Unit of inductance = Henry (H)=1V·s/A

Mutual inductance: where =flux through 1 due to current in 2. Reciprocity:

Self-inductance:

**,** **,**
Stored energy=

in LR circuit where .

in LC circuit where

Unit of inductance = Henry (H)=1V·s/A

Mutual inductance: $M{\tfrac {dI_{2}}{dt}}=N_{1}{\tfrac {d\Phi _{12}}{dt}}=-\varepsilon _{1}$ where $\Phi _{12}$=flux through 1 due to current in 2. Reciprocity: $M{\tfrac {dI_{1}}{dt}}=-\varepsilon _{2}$

Self-inductance: $N\Phi _{m}=LI\rightarrow \varepsilon =-L{\tfrac {dI}{dt}}$

$L_{\text{solenoid}}\approx \mu _{0}N^{2}A\ell$**,** $L_{\text{toroid}}\approx {\tfrac {\mu _{0}N^{2}h}{2\pi }}\ln {\tfrac {R_{2}}{R_{1}}}$**,**
Stored energy=${\tfrac {1}{2}}LI^{2}$

$I(t)={\tfrac {\varepsilon }{R}}\left(1-e^{-t/\tau }\right)$ in LR circuit where $\tau =L/R$.

$q(t)=q_{0}\cos(\omega t+\phi )$ in LC circuit where $\omega ={\sqrt {\tfrac {1}{LC}}}$