Practical Electronics/Basic Theory/General Formulae

Charge

Charge refers to quantities of Electric Charge of an object

1 C = Number of Electrons e

Voltage

Voltage is defined as Work done on a Charge

$Q=\int Wdt$

Current

Current is defined as ratio of Charge over Time

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

I , Current

Q , Charge

t , Time

$1A={\frac {1C}{1s}}$

Resistance

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

R , Resistance

V , Voltage

I , Current

Conductance

$G={\frac {1}{R}}$

$G={\frac {I}{V}}$

G , Conductance

R , Resistance

I , Current

V , Volatge

Reactance

X = ± j ω T

X , Reactance

ω , Angular of Frequency

T , Time Constant

Impedance

Z = R + X

Z , Impedance

R , Resistance

X , Reactance

Power

Power Loss

P _R = I V = $I^{2}R$ = ${\frac {V^{2}}{R}}$

Power Delivered

$P=P_{V}-P_{R}=VI-I^{2}R=VI-{\frac {V^{2}}{R}}$

Power Stored

$P_{C}={\frac {1}{2}}CV^{2}$

$P_{L}={\frac {1}{2}}LI^{2}$