Electromagnetism, Electric Fields, and Electromagnetic Devices

Comprehensive vocabulary flashcards covering magnetic fields, electric fields, electromagnets, electric motors, generators, and practical electromagnetic technologies.

Magnetic Field

The area of a magnetic force around a magnet that begins at the north pole, travels outward and around to the south pole, and extends inside the magnet from the south pole to the north pole.

Magnetic Field Lines

Lines drawn with arrows to show the direction and value of a magnetic field; they never cross because the magnetic field direction is uniform at any given location.

Iron Filings

Small, needle-shaped pieces of iron that orient themselves along the magnetic field of a magnet, allowing the invisible magnetic field to be visualized.

Static Electricity

Electricity caused by the buildup and movement of electrons, responsible for effects such as shocks from touching a metal doorknob or clothes crackling when taken out of a dryer.

Electrons

Tiny subatomic particles with a negative charge whose movement produces electric currents and static electric phenomena.

Electric Field

A force field surrounding all charged particles that determines the types of attractive or repulsive forces exerted or experienced when near other charged particles.

Voltage

A measurement (in volts) of the energy that can be transferred out of the electric field if charges move; it acts as the push or pressure that electrons experience in a wire.

Electric Current

The steady flow of electrons through a complete path or closed circuit, allowing energy to transfer from the electric field to powered devices.

Close Reading Strategies

A structured five-step approach: 1. Identify the guiding question(s); 2. Read once for understanding; 3. Read a second time to highlight key ideas answering the questions; 4. Summarize key ideas in words or diagrams; 5. Jot down new questions raised by the reading.

Geographic Poles

The northernmost and southernmost points on Earth aligned with its rotational axis, around which the entire planet makes one full rotation every $24\,\text{hours}$.

Earth's Magnetic Poles

The magnetic poles of Earth that do not align perfectly with the rotational axis; the magnetic south pole is located near the geographic North Pole (attracting the north pole of a compass needle), while the magnetic north pole is located near the geographic South Pole.

Electromagnet

A temporary magnet created when an electric current runs through a wire coiled around a magnetic object, generating a magnetic field only while the circuit is closed.

Factors Affecting Electromagnet Strength

The two primary variables controlling an electromagnet's force: the voltage supplied by the power source (higher voltage produces a stronger current) and the number of times the wire is coiled around the core.

Magnetic Levitation (Maglev)

The state in which an object is suspended, floating, or hovering without mechanical support using magnetic forces, resulting in extremely low surface friction.

MagLev Suspension and Propulsion System

A transportation mechanism that suspends a train above the track using repulsive magnetic forces between train magnets and track electromagnets, propelling it forward up to $270\,\text{miles per hour}$ by alternating coil currents.

Electric Motor

A device that converts electrical energy into mechanical energy by using force pairs between permanent magnets and a magnetized coil of wire to spin a shaft and gears.

Electric Motor Commutation

The periodic reversal of current direction (between clockwise and counterclockwise) in an electric motor's coil, which continuously flips its magnetic poles to maintain constant rotational motion.

Generator

A device that converts mechanical energy into electrical energy by moving a magnet near a wire or rotating wire coils inside a magnetic field to create a steady flow of electrons.

Stator

A stationary cylinder consisting of a series of insulated wire coils that surrounds the rotor in an electromagnetic generator.

Rotor

An electromagnetic shaft inside an electromagnetic generator that rotates within the stator, causing an electric current to flow through each section of the surrounding wire coil.

Electromagnetic Induction

The process of generating an electric current in a conductor when it moves relative to an external magnetic field; the direction of the induced current depends on whether the magnet is moved toward or away from the coil.

Ferromagnetic Materials

Metals (such as iron and steel) that are easily magnetized temporarily and strongly attracted to a magnet, but cannot experience magnetic repulsion like permanent magnets.

Junkyard Magnet

A large crane-mounted electromagnet that uses an electric current running through a copper coil to lift heavy ferromagnetic scrap metal and releases the load as soon as the current is shut off.