PowerPoint Presentation

[Audio] Welcome, everyone! We are here today for an introduction to Alternating Current, or AC—a type of electric current that changes directions. I am excited to introduce you to this concept, and explain the differences between AC and Direct Current (DC), and the role that it plays in powering our world. Let's get started!.

[Audio] AC is a type of electrical current which is used to deliver energy from power sources to outlets and devices. It is the most widely used form of electricity today, and is present in most homes, businesses, and other facilities. AC is a type of current which reverses its direction periodically, producing a sine wave, and is responsible for carrying energy between poles. This is in contrast to direct current (DC) which only moves in one direction. AC is generated by electrical power plants and then distributed across the grid through transmission lines..

[Audio] AC stands for Alternating Current, an electrical current that reverses direction periodically in order to provide a continuous flow of electricity. This differs from Direct Current (DC) which flows in one direction only. The voltage source of the current that creates alternating current is continuously alternating from positive to negative. This causes the current to move in one direction and then the opposite. This cycle is typically represented by a sine wave with peak values of voltage or current. The positive and negative halves of the wave need to be equal in magnitude in order for the alternating current to continue..

[Audio] Direct current is the other type of current used in electrical systems, characterized by a current flow in only one direction that can be represented by a straight line on a voltage versus time graph. Unlike Alternating Current which changes direction periodically, direct current maintains a consistent voltage and remains constant over time, making it an ideal power source for many electronic devices..

[Audio] Electric charge can flow in different directions depending on the type of current. Alternating current (AC) is characterized by a periodically changing flow of charge, while direct current (DC) is characterized by an uninterrupted flow of charge in one direction. This distinction between AC and DC systems explains why they are employed in different ways - AC is used for generating and transmitting electricity, while DC is used for powering machinery and electronic devices. Each system has its advantages and disadvantages, so it is important to determine which system is best for a particular application..

[Audio] Voltage in alternating current (AC) is calculated using the equation V = Sin (2πft), where V stands for voltage, f for frequency, and t for time. The variable θ (phase angle) represents the amount of time between the start of a waveform and a given point on the waveform, which is equal to ωt, where ω is the angular frequency (2πn, where n is the number of cycles per second). This equation shows that voltage in an AC system is determined by the frequency of the waveform, the phase angle, and the time. With a higher waveform frequency, there is a greater voltage in the AC system, making it useful for many applications such as providing electric power and running motors. Understanding this equation can help make better use of alternating current by understanding the relationship between voltage, frequency, and time..

[Audio] AC and DC are two types of electric current that have different uses. AC involves voltage and current that change directions periodically, creating a sine wave with peak voltage values. DC, on the other hand, flows in a single, constant direction. Representations of AC and DC sources show their varying voltage waveforms. This is the main difference between AC and DC, and it explains how the currents are used for different purposes..

[Audio] Electric current can take many forms and alternating current (AC) is one of them. This type of current involves a sine-shaped wave that changes its direction continuously. This is often compared to direct current, which moves only in one direction. Producing AC power requires an AC generator, transformer and motor. AC generators rely on electromagnets to create the sine wave, while transformers and motors make it possible to convert electricity from one form to another. We can find AC power being used for different purposes such as lighting, heating and cooling both in residential and industrial buildings worldwide..

[Audio] An alternating emf is an electric charge that reverses its direction and fluctuates in magnitude over time. It is conventionally shown as a sine wave with a peak voltage or current. It is typically abbreviated as AC or ac and not A C or a.c. The instantaneous emf is denoted by 'e' and its maximum value is indicated by 'e0'. The relationship between the two is expressed in the equation e = e0 sin wt, wherein w stands for the angular frequency..

[Audio] The graph between the instantaneous value of AC and time produces a sine curve with the positive half cycle, or positive pulse, being the variation of current or voltage from 0 to π above the reference line and the negative half cycle, or negative pulse, being the variation from π to 2π below the reference line. The part OAB is the positive half cycle and BCD is the negative half cycle while the reference line sets the point of comparison for the current or voltage values..

[Audio] AC power is transmitted to remote locations at high voltage and low current compared to DC power in order to reduce power loss over longer distances. This also lowers potential safety risks as the current is lower. Additionally, AC power is more efficient as transformers can be used to shift lower voltage to a higher voltage, thus minimizing power loss during the transmission process..

[Audio] Correct abbreviation for alternating current is A C , short for alternating current. This kind of current cycles direction regularly and is symbolized by a sine wave with maximum voltage or current values. It contrasts with direct current (DC), which moves in one direction..

