human body
• Optical fibers use light (an electromagnetic wave) to transmit data over long distances with high bandwidth