Electromagnetic Damping

Core Sentence / 核心句

Electromagnetic damping converts mechanical energy into electrical energy by inducing a current whose magnetic force opposes motion.

中文理解：运动产生 EMF 和 current，current 在 magnetic field 中又受到反向 force，因此 kinetic energy 被转移到 circuit。

sliding rod：

F_{B} = \frac{B ^{2} L ^{2}}{R} v

direction opposite motion。

m \frac{d v}{d t} = - \frac{B ^{2} L ^{2}}{R} v

v (t) = v_{0} e^{- t / τ}

τ = \frac{m R}{B ^{2} L ^{2}}

m g - \frac{B ^{2} L ^{2}}{R} v = m \frac{d v}{d t}

v_{t} = \frac{m g R}{B ^{2} L ^{2}}

constant speed：

F_{ext} v = E I = I^{2} R