問題一覧
1
flow of electricity PERIODICALLY REVERSES IN DIRECTION
Alternating Current
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FORMULA: Frequency
F = 1/T
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It is how high the sin wave in ac
AMPLITUDE
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Time to complete one cycle
Period
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It is when waveform repeats
CYCLE
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Cycles = Frequency
60 Cycles = 60 Hertz
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1 cycle = 2 alternations
x2
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FORMULA: Wavelength
lambda = Vp/f Vp = C x Vf c= 3x10^8
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C = Speed of light
3x10^8 m/s2 speed of light
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a flow of electricity which reaches maximum in one direction, decreases to zero, then reverses itself and reaches maximum in the opposite direction
Alternating Current
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The maximum value of a waveform of one alternation either negative or positive alternation
Maximum Value Peak Value
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FORMULA WAVELENGTH
lambda = Vp/c Vp = Vf x c c = 3x10^8 m/s2
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the instantaneous value of voltage or current is the value or current at one particular instant
Instantaneous Value
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FORMULA INSTANTANOUS VALUE
V(o) = Vm sin(O) V(t) = Vm x sin (2pift) V(w) = Vm x sin (wt)
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the average of the ALL the Instantaneous values for a certain period of time
Average Value
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FORMULA: AVERAGE Value/ Dc Value/ Mean Value
.636Vm
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value that will have the same heating effect on a resistance as a comparable value of direct current or voltage will have on the same r e s i s t a n c e
Vrms/ Effective Value/ Ac Value
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FORMULA: Vrms
Vrms = Vm/sqrt2 = .707Vm
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the ratio of the RMS value to the AVERAGE value of an alternating quantity
FORM FACTOR
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the ratio of MAXIMUM value to the R.M.S value of an alternating quantity
PEAK FACTOR/ CREST FACTOR/ AMPLITUDE FACTOR
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opposition to current offered by resistive components
Resistance
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reciprocal of resistance
CONDUCTANCE G
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FORMULA CONDUCTANCE
G= 1/R
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opposition offered by inductor and capacitor to AC
REACTANCE X
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FORMULA REACTANCE
XL = 2pifL Xc = 1/2pifc
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reciprocal of reactance
SUSCEPTANCE B
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total opposition to the flow of AC combination of resistance and reactance
IMPEDANCE Z
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FORMULA IMPEDANCE
Z= sqrt R^2 + X^2 R+-Xlc
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reciprocal of impedance combination of conductance and susceptance
ADMITTANCE Y
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V and I are in phaseV and I are in phase
PURELY RESISTIVE
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the current lags the applied voltage by 90°
Purely Inductive Circuit
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the current leads the voltage by 90°
Purely Capacitive Circuit
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the current lags the applied voltage by an angle greater than 0° but less than 90°
Inductive Circuit
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the current leads the applied voltage by an angle greater than 0° but less than 90°
Capacitive Circuit
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the power consumed or dissipated by the resistive component also called True Power, Useful Power and Productive Power measured in Watts (W) it is equal to the product of the apparent power and the power factor
REAL POWER/ TRUE POWER
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FORMULA REAL POWER
P= VIcos(0)= VIpf P= Pf x S P= I^2 x R
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represents the rate at which energy is stored or released in the reactive component also called the imaginary power, non- productive or wattless power It is positive for inductive power (Q) and negative for capacitive power (Qc) measured in volt ampere reactive VAR
REACTIVE POWER Q
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FORMULA REACTIVE POWER
Q= VIsin(0) = VI x rf Q= I2Xlc Q= rf x S
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represents the rate at which the total energy is supplied to the system measured in volt-amperes (VA) the vector sum of the true and reactive powers