[Audio] The Instantaneous Value (I) of the Electromotive Force (EMF) is the amount of voltage at a certain point in an alternating current. It is determined by the peak voltage of the sine wave, and it is important to measure in order to calculate the power consumption of a device..

[Audio] The instantaneous value of current or voltage in an AC circuit is determined by the peak or maximum value, also referred to as the crest value or amplitude. This peak or maximum value of the current is called the instantaneous current (I0), and the peak or maximum value of the voltage is referred to as the instantaneous emf (ε0)..

[Audio] The mean or average value (I avg or ε avg) of a sine wave is determined by taking an arithmetic average of all the instantaneous values of the wave in a single half-cycle. This is preferred to using a full cycle, since the average current within a full cycle is zero because the alternating current or voltage in the first half cycle is positive, whereas the other half cycle is negative..

[Audio] The mean value of a function f(t) from t1 to t2 is a way to measure the average value of the function over that interval. It is calculated by integrating the function between t1 and t2 and dividing by the size of the interval. This average value gives an idea of the overall behaviour of the function on that interval..

[Audio] The Root Mean Square (RMS) of a half-cycle of alternating current is an important value to consider. It is found by taking the square root of the mean of the squares of the individual data points, and is used to accurately measure the power being consumed without the need for an analog meter. Knowing this value is essential for the safe and efficient use of AC electricity..

[Audio] The root mean square value, or RMS, is an important concept when dealing with alternating current. It describes the average of the instantaneous voltages or current values of a voltage or current waveform across a periodic cycle. To calculate this value, the square root of the average of the squares of all the instantaneous values of a current or voltage waveform over a cycle must be taken. It is also referred to as ‘effective value’ or ‘virtual value’. This concept can similarly be applied to the emf waveform, where the square root of the mean of squares of all the instantaneous values of emf over one complete cycle is called the “root mean square emf”. Knowing the RMS value is crucial for understanding the magnitude of an alternating current..

[Audio] RMS value of current is a measure of the magnitude of an alternating current which can be calculated by using the formula I = I0 sin wt. The formula supplies the average of the current over one cycle, where I is the peak value, w is the angular velocity and t is the time..

[Audio] The root mean square (rms) value of alternating current is a measure of its magnitude or intensity. AC source voltage is the rms voltage, and the current in an AC circuit is the rms current. Moreover, AC ammeters and voltmeters measure the rms, also known as the effective, value of alternating current and voltage respectively..

[Audio] Alternating current, or AC, can be measured using instruments known as "hot wire ammeters" and "hot wire voltmeters". This is due to the fact that the heat produced is not dependent on the direction of the current. The heating effects of AC power is the same as that of DC power of equivalent magnitude, which is calculated in terms of root-mean-square current or I-rms..

[Audio] When it comes to alternating current, certain considerations should not be overlooked. AC carries a greater risk than the same voltage of DC, for instance, 200V DC would be equivalent to E0 = 200V. AC is generated using the principle of electromagnetic induction. Furthermore, ohm's law and joule's heating law are applicable to AC..

1. If I 0 is peak current then rms current ( I rms ) is……..

[Audio] Discussing alternating current (AC), peak voltage is a key factor. Peak voltage is the maximum voltage attained at the peak of a sine wave. Calculating the average emf during the positive half cycle of an AC supply of peak value ?₀ involves a few different calculations, the equation for which is ?₀ divided by either π or 2π. It is clear that peak voltage of an AC supply is important and the average Emf of the positive half cycle of an AC supply is determined by the equation ?₀ divided by either π or 2π..

[Audio] AC current displays various behaviors when it passes through pure resistors, inductors, and capacitors. A pure resistor maintains the current invariable regardless of frequency, while a pure inductor offers reactance that rises with an increase in frequency. Differently, a pure capacitor offers reactance that decreases with an increase in frequency. The current passing through a combination of resistors, inductors, and capacitors is defined by the characteristics of each element. Comprehending the behavior of AC current through these components is critical for electrical engineering applications..

PHASE OF AC. The term ‘ ?t’ is phase of alternating current ( emf ) and is defined as the fraction of time period that has elapsed since the current ( emf ) last passed its zero value in positive direction..

[Audio] Phasor is a quantity that has magnitude and direction in the time domain, typically expressed as a vector that changes over time. To analyze alternating current (AC) and electromotive force (EMF) circuits, it is useful to represent them graphically on a phasor diagram. AC and EMF vary sinusoidally with time, usually at the same frequency, which usually results in them being out of phase with each other. Depending on the circuit, current may lead or lag the EMF. A phasor diagram helps to make the study of such AC and EMF circuits easier..

