PHY 1020 – Electricity and Magnetism (Chapter 6)

Vocabulary flashcards covering the main concepts, terms, and phenomena discussed in the PHY 1020 lecture on electricity and magnetism.

Fundamental Forces

The four basic interactions in nature: strong, electromagnetic, weak, and gravitational.

Strong Interaction

Force that binds nucleons in an atomic nucleus; mediated by gluons; strongest but very short-range (~10⁻¹⁵ m).

Electromagnetic Interaction

Infinite-range force between electric charges; mediated by photons; relative strength = 1.

Weak Interaction

Short-range (~10⁻¹⁸ m) force responsible for β-decay; mediated by W⁺, W⁻, and Z⁰ bosons.

Gravitational Interaction

Attractive force between masses/energy; weakest (≈10⁻⁴¹ of EM) yet infinite in range; hypothetically mediated by gravitons.

Electric Charge

Fundamental property of matter producing electromagnetic forces; exists as positive or negative and is conserved.

Charge Conservation

The total electric charge in an isolated system remains constant over time.

Quantization of Charge

Charge occurs in discrete multiples of the elementary charge e = 1.6 × 10⁻¹⁹ C.

Coulomb (C)

SI unit of electric charge; 1 C equals the charge transported by 1 A of current in 1 s.

Permittivity of Free Space (ε₀)

Physical constant 8.854 × 10⁻¹² F / m governing electric field strength in vacuum.

Static Electricity

High-voltage (1 kV–100 kV) discharge with very small current (~1 mA), producing negligible power.

Electric Current (I)

Rate of charge flow; measured in amperes (1 A = 1 C / s).

Voltage (Electric Potential)

Energy per unit charge; 1 V = 1 J / C and gives the “push” for current.

Electrical Resistance (R)

Opposition to current flow in a material; R = V / I, measured in ohms (Ω).

Electric Power (P)

Rate of electrical energy transfer; P = VI or P = I²R.

Household Supply (U.S.)

Standard service of 110 V up to about 100 A, giving a maximum power of ≈11 kW.

Alternating Current (AC)

Electric current that periodically reverses direction; efficient for high-voltage transmission.

Direct Current (DC)

Electric current flowing in a single, constant direction; common in batteries.

War of Currents

Late-19th-century rivalry between Edison’s DC system and Tesla’s AC system—AC ultimately prevailed.

Fuse

Safety device that melts to open a circuit when current exceeds a preset value, preventing damage.

Circuit Breaker

Resettable switch that disconnects power when excessive current is detected.

Electric Grid

Interconnected network for delivering electricity, divided in the U.S. into East, West, and Texas regions.

I²R Power Loss

Energy dissipated as heat in transmission lines: P_loss = I²R; motivates high-voltage, low-current transmission.

Lightning

Natural discharge of ~10 MV and ~100 kA, releasing about 10¹² W of power momentarily.

Magnetism

Phenomenon produced by moving charges or intrinsic electron spin, yielding magnetic fields with north and south poles.

Ferromagnet

Material with permanently aligned magnetic domains, producing a strong, persistent magnetic field.

Curie Temperature

Temperature above which a ferromagnetic material loses its permanent magnetism.

Magnetic Monopole

Hypothetical isolated north or south magnetic charge; never observed in nature so far.

Electromagnet

Magnet created by electric current flowing through a coil of wire; field strength controllable via current.

Rare-Earth Magnet

Very strong permanent magnet made from rare-earth elements owing to many unpaired electrons (e.g., NdFeB).

Earth’s Magnetic Field

Planet-scale field generated by molten iron currents; shields Earth from solar charged particles.

Transformer

Device using electromagnetic induction to step voltage up or down; Vs/Vp = Ns/Np.

Electric Motor

Machine that converts electrical energy into mechanical work via torque on current-carrying coils in a magnetic field.

Electric Generator (Dynamo)

Device that converts mechanical work into electrical energy; dynamos output DC, alternators output AC.

Magnetic Recording

Data storage method encoding bits as up or down magnetic domains on media like tapes or disks.

Eddy Currents

Circulating currents induced in conductors by changing magnetic fields, often causing drag or heating.

Superconductor

Material that exhibits zero electrical resistance below its critical temperature (Tc).

Critical Temperature (Tc)

Temperature below which a material enters the superconducting state with zero resistance.

Magnetic Levitation (Maglev)

Suspension technique using repulsive forces between superconducting/strong magnets and conductors, enabling frictionless transport.