What is Alternating current: Definition and 121 Discussions
Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen appliances, televisions, fans and electric lamps into a wall socket. A common source of DC power is a battery cell in a flashlight. The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage.The usual waveform of alternating current in most electric power circuits is a sine wave, whose positive half-period corresponds with positive direction of the current and vice versa. In certain applications, like guitar amplifiers, different waveforms are used, