Understanding Amplitude in Electrical Engineering

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Questions and Answers

What is another name for the highest positive or negative value obtained by an alternating quantity in a single full cycle?

Instantaneous Value

Frequency

Peak-to-Peak Value

Amplitude (correct)

What does 'f=1/T' represent in the context of alternating quantities?

Time Period

Peak Value

Frequency (correct)

Waveform

How is the time taken in seconds by a voltage or current to complete one cycle denoted?

T (correct)

What is the shape created by charting the instantaneous values of an alternating variable like voltage and current along the y-axis and time (t) or angle along the x-axis?

Waveform Signup and view all the answers

Which value represents the difference between the peak positive value and the peak negative value of a sine wave?

Peak-to-Peak Value Signup and view all the answers

What does 'Vm' represent when discussing alternating quantities?

Maximum Voltage Value Signup and view all the answers

What does 'Im' represent when discussing alternating quantities?

Maximum Current Value Signup and view all the answers

Which term is used to describe the value of voltage or current at any given time?

Instantaneous Value Signup and view all the answers

What unit is frequency measured in?

Hertz (Hz) Signup and view all the answers

During each complete cycle of an AC signal, how many peak values are there?

Two Signup and view all the answers

What is the average value of alternating current over a complete cycle for sinusoidal waves?

Zero Signup and view all the answers

What is the formula for the average current for one alteration in a sinusoidal waveform?

$0.636 Imax$ Signup and view all the answers

What is the RMS value of an AC wave defined as?

Square root of means of squares of instantaneous values Signup and view all the answers

In a purely resistive AC circuit, what is dissipated by the resistors?

Power Signup and view all the answers

What does a purely inductive circuit contain?

Only inductance Signup and view all the answers

What is the phase angle between voltage and current in a pure resistive AC circuit?

$0$ degrees Signup and view all the answers

In a purely inductive circuit, by how many degrees does the current lag behind the voltage?

$90$ degrees Signup and view all the answers

What opposes the flow of current in a circuit with inductance?

Inductive reactance Signup and view all the answers

What is the average value formula of alternating quantities for sinusoidal waves?

$0.636 Vmax$ Signup and view all the answers

What does RMS stand for concerning AC power?

Root Mean Square Signup and view all the answers

What is the phase angle when XL > XC in an RLC Series Circuit?

Positive Signup and view all the answers

In what scenario does the RLC Series Circuit behave like a purely resistive circuit?

XL = XC Signup and view all the answers

What is the total opposition offered to the flow of current by an RLC Circuit known as?

Impedance Signup and view all the answers

What is the power factor when XL < XC in an RLC Series Circuit?

Leading Signup and view all the answers

What is the formula for calculating total impedance (Z) in an RLC Series Circuit?

$\sqrt{R^2 + (XL - XC)^2}$ Signup and view all the answers

What is the relationship between voltage across the resistor and current in an RLC Series Circuit?

Directly proportional Signup and view all the answers

When XL = XC, how does the voltage across each element in an RLC Series Circuit behave?

Voltage and current are in phase Signup and view all the answers

What happens to the circuit behavior when XL < XC in an RLC Series Circuit?

Acts as a capacitive circuit Signup and view all the answers

What is the key difference between voltage across the inductor and voltage across the capacitor in an RLC Series Circuit?

Voltage across the capacitor leads by 90 degrees Signup and view all the answers

What does a positive phase angle signify when analyzing an RLC Series Circuit?

Circuit behaves like an RL series circuit Signup and view all the answers

What is the relationship between current and voltage in a pure inductive AC circuit?

Current lags the voltage by 90 degrees Signup and view all the answers

In a circuit with a pure capacitor only, what is responsible for storing electric power?

Capacitance Signup and view all the answers

What happens to a capacitor when the supply is turned off?

It discharges Signup and view all the answers

In an RL Series Circuit, what is the total opposition offered to the flow of alternating current called?

Impedance Signup and view all the answers

What is the impedance of an RL Series Circuit composed of pure resistance and pure inductance?

$\sqrt{R^2 + X_L^2}$ Signup and view all the answers

Study Notes

Alternating Current (AC) Basics

Amplitude: The highest positive or negative value of an alternating quantity in a single full cycle, denoted by Em or Vm for voltage and Im for current.
One Full Cycle: A collection of positive and negative values that completes a full rotation of 360 degrees electrically.
Instantaneous Value: The value of voltage or current at any given time, denoted by i or e.
Frequency: The number of cycles per second, measured in hertz (Hz) or cycles per second (c/s).
Time Period: The time taken in seconds to complete one cycle, denoted by T.
Waveform: A shape created by charting instantaneous values of an alternating variable along the y-axis and time (t) or angle (θ) along the x-axis.

Peak and Peak-to-Peak Values

Peak Value: The maximum value obtained in either the positive or negative direction, measured from zero.
Peak-to-Peak Value: The difference between the peak positive value and the peak negative value, which is twice the maximum or peak value.

Average Value of AC

Average Value: The average of instantaneous values over a complete cycle, which is zero for asymmetrical waves.
Formulae: Vavg = 0.636 Vmax for voltage, and Iavg = 0.636 Imax for current.

RMS Value of AC Wave

RMS Value: The square root of the mean of squares of instantaneous values, equivalent to the DC power that generates the same heating effect.
Definition: The amount of AC power that generates the same heating effect as an equivalent DC power.

Purely Resistive Circuit

Circuit Characteristics: Contains only pure resistance R ohms, with no effect of inductance and capacitance.
Voltage and Current: Move in both directions, producing a sine wave.
Power Dissipation: By resistors, with no phase difference between voltage and current.

Purely Inductive Circuit

Circuit Characteristics: Contains only inductance, with no effect of resistance and capacitance.
Current: Lags behind the voltage by 90 degrees.
Inductive Reactance: The opposition to the flow of current, caused by the time-varying magnetic field.

RLC Series Circuit

Circuit Characteristics: Contains a combination of resistance, inductance, and capacitance.
Impedance: The total opposition to the flow of current, denoted by Z.
Phase Angle: The angle between the applied voltage and current, dependent on the relative values of XL and XC.

Phasor Diagram

Phasor Diagram: A graphical representation of the voltage and current in an RLC circuit.
Circuit Behaviour: Can be inductive, capacitive, or purely resistive, depending on the relative values of XL and XC.

Problem Solving

Example Problem: A series circuit with R = 200, L = 0.08H, C = 100µF, and a 250V, 50Hz supply.
Solutions: Calculating reactance, current, impedance, power factor, power consumed, and voltage across each element.

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Description

Learn about the concept of amplitude in electrical engineering, which refers to the peak or maximum value of an alternating quantity in a single full cycle. Explore terms like maximum voltage, maximum current, one full cycle, instantaneous value, and frequency.