[Audio] The Phasor or Argand diagram is a graphical representation of alternating currents and electromotive forces as vectors. Electric power and current can be expressed as a sinusoidal wave function of time, which is represented by two equations, with the angular velocity, ?, equal to 2?ft and the voltage, E, represented by the equation: E= t Sin t. This diagram helps to comprehend the properties associated with AC circuits..

[Audio] An alternating current moving through a pure resistor will have current that is proportional to the applied emf, with the current taking the form of I = ε₀ sin ωt, with ε₀ being the peak emf and ω being the angular frequency..

[Audio] AC sources have an instantaneous potential difference and current that vary depending on time. Equation one states that the voltage across the output of an AC source is V-max sine of omega t, while equation two illustrates that the current follows I equals I-max sine of omega t. This is due to Ohm's Law which states that the current in a circuit is proportional to the voltage. With this understanding of the relationship between voltage and current, it is possible to identify the behavior of AC sources..

[Audio] Phasor diagram is a graphical representation of a sinusoidal waveform which displays both the amplitude and the phase of the waveform. It provides a visual representation of AC electricity behavior since in AC the voltage and current are always in phase, reaching maximum value and minimum value at the same time. Equations one and two further demonstrate that the phase difference between voltage and current is equal to zero..

[Audio] An inductor in a pure inductive circuit has a unique alternating current. When an alternating voltage of ? 0 sin t or V 0 sin t is applied, the circuit has a phase difference of 90° in which the current lags the applied voltage. This leads to the equation ?=? 0 sin t or V=V 0 sin t giving the impedance offered by the inductor as purely resistive. The alternating current is the result of the inductive reactance, which is calculated from the formula for the applied voltage divided by the current..

(2). ? = ? 0 sin t. Hence, the phase difference between the emf and current is /2 radian or 90 0..

[Audio] The EMF and current vectors have a 90-degree phase difference between them, which is equal to a quarter cycle or π/2 radians. This phase shift is graphically presented in a phasor diagram, showing the offset between the two vectors of EMF and current..

[Audio] Inductive reactance is an important characteristic of an AC system. It is the opposition to current flow experienced by an inductor. Its units and dimensions are equal to that of resistance and is expressed as ohms (Ω), with its dimensional formula being [ML2T-3A-2]. This opposition can be calculated using the equation X L=ωL, where ω is equal to 2π times the frequency of the AC sinusoidal waveform. The rms emf is equal to the rms current through the inductor multiplied by the inductive reactance..

[Audio] A capacitor in an AC circuit is a vital element as it is able to retain energy in the form of an electric field. An alternating current connected to the capacitor leads to a sinusoidal voltage following the equation E=E0sinωt. This sinusoidal voltage is what enables the capacitor to store energy, with V=V0sinωt. As the current passes through the capacitor, the charge on the capacitor q changes with the equation q=CV. The rate of change of charge is measured by the differential equation, dq/dt=I. This allows the capacitor to store current, exchange energy, and act as a high-frequency path for the alternating current..

[Audio] The given equation is an expression for the instantaneous current through the capacitor. The current is in phase opposition to the applied emf, meaning there is a constant phase difference of -90 or -π/2 radians between them. This phase difference is denoted as φ and can be expressed as ωt - (ωt + π/2). This formula offers a way to calculate the current value of a capacitor at any point in time..

[Audio] Capacitive reactance plays an important role in Alternating Current (AC) circuits. It is the opposition presented by a capacitor when current runs through it. Sharing the same unit of measurement and dimensions (ML2T-3A-2) as resistance, it is denoted as Xc and is calculated using the equation ?rms = Irms Xc, where 'Irms' is the Root Mean Square (RMS) current through the capacitor. Being able to measure capacitive reactance is vital for apprehending the operation of AC circuits..

[Audio] Phasor and vector diagrams for pure resistor, pure inductor, and pure capacitor load types circuits can be seen illustrated in this slide. The phasor diagrams show the voltage and current waveforms of the circuits, with the fundamental component of each represented as resistance, capacitance, and inductance respectively. Gaining knowledge in these diagrams can help in gaining an understanding of the behavior of AC circuits..

[Audio] The current in an AC circuit containing only capacitance is said to lead the voltage by 90 degrees, meaning the current reaches its peak amplitude before the voltage reaches its peak amplitude. This phase shift between the current and voltage should be taken into consideration when designing or calculating the behavior of AC circuits..

[Audio] An alternating current source connected across a resistor will result in a current that is either leading, lagging behind, or in phase with the voltage. The current will lead the voltage if its phase is ahead of the voltage, lag behind the voltage if its phase is behind the voltage, and be in phase with the voltage if its phase is the same as the voltage..

Thank you….