sinusoidal steady state
Indicates every voltage and current in a system is sinusoidal with the same angular frequency ω.
Examples of sinusoidal steady state in the following topics:

Phasors

Driven Oscillations and Resonance

Resistors in AC Circuits

Position, Velocity, and Acceleration as a Function of Time

Spherical Accretion
 We continue looking at steady flows with two specific applications: matter flowing onto an object (accretion) and matter flowing away from an object (winds).
 We will assume that the accretion is steady at a rate ${\dot M}$ and that the pressure $P \propto \rho^\gamma$ with $1 < \gamma < 5/3$.
 Let's use the equation of state to eliminate $p$ from the Euler equation and use the continuity equation to eliminate $\rho$,

Different Types of Currents

Time

Detonation Waves
 Because the flux of the flow is conserved through the transition, the state of the gas must remain on the chord .
 There is a minimum flux that can pass through the detonation front, , and this flux also corresponds to the minimum velocity jump through the front where the final state is or the Jouguet point.
 Furthermore, for final states above $O$ along $a'$ the gas leaves the front subsonically.
 If the final state lies at $O$, the gas leaves the detonation front right at the speed of sound in the downstream flow.
 At this point the postshock gas leaves the front at the sound speed so the rarefaction wave no longer overtakes the shock and the combined detonation front and rarefaction wave achieves a steady state.

Maxwell's Equations

B.2 Chapter 2
 For the linearly polarized wave, the particle moves up and down sinusoidally.
 The velocity varies sinusoidally, the power magnetic force vary as $\sin^2 \omega t$.
 This states that the divergence of the current must vanish, which means that either charge is not conserved or that the charge density is constant (neither is good).