= Galvanometer readout of an induction pulse
{title2=$J_g\ddot\theta+b_g\dot\theta+\kappa_g\theta=K_gi$}
A small-angle <galvanometer> model combines its <moment of inertia> $J_g$, <damping> coefficient $b_g$ and restoring coefficient $\kappa_g$ with a torque per <electric current> $K_g$. The resulting <damped harmonic oscillator> responds to the current pulse through the displayed equation. Its angular deflection $\theta$ can continue after the driving <electric current> has ceased. Inferring the current's detailed time dependence requires the instrument response, rather than equating needle angle with instantaneous current. This is a generic readout model, not a calibration of Faraday's historical instrument.
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