Foundations

Linear restoring acceleration produces sinusoidal motion.

The familiar pendulum period requires a small swing.

A wave’s pattern speed differs from the motion of its medium.

Energy transport grows with squared amplitude and frequency in the linear model.

A decibel value needs a reference and a specified measured quantity.

Slow modulation comes from superposing close frequencies.

Source and observer velocities are measured relative to the medium.

Heat is energy transferred because of a temperature difference.

Thermal size changes depend on temperature and constraints.

Boundary work depends on the process, while internal energy is a state function.

The power law needs an ideal gas and constant heat-capacity ratio.

Restoring the system alone does not establish reversibility.

Use a reversible comparison path to calculate a state-function change.

A heat pump moves heat as well as consuming work.

A collision length depends on number density and cross section.

Neutral matter can contain both positive and negative charge.

Charge mobility and polarization are different from net charging.

Equilibrium field vanishes in the conducting material, including a charged conductor.

Voltage is energy change per unit charge.

Current measures signed charge flow across a surface.

Resistance belongs to a device geometry; resistivity is a material response.

Series shares current; parallel shares voltage.

Voltage times signed current measures element power.

An emf is an energy-per-charge quantity, not a force.

Capacitor network rules differ from resistor rules.

Charging work produces electric-field energy.

Induction responds to flux change, not simply to the presence of a magnetic field.

Inductive storage and resistive loss are separate.

Field geometry follows the current distribution.

Turns change voltage and current while conserving ideal power.