p.1
Phasor Diagrams Overview
What do phasor diagrams represent?
The magnitude and directional relationship between two or more alternating quantities.
p.16
Inductive Reactance and Phase Relationships
What is the reactance of an inductor called?
Inductive Reactance (X_L).
p.21
Three-Phase Phasor Systems
What components are connected in series in the described circuit?
A pure non-inductive resistance, R, and a pure inductance, L.
p.9
AC Resistance and Impedance
How is the voltage across a pure ohmic resistor related to the current flowing through it?
It is linearly proportional, as defined by Ohm’s Law.
p.15
Inductive Reactance and Phase Relationships
What is the role of an inductor in a time-varying circuit?
It acts as an impedance limiting the amount of time-varying current flowing in the coil.
p.11
AC Resistance and Impedance
How do you convert peak values to RMS values in phasor relationships?
By dividing the peak value by √2.
p.13
AC Resistance and Impedance
What laws can be used for calculating voltage, current, impedance, and power in purely resistive AC circuits?
Ohm’s Law and Kirchhoff’s Law.
p.1
Phasor Representation and Rotating Vectors
What direction is considered a positive rotation for phasors?
Anti-clockwise direction.
p.18
Inductive Reactance and Phase Relationships
What effect does increasing inductance have on inductive reactance?
Increasing inductance also increases the overall inductive reactance value.
p.23
Phase Relationships in Sinusoidal Waveforms
How is the inductive voltage represented in the vector diagram?
Line OC shows the inductive voltage, which is 90 degrees in front of the current.
p.24
AC Resistance and Impedance
What does the quantity Z represent in a circuit?
Impedance of the circuit.
p.8
Three-Phase Phasor Systems
What defines a balanced three-phase system?
The individual sinusoidal voltages have a fixed relationship of 120 degrees between each other.
p.26
Phasor Addition and Subtraction
What is the voltage drop across each component in an RL circuit?
Calculated as V_R = I * R and V_L = I * XL.
p.19
Inductive Reactance and Phase Relationships
What corresponds to the maximum voltage value of self-induced emf in an inductor?
The maximum rate of current change.
p.17
Inductive Reactance and Phase Relationships
What happens to the current when the switch is closed?
The current rises from zero to its maximum value.
p.22
Inductive Reactance and Phase Relationships
In a pure inductance circuit, how does the current relate to the voltage?
The current lags the voltage.
p.18
Inductive Reactance and Phase Relationships
What is the relationship between frequency and the rate of change of flux in an inductor?
As frequency increases, the rate of change of flux within the coil also increases.
p.21
Impedance in RL Circuits
What is meant by 'impure inductance'?
An inductive coil that has resistance in series with inductance.
p.12
AC Resistance and Impedance
What does impedance depend on in circuits with reactive components?
The frequency of the circuit (ω).
p.2
Mathematical Representation of Phasors
What does phasor notation define?
The effective (rms) magnitude of voltages and currents.
p.23
Mathematical Representation of Phasors
What does V represent in the context of the circuit?
The r.m.s value of the applied voltage.
p.24
AC Resistance and Impedance
What is impedance in an AC circuit?
The total opposition to current, consisting of resistance and reactance.
p.5
Phasor Addition and Subtraction
What is the analytical method for adding two voltages?
Finding their vertical and horizontal components to calculate the resultant 'r vector', VT.
p.6
Mathematical Representation of Phasors
How is the magnitude of voltage VT determined?
Using Pythagoras’s Theorem.
p.18
Inductive Reactance and Phase Relationships
How does the current behave when a 100Hz supply is applied to the same inductor?
The current is still delayed by 90 degrees but reaches a lower maximum value due to reduced time to peak.
p.11
Phasor Representation and Rotating Vectors
What does a phasor represent compared to a vector?
A phasor represents RMS values, while a vector represents peak values.
p.27
Phase Relationships in Sinusoidal Waveforms
What is the significance of the phase angle in AC circuits?
