equations Flashcards by Hollee-Marie Jingree

equation for force (F)

(k x Q1 x Q2 ) / d^2

k : Coulomb`s law constant, 9×109 N·m2/C2
d : distance between charges
Q1 : charge 1
Q2 : charge 2

How well did you know this?

Not at all

Perfectly

equation for voltage (V)

W / Q

w : energy
Q : Charge

How well did you know this?

Not at all

Perfectly

equation for current (I)

Q / t

Q: Charge
t = time

How well did you know this?

Not at all

Perfectly

equation for resistance (R)

V / I

V : Voltage
I : Current

How well did you know this?

Not at all

Perfectly

Equation for power (P)

I x V OR I^2 x R OR V^2/R

I : Current
V : Voltage
R : Resistance

How well did you know this?

Not at all

Perfectly

equation for efficiency

Pout / Pin

Pout : Power output
Pin : Power Input

How well did you know this?

Not at all

Perfectly

equation for conductance (G)

1 / R

R : resistance

How well did you know this?

Not at all

Perfectly

equation for the sum of voltage drops in series circuit (kirchkoffs laws)

Vs = VR1 + VR2 + VR3…

Vs : total voltage drop
VRn : voltage across resistor n

How well did you know this?

Not at all

Perfectly

equation for the voltage divider rule

RN / ( R1 + R2 + R3..) x Vs

Vs : source voltage
RN : single chosen resistor
R1/R2/R3 : each resistor

How well did you know this?

Not at all

Perfectly

equation of total resistance in parallel circuit

1/R1 + 1/R2 … + 1/Rn

R1 = resistor 1

How well did you know this?

Not at all

Perfectly

equation for current source

Is = Vs / Rs

How well did you know this?

Not at all

Perfectly

equation for voltage source

Vs = Is x Rs

How well did you know this?

Not at all

Perfectly

equation for output current in nortons theorem (IN)

Vs / RT
SO
IN = [R2 / (R2 + R3)] x Vs

How well did you know this?

Not at all

Perfectly

equation for total resistance in nortons theorem

RT = R1 + (R2 x R3) / R2 + R3

How well did you know this?

Not at all

Perfectly

equation for frequency (f)

1 / T

T : period

How well did you know this?

Not at all

Perfectly

equation for period (T)

1/ f

f : Frequency

How well did you know this?

Not at all

Perfectly

equation for capacitance ( C)

Q / V

Q : Charge
V : Voltage

How well did you know this?

Not at all

Perfectly

equation for the energy stored in a capacitor (W)

1/2 x C x V^2

C : Capacitance
V : Voltage

How well did you know this?

Not at all

Perfectly

equation for total capacitance when connected in series (CT)

1 / ( 1/C1 + 1/C2 + 1/C3…)

How well did you know this?

Not at all

Perfectly

equation for voltage in RC circuits

vF + (vi - vF) x e ^-t/RC

vF : final voltage
vi : initial voltage
t : time
R : resistance
C : capacitance

How well did you know this?

Not at all

Perfectly

equation for capacitor voltage when charging from zero (vi =0)

vF ( 1 - e ^-t/RC)

vF : final voltage
t : time
R : resistance
C : capacitance

equation for capacitor voltage when discharging from zero
(vF =0)

vi x e ^-t/RC

vi : initial voltage
t : time
R : resistance
C : capacitance

equation for instantaneous capacitor current (i)

C x dv/dt

c : capacitance
dv/dt : derivative of v with respect to time

equation for capacitive reactance (Xc)

1 / (2 x pie x f x C )

Pie : 3.14
f : frequency
C : capacitance

equation for reactive power (Pr)

Vrms x Irms or V^2rms / Xc or I^2rms x Xc

what is the polar form for voltage

(square root V^2R + V^2C ) < -tan-1 (Vc/Vr)

equations in ohms laws for RC circuits using Z,V & I

V = I x Z I = V / Z Z = V / I

equation of true power in RC circuits ( Ptrue)

I^2 x R I : current R : resistance

equation of reactive power ( Pr)

I^2 x Xc Xc : capacitance reactive I : current

equation for apparent power (Pa)

V x I or I^2 x Z or square root (p^2true + Pr^2) V : voltage I : current Z : impendance

equation for impedance (Z)

square root [R^2 + (XL - XC)^2] R : resistance XL : inductive reactance Xc : capacitive reactance

equation for instantaneous voltage across an inductor (V)

L x di/dt L : inductance of coil di/dt : time rate change of current

equation for the energy stored in a inductor (W)

1/2 x L x I^2 L : inductance of coil I : current

equation for total inductors when connected in parallel (LT)

1 / ( 1/L1 + 1/L2 ... 1/Ln) Ln : each inductor

equation for time constant for inductors (t)

L / R L : Induction R : Resistance

general equation for current in RL circuits (i)

IF + (Ii - IF) x e^-Rt/L IF : final current Ii : initial current R: resistance t : time L : inductance of coil

equation for an increasing current in RL circuits when Ii = 0

IF (1-e^-Rt/L) IF : final current R : resistance t : time L : Inductance of coil

equation for a decreasing current in RL circuits when IF = 0

Ii x e^-Rt/L Ii : initial current R : resistance t : time L : inductance of coil

equation of inductive reactance (XL)

2 x pie x f x L f : frequency L : inductance of coil

equation for true power in inductors

(Irms)^2 x Rw Irms : instantaneous value of current Rw : winding resistance

equation for reactive power in an inductor

Vrms x Irms or (Irms)^2 x XL Vrms : instantaneous value of voltage Irms : instantaneous value of current XL : inductive reactance

equation for quality factor (Q)

XL/R or (2 x pie x f x L) / R when XL = 2nfL XL : inductive reactance R : resistance f : frequency L : inductance of coil

equation for resonant frequency (fr)

1 / [ 2 x pie x (squareroot L x C)] L : inductance of a coil C : capacitance

equation for cut off frequency in RC circuit

1 / ( 2 x pie x R x C ) R : resistance C : capacitance

equation for cut off frequency in RL circuit

1 / ( 2 x pie x (L/R) ) L : inductance of coil R : resistance

equation for output voltage in an RC circuit

[Xc / (squareroot R^2 + Xc^2) ] x Vin Xc : capacitive reactance R : resistance Vin : input voltage

equation for output voltage in RL circuit

[ R / (square root R^2 + XL^2) ] x Vin R : resistance XL : inductive reactance Vin : voltage input

equation for bandwidth

fr / Q fr : frequency resonance Q : quality factor

equation for upper cutoff point

fr + BW/2 fr : frequency resonance BW : band width

equation for lower cutoff point

fr - BW/2 fr : frequency resonance BW : band width