APPARENT POWER
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FORMULA APPARENT POWER
S = sqrt P^2+Q^2 S = I^2 Z
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FORMULA: POWER FACTOR p.f
Pf = P/S
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FORMULA: REACTIVE FACTOR r.f
rf = Q/S
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a circuit phenomenon or condition wherein: the current is in phase with the voltage • the circuit power factor becomes unity the inductive reactance is equal to capacitive reactance
Resonance
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at resonance or at f = fr → XC=XL below resonance or at f<fr → XC>XL above resonance or at f>fr → XL>XC
q
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consists of a coil and a capacitor connected in series or in parallel
TUNED OR RESONANT CIRCUIT
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6 C h a r a c t e r i s t i c s o f S e r i e s R e s o n a n c e
At f=fr, XL=Xc, and since series connected components have same current, VL=Vc At f=fr, Z is minimum (Z=R) At f=fr, I is maximum (I=E/R) At f=fr, Z is resistive (I is in-phase with E) At f<fr, Z is capacitive At f>fr, Z is inductive
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FORMULA RESONANCE
fr = 1/2pi sqrt LC
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FORMULA QUALITY FACTOR
q
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FORMULA RESONANT RISE IN REACTIVE VOLTAGE:
Vc or VL = Q x Vs
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6 Characteristics of Parallel R e s o n a n c e
At f=fr, XL=Xc, and since parallel branches have same voltage, IL=lc At f=fr, Z is maximum (Z=R₽) At f=fr, I is minimum (I=E/Rp) At f=fr, Z is resistive (I-is in-phase with E) At fsfr, Z is inductive At f>fr, Z is capacitive
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FORMULA RESONANCE PARALLEL
fr = 1/2pi sqrt LC
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FORMULA Q FACTOR PARALLEL
X/rs + X^2/Rp
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FORMULA RESONANT RISE IN TANK CURRENT:
Ic or IL = Q x Is
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in series resonant circuit, Q is also called as the
VOLTAGE MAGNIFICATION FACTOR
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FORMULA PEAK TO PEAK VALUE
Vpp = 2Vm
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in a parallel resonant circuit, Q is also called as
CURRENT MAGNIFICATION FACTOR
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parallel resonance is also called
Anti Resonance
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parameter that indicates the width of frequencies centered around the resonant frequency RANGE of frequencies included between the two cut-off frequencies
Bandwidth
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cut-off points are the points wherein
-the current drops to 70.7% of its max v a l u e - the voltage drops to 70.7% of its max value - the power drops to 50% of its max
60
cut-off points are also called
HALF-POWER, CUT-OFF, BREAK-OFF, and 3 dB DOWN Points
61
FORMULA 3PHASE AC LINE
q
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FORMULA : BANDWIDTH
fr = Q x Bw
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FORMULA UPPER AND LOWER CUT OFF FREQ
fu = fr + BW/2
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a circuit consisting of a combination of capacitors, inductors and resistors connected so that it wil either PERMIT OR PREVENT passage of a certain band of frequencies
PASSIVE FILTERS
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- passes all signals having frequencies lower than its cut-off frequency
LOW PASS FILTERS
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passes all signals having frequencies higher than its cut-off frequency
HIGH PASS FILTERS
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passes frequencies within a certain range and rejects (attenuates) frequencies outside that range
BANDPASS FILTERS
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rejects or blocks all signals having frequencies between the two cut-off frequencies
BAND REJECT FILTERS
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also known as band-elimination, band-stop, or notch filters
BAND REJECT FILTERS
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FORMULA CUT OFF FREQUENCY
1/2pift t time constant
71
FORMULA CENTER RESONANT FREQ
fr = sqrt fl x fu
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It is a quantity that varies in MAGNITUDE AND DIRECTION with respect to time
ALTERNATING QUANTITY
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the NUMBER OF CYCLES in ONE SECOND
FREQUENCY
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the LENGTH OF TIME it takes to COMPLETE ON CYCLE
PERIOD
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is the DISTANCE BETWEEN TWO POINTS OF SIMILAR CYCLES of a periodic wave
WAVELENGTH
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the VALUE OF THE WAVE AT ITS PEAK
AMPLITUDE