It indicates the time difference between the current and voltage waveforms.
p.7
Phasor Addition and Subtraction
How does phasor subtraction compare to phasor addition?
Phasor subtraction involves taking away the vector components instead of adding them.
p.1
Phasor Representation and Rotating Vectors
How are phasors defined in relation to a reference phasor?
Phasors are defined relative to a reference phasor that always points to the right along the x-axis.
p.7
Three-Phase Phasor Systems
What is generated when three identical coils are placed at an electrical angle of 120 degrees to each other?
A three-phase voltage supply.
p.10
Phase Relationships in Sinusoidal Waveforms
What is the phase difference between current and voltage in a purely resistive AC circuit?
There is no phase difference (θ = 0).
p.7
Three-Phase Phasor Systems
What is the normal sequence of rotation for a three-phase supply?
Red followed by Yellow followed by Blue (R, Y, B).
p.23
Phasor Diagrams Overview
What does line OA represent in the vector diagram?
The voltage across the resistive component, which is in-phase with the current.
p.12
AC Resistance and Impedance
What are the units for impedance in AC circuits?
Ohm's (Ω), the same as for DC.
p.26
Mathematical Representation of Phasors
What is the formula for calculating the rms value of the supply voltage?
V_rms = I * Z, where I is the current and Z is the impedance.
p.11
Phasor Diagrams Overview
What does the 'in-phase' effect represent in a phasor diagram?
It shows that voltage and current are aligned with no phase difference.
p.1
Phase Relationships in Sinusoidal Waveforms
What does a phase difference represent?
The angular difference between two sinusoidal waveforms of the same frequency.
p.19
Inductive Reactance and Phase Relationships
How does inductive reactance change with frequency?
Inductive reactance increases as frequency increases.
p.18
Inductive Reactance and Phase Relationships
What happens to the current when a 50Hz supply is connected to an inductor?
The current is delayed by 90 degrees and reaches a peak value before the voltage reverses polarity.
p.8
Phase Relationships in Sinusoidal Waveforms
How does the blue phase voltage relate to the yellow phase voltage?
The blue phase voltage lags V_YN by 120 degrees.
p.11
Mathematical Representation of Phasors
What does resistance represent in the complex domain?
A real number only, with no imaginary component ('j').
p.8
Phasor Representation and Rotating Vectors
What is the reference phase voltage in the given three-phase system?
The red phase voltage, V_RN.
p.20
Inductive Reactance and Phase Relationships
In a pure inductor, how does the current relate to the voltage?
The current lags the voltage by 90°.
p.7
Phasor Representation and Rotating Vectors
What does the symbol ω represent in the context of phasors?
The angular velocity in radians per second.
p.23
Phasor Diagrams Overview
What does line OD represent in the vector diagram?
The resulting supply voltage.
p.7
Three-Phase Phasor Systems
What type of connection can three-phase phasors represent?
Star or delta connected systems.
p.9
AC Resistance and Impedance
What is the impedance of a resistor connected to a time-varying supply?
It is simply its AC resistance, as the current is in-phase with the voltage.
p.4
Phase Relationships in Sinusoidal Waveforms
What happens to the designation of phasors when the current waveform crosses the horizontal zero axis?
The current phasor can be used as a new reference, making the voltage phasor 'leading' the current phasor by angle Φ.
p.10
Phase Relationships in Sinusoidal Waveforms
What happens when the switch is closed in an AC circuit with a resistor?
An AC voltage is applied, causing a current to flow that rises and falls sinusoidally.
p.10
AC Resistance and Impedance
What does Ohm's Law state in the context of an AC circuit?
The maximum voltage across the resistor is proportional to the current flowing through it.
p.8
Phase Relationships in Sinusoidal Waveforms
How does the yellow phase voltage relate to the red phase voltage?
The yellow phase voltage lags V_RN by 120 degrees.
p.23
Phasor Diagrams Overview
What does line OB represent in the vector diagram?
