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32 Cards in this Set

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voltage, V

U/Q (energy per unit charge)

Vs

Vr + Vb

Current, I [A] =

delta Q/ delta t

Current, I =

n.A.Vave.e

ohms law

R = V/I



Impedance, Z

Z = V/I

Capacitance, C

= Q/V

Reactance of capacitor, Xc

= V(t)/C(t) = 1/jwc

|reactance of capacitor|, |Xc|

= 1/wc = 1/2pifC

Voltage across inductor, VL

= L . dI/dt

impedance across inductor, ZL

= XL = jwL

Power, P

= VI = I^2R = V^2/R

rms value

= A/SQRT2

Irms

= Imax/SQRT2

Vrms

= Vmax/SQRT2

Prms

= Vrms . Irms

Energy

= P x t

Cost

kWh

kWh x running time x £ per kWh

Voltage across potential divider

V1 = R1/R1+R2 . Vs

Current divider rule

I1 = R1/R1+R2 . Is

Linear circuit

Vout = k Vin

Low pass filter - gain

G = Vout/Vin = Xc/R+Xc

Low pass filter - |gain|

|G| = 1 / SQRT(1 + (wCR)^2)

Critical frequency, fc

fc = 1 / 2.pi.RC

High pass filter - Vout,

Vout = R / R+Xc . Vin

High pass filter, gain

G = |Vout/Vin | = wCR / SQRT( 1 + (wCR)^2 )

Time Constant, tau

tau = RC

98% for time constant

= 4(tau)

Diode equation

Id = Is ( e^(qV/nkT) -1 )




Is - reverse saturation current


k - boltzmann constant


T - absolute temperature


V - applied voltage across diode


n - ideality factor ( n=1=ideal diode)


q - charge of electron

Kirchoffs Current rule (KCR)

The total current entering a node in a circuit is equal to the total current leaving that node




entering node +ve


leaving node -ve

Kirchhoffs Voltage rule (KVR)

The sum of all voltage sources and drops (sinks) around a closed circuit loop

Inductance, L

= N^2 . uo . ur A / l