Electricity/Direct current

Direct current

Source of electricity that provides constant voltage over time

${\displaystyle v(t)=V}$

o---[- +]---o

DC and conductor

Resistor

Voltage by Ohm's law

${\displaystyle V=IR}$

Current

${\displaystyle I={\frac {V}{R}}}$

Resistance

${\displaystyle R={\frac {V}{I}}=\rho {\frac {l}{A}}}$

Conductance

${\displaystyle G={\frac {I}{V}}={\frac {1}{R}}={\frac {1}{\rho }}{\frac {A}{l}}=\sigma {\frac {A}{l}}}$

Power generated

${\displaystyle P_{V}=IV}$

Power loss . Power is dissipated as heat

${\displaystyle P_{V}=IR(T)}$
${\displaystyle R(T)=R_{o}+nT}$
${\displaystyle R(T)=R_{o}e^{nT}}$

Power transmitted

${\displaystyle P=P_{V}-P_{R}}$

Capacitor

Charge

${\displaystyle Q=CV}$

Capacitance

${\displaystyle C={\frac {Q}{V}}}$

Voltage

${\displaystyle V={\frac {Q}{C}}={\frac {W}{Q}}}$

Current

${\displaystyle I={\frac {Q}{t}}}$

Power

${\displaystyle P={\frac {W}{t}}={\frac {W}{Q}}{\frac {Q}{t}}=VI}$

Electric field

${\displaystyle E={\frac {V}{d}}}$

Inductor

Magnetic field intensity

${\displaystyle B=LI}$

Inductance

${\displaystyle L={\frac {B}{I}}}$

Current

${\displaystyle I={\frac {B}{L}}}$