The horizontal current reference.
p.2
Phasor Diagrams Overview
What do phasor diagrams represent?
The phase of an alternating quantity at any instant in time.
p.8
Phase Relationships in Sinusoidal Waveforms
How does the blue phase voltage relate to the red phase voltage?
The blue phase voltage, V_BN, leads the red phase voltage, V_RN, by 120 degrees.
p.18
Inductive Reactance and Phase Relationships
What is the behavior of inductive reactance as frequency approaches zero?
Inductive reactance decreases to zero, acting like a short circuit.
p.1
Phasor Representation and Rotating Vectors
What is the point of origin in phasor diagrams?
The fixed zero point around which the vector pivots.
p.5
Phasor Addition and Subtraction
How can the phasor sum V1 + V2 be found graphically?
By drawing the two phasors to scale on graph paper and measuring the diagonal line known as the 'resultant r-vector'.
p.10
Mathematical Representation of Phasors
What is the expression for current in a purely resistive AC circuit?
I(t) = Im x sin(ωt + θ), where Im is the maximum amplitude and θ is the phase angle.
p.5
Mathematical Representation of Phasors
What is the Rectangular Form in phasor analysis?
A method that divides the phasor into a real part (x) and an imaginary part (y), represented as Z = x ± jy.
p.3
Phasor Diagrams Overview
How are the lengths of the phasors in the diagram determined?
They are proportional to the values of voltage (V) and current (I) at that instant in time.
p.1
Phase Relationships in Sinusoidal Waveforms
What terms are commonly used to describe the relationship between sinusoidal waveforms?
Lead, lag, in-phase, and out-of-phase.
p.19
Inductive Reactance and Phase Relationships
What is the relationship between inductive reactance (X_L) and frequency (ƒ)?
Inductive reactance is proportional to frequency (X_L α ƒ).
p.10
Phase Relationships in Sinusoidal Waveforms
What occurs to the current and voltage values in an AC resistance circuit?
They achieve their maximum, minimum, and zero values simultaneously.
p.12
AC Resistance and Impedance
What is the relationship between DC resistance and AC impedance for a resistor?
DC resistance = AC impedance, or R = Z.
p.26
Impedance in RL Circuits
How is the impedance of the circuit calculated?
Using the formula Z = √(R² + (XL)²), where XL = 2πfL.
p.13
AC Resistance and Impedance
What types of AC circuits typically consist of pure ohmic resistance?
Heating elements and lamps.
p.21
Phase Relationships in Sinusoidal Waveforms
What is the phase relationship between current and voltage in a purely inductive coil?
The current lags the voltage by 90°.
p.18
Inductive Reactance and Phase Relationships
How is inductive reactance related to frequency?
Inductive reactance is directly proportional to frequency.
p.21
AC Resistance and Impedance
What does 'purely inductive coil' imply?
It has no ohmic resistance and therefore no I²R losses.
p.22
Phasor Representation and Rotating Vectors
How is vector V_R represented in the vector diagram for a resistive circuit?
Superimposed to scale onto the current vector.
p.2
Mathematical Representation of Phasors
What forms can phasors represent mathematically?
Rectangular, Polar, or Exponential form.
p.27
Phasor Diagrams Overview
What does a phasor diagram represent?
The relationship between voltage and current in terms of their magnitudes and phase angles.
p.10
Phase Relationships in Sinusoidal Waveforms
What is meant by the term 'in-phase' in an AC circuit?
Current and voltage reach their maximum and minimum values simultaneously.
p.7
Phasor Addition and Subtraction
What geometric shape is used to represent phasor subtraction?
A parallelogram, where the vector difference is the other diagonal.
p.8
Three-Phase Phasor Systems
What points are the three windings of the coils connected to in a three-phase system?
Points a1, b1, and c1 for a common neutral connection.
p.5
Phasor Addition and Subtraction
How is the addition of two vectors A and B expressed in phasor analysis?
Using the generalised expression for phasor addition.
p.11
Phasor Diagrams Overview
How are the voltage and current vectors represented in a phasor diagram when in-phase?
They are drawn superimposed along the same reference axis.
p.22
Impedance in RL Circuits
What components make up the total voltage in an RL series circuit?
The component voltages V_R and V_L.
p.1
Phasor Representation and Rotating Vectors
What does the length of a rotating vector represent?
An AC quantity that has both magnitude (peak amplitude) and direction (phase).
p.20
Phasor Representation and Rotating Vectors
What is the significance of the phasor domain in AC circuits?
It allows for the representation of voltage and current as rotating vectors.
p.11
Applications of Phasor Diagrams in Circuit Analysis
What is the significance of the transformation from sinusoidal time-domain to phasor-domain?
It allows for easier analysis of AC circuits using RMS values.
p.21
AC Resistance and Impedance
Why is it impossible to have a purely inductive coil in the real world?
All coils have some resistance due to the resistivity of copper wire.
p.4
Phase Relationships in Sinusoidal Waveforms
What does it mean when the current phasor lags the voltage phasor?
It means the current phasor is behind the voltage phasor by the angle Φ.
p.3
Phase Relationships in Sinusoidal Waveforms
What must be considered when representing the relationship between two waveforms in phasor notation?
The phase difference, Φ, of the waveform.
p.20
Inductive Reactance and Phase Relationships
What does d/dt represent in the context of current?
The rate of change of current with respect to time.
p.18
Phase Relationships in Sinusoidal Waveforms
What is the phase relationship between voltage and current in a pure inductor?
Voltage leads current by 90 degrees, or current lags voltage by 90 degrees.
p.5
Mathematical Representation of Phasors
What does the Rectangular Form represent?
Both the magnitude and the phase of the sinusoidal voltage.
p.3
Phase Relationships in Sinusoidal Waveforms
What does a phase difference indicate in sinusoidal waveforms?
The angle by which one waveform lags or leads another.
p.7
Three-Phase Phasor Systems
In which direction do the phasors for a three-phase system rotate?
In an anti-clockwise direction.
p.14
AC Resistance and Impedance
How do you calculate the current drawn from the supply?
Using Ohm's Law: I = V/R.
p.16
Inductive Reactance and Phase Relationships
How does a coil behave at maximum current flow?
It acts more like a short circuit.
p.2
Phasor Representation and Rotating Vectors
What does the tip of the rotating vector represent at 0°, 180°, and 360°?
The angles at which the vector is horizontal.
p.15
AC Resistance and Impedance
How can Ohm's Law be applied in AC circuits?
It can be used to calculate voltages and currents in circuits containing AC resistance.
p.26
Phase Relationships in Sinusoidal Waveforms
What is the phase relationship of current lagging voltage in an inductive circuit?
Current lags voltage by 90 degrees.
p.10
AC Resistance and Impedance
How does the alternating current behave in a purely resistive circuit?
It varies in proportion to the applied voltage, following the same sinusoidal pattern.
p.20
Inductive Reactance and Phase Relationships
What does θ represent in the context of voltage and current waveforms in an inductor?
The phase difference or phase angle, which is +90°.
p.25
Mathematical Representation of Phasors
What is the supply voltage defined in the example?
V(t) = 325 sin(314t - 30°).
p.16
Inductive Reactance and Phase Relationships
How does current flow in an AC circuit compared to a DC circuit?
It behaves differently due to AC inductance.
p.16
Inductive Reactance and Phase Relationships
What factors determine the opposition to current in an AC circuit?
Inductance of the coil and frequency of the applied voltage waveform.
p.22
Phasor Representation and Rotating Vectors
How is vector V_L represented in the vector diagram for an inductive circuit?
Drawn 90 degrees in front of the current vector.
p.27
Phasor Diagrams Overview
What can be inferred from the phasor diagram?
The relative phase difference and amplitude of current and voltage.
p.3
Phasor Diagrams Overview
What does the phasor diagram represent at time zero?
The relationship between voltage and current.
p.12
AC Resistance and Impedance
What is the relationship between voltage and current phasors in a pure resistance within an AC circuit?
It is the same as in a DC circuit, showing a linear relationship.
p.7
Three-Phase Phasor Systems
What characterizes a balanced three-phase voltage supply?
Three individual sinusoidal voltages that are equal in magnitude and frequency, out-of-phase by 120 degrees.
p.20
Impedance in RL Circuits
What is the relationship between V_MAX and I_MAX in an AC inductance?
V_MAX = ωLI_MAX = √2V_RMS.
p.16
Inductive Reactance and Phase Relationships
What happens to the current in a coil after five time constants?
It reaches its maximum steady state condition.
p.2
Phasor Representation and Rotating Vectors
How is a complete sine wave constructed in phasor representation?
By a single vector rotating anti-clockwise at an angular velocity of ω = 2πƒ.
p.19
Inductive Reactance and Phase Relationships
What is the effect of self-induction in an inductor?
It produces an emf that counteracts the changing current.
p.17
Inductive Reactance and Phase Relationships
What type of circuit is described in the text?
A pure inductance circuit.
p.19
Inductive Reactance and Phase Relationships
What is self-inductance?
The effect where the magnetic field created by current opposes any change in current.
p.1
Phasor Addition and Subtraction
What is the main difference between vectors and phasors?
A vector's magnitude is the peak value of the sinusoid, while a phasor's complex magnitude is the rms value of the sinusoid.
p.1
Phasor Representation and Rotating Vectors
What remains the same for both vectors and phasors?
The phase angle, direction, and angular velocity.
p.4
Phasor Representation and Rotating Vectors
In which direction do the current and voltage phasors rotate?
They rotate in an anticlockwise direction.
p.14
Mathematical Representation of Phasors
What is the voltage supply in the sinusoidal voltage example?
V(t) = 100 x cos(ωt + 30°).
p.22
Phasor Representation and Rotating Vectors
What is the relationship between the scales of V_R and V_L in the vector diagram?
They are drawn to the same scale.
p.22
Mathematical Representation of Phasors
What is the purpose of finding a common component in vector diagrams?
To accurately represent the relationships between voltages and currents.
p.27
Phase Relationships in Sinusoidal Waveforms
How is the phase angle between current and supply voltage calculated?
Using the relationship between the phasors of current and voltage.
p.5
Phasor Addition and Subtraction
What is the downside of the graphical method for phasor addition?
It is time-consuming and may produce errors if not drawn accurately or to scale.
p.8
Phase Relationships in Sinusoidal Waveforms
What is the relationship between phase voltages in a three-phase system?
They are equal in magnitude but differ in phase angle.
p.18
Phase Relationships in Sinusoidal Waveforms
What mnemonic helps remember the phase relationship in a pure inductor circuit?
ELI, which stands for Electromotive force (E) leads Inductance (L) before Current (I).
p.13
AC Resistance and Impedance
How is instantaneous power consumed by a resistor calculated in a purely resistive circuit?
It is given by the product of voltage and current since they are in-phase.
p.3
Mathematical Representation of Phasors
What is the significance of the angle Φ in phasor diagrams?
It represents the phase difference between two sinusoidal quantities.
p.19
Inductive Reactance and Phase Relationships
What happens to the current flowing through an inductor as frequency increases?
The current flowing through the inductor reduces in value.
p.18
Inductive Reactance and Phase Relationships
What happens to inductive reactance when frequency increases?
Inductive reactance increases, approaching infinity as frequency approaches infinity.
p.2
Phasor Addition and Subtraction
What law do vectors in phasor diagrams obey?
The parallelogram law of addition and subtraction.
p.21
Impedance in RL Circuits
How is the total impedance of a coil represented?
As a resistance in series with an inductance.
p.15
AC Resistance and Impedance
What is the relationship between current and voltage in a pure ohmic AC resistance?
They are both 'in-phase' with no phase difference.
p.9
AC Resistance and Impedance
What is impedance in an AC circuit?
The effective resistance to current flow, measured in Ohms, including both AC resistance and AC reactance.
p.9
AC Resistance and Impedance
What can sinusoidal waveforms be transformed into for analysis?
The spatial or phasor-domain.
p.15
Inductive Reactance and Phase Relationships
What does inductive reactance depend on?
It depends linearly on the supply frequency.
p.2
Applications of Phasor Diagrams in Circuit Analysis
Why might we need to know the position of a phasor?
To compare two different waveforms on the same axis.
p.4
Phasor Addition and Subtraction
If V1 has a peak voltage of 20 volts and V2 has a peak voltage of 30 volts, with V1 leading V2 by 60 degrees, what is the first step to find the total voltage?
Draw a phasor diagram representing the two vectors.
p.23
Mathematical Representation of Phasors
What does I represent in the context of the circuit?
The r.m.s. value of the series current.
p.15
AC Resistance and Impedance
What does impedance (Z) consist of in a pure ohmic resistance?
A real part (the actual AC resistance value, R) and a zero imaginary part (j0).
p.9
AC Resistance and Impedance
How can voltage and current phasors be represented in an AC circuit?
Using complex numbers to represent a complex quantity.
p.17
Phase Relationships in Sinusoidal Waveforms
What can be said about the current when using voltage as a reference?
The current lags the voltage by 90 degrees.
p.23
Phasor Diagrams Overview
What geometric shape represents the resultant phasor diagram for the RL circuit?
A right-angled voltage triangle (OAD).
p.17
Phase Relationships in Sinusoidal Waveforms
What is the effect of the applied voltage reaching its maximum value in relation to the current?
The applied voltage reaches its maximum a quarter of a cycle earlier than the current.
p.24
Mathematical Representation of Phasors
What is the formula for impedance in terms of resistance and reactance?
(Impedance)² = (Resistance)² + (j Reactance)².
p.17
Inductive Reactance and Phase Relationships
How does the magnetic field affect the change in current?
It opposes or restricts the change in current.
p.24
AC Resistance and Impedance
What does impedance depend on?
The frequency (ω) of the circuit.
p.23
Inductive Reactance and Phase Relationships
What does V_L represent?
The I.X_L voltage drop across the inductance, which leads the current by 90 degrees.
p.2
Phase Relationships in Sinusoidal Waveforms
What does the time axis of the waveform represent?
The angle in degrees or radians through which the phasor has moved.
p.14
AC Resistance and Impedance
How do you find the peak value of the current flowing through the circuit?
Using Ohm's Law: I_peak = V_peak / R.
p.4
Phasor Addition and Subtraction
What method is used to determine the Resultant Phasor when adding out-of-phase voltages?
The parallelogram law is used.
p.22
Applications of Phasor Diagrams in Circuit Analysis
What is the significance of drawing vector diagrams in AC circuits?
To visualize the relationship between voltage and current.
p.17
Phase Relationships in Sinusoidal Waveforms
By how much is the current delayed in a purely inductive circuit?
90 degrees (or 1/4 of a cycle).
p.17
Phase Relationships in Sinusoidal Waveforms
What does the voltage do in relation to the current in a purely inductive circuit?
The voltage leads the current by 90 degrees.
p.16
Inductive Reactance and Phase Relationships
What does back emf do in a purely inductive coil?
It opposes the rise and fall of the current.
p.24
AC Resistance and Impedance
What does the RL Impedance Triangle represent?
The relationship between resistance, reactance, and impedance.
p.15
Inductive Reactance and Phase Relationships
How do inductors store energy?
In the form of a magnetic field created when a voltage is applied across the terminals.
p.21
Phasor Addition and Subtraction
What is the relationship between voltage and the component voltages in an AC circuit with resistance and inductance?
The voltage is the phasor sum of the component voltages, V_R and V_L.
p.4
Phasor Addition and Subtraction
What is a key use of phasors in circuit analysis?
They are used for summing sinusoids of the same frequency.
p.4
Phasor Addition and Subtraction
How do you add two in-phase alternating waveforms?
They can be added together like DC values to find the algebraic sum.
p.9
AC Resistance and Impedance
What relationship can be constructed using phasor diagrams?
The phasor voltage-current relationship.
p.23
Mathematical Representation of Phasors
How can the resultant voltage across the RL circuit be mathematically found?
Using Pythagoras' theorem.
p.2
Phase Relationships in Sinusoidal Waveforms
What phase angle is assumed in the waveform starting at time t = 0?
A corresponding phase angle in either degrees or radians.
p.25
Inductive Reactance and Phase Relationships
How is the inductive reactance of the coil calculated?
XL = ωL = 314 x 2.2 = 690 Ω.
p.21
Phase Relationships in Sinusoidal Waveforms
What happens to the phase difference when resistance is added to an inductive circuit?
The current still lags the voltage, but by an amount less than 90°.
p.24
Mathematical Representation of Phasors
How is impedance represented mathematically?
Z = R + jX_L, where R is resistance and X_L is reactance.
p.15
Inductive Reactance and Phase Relationships
What happens when an inductive coil is connected to an AC supply?
It produces a self-induced emf opposing the emf that initially set up the current.
p.14
Phase Relationships in Sinusoidal Waveforms
What is the relationship between voltage and current in a purely resistive circuit?
The voltage across the resistance is the same as the supply voltage.
p.23
Impedance in RL Circuits
What does V_R represent?
The I.R voltage drop across the resistance, which is in-phase with the current.
p.2
Phase Relationships in Sinusoidal Waveforms
What do the vertical positions of the vector represent?
The positive peak value at 90° and the negative peak value at 270°.
p.15
Inductive Reactance and Phase Relationships
What are inductors and chokes made of?
Coils or loops of wire wound around a hollow tube (air cored) or ferromagnetic material (iron cored).
p.23
Phase Relationships in Sinusoidal Waveforms
What is the relationship between current and voltage in a pure inductance?
The current lags the voltage by exactly 90 degrees.
p.2
Phasor Representation and Rotating Vectors
What does a phasor represent at a specific point in time?
A scaled voltage or current value of a rotating vector.
p.4
Phase Relationships in Sinusoidal Waveforms
What is the significance of the angle Φ in phasor relationships?
It indicates the phase difference between the current and voltage phasors.
p.16
Mathematical Representation of Phasors
What does the symbol 'ω' represent in relation to inductive reactance?
ω equals 2πƒ (angular frequency).
p.4
Phasor Addition and Subtraction
What must be considered when adding two out-of-phase voltages?
The phase angle between them must be taken into account.
p.9
AC Resistance and Impedance
What type of supply is considered when analyzing AC resistance?
A single-phase AC supply.
p.24
Phase Relationships in Sinusoidal Waveforms
What does the positive phase angle θ indicate?
The phase difference between voltage and current.
p.4
Phasor Addition and Subtraction
What is the result of adding two in-phase voltages of 50 volts and 25 volts?
The result is a total voltage of 75 volts (50 + 25).
p.24
Phasor Representation and Rotating Vectors
Is impedance a phasor?
No, it is the result of two or more phasors combined.
p.23
Phasor Addition and Subtraction
What is the formula for the applied voltage in the RL circuit?
The applied voltage is the vector sum of V_R and V_L.
p.15
Inductive Reactance and Phase Relationships
What determines the growth of current flowing through an inductor?
The inductor's own self-induced or back emf value.
p.15
Inductive Reactance and Phase Relationships
What is the relationship between back emf voltage (V_L) and current in an inductor?
V_L is proportional to the rate of change of the current flowing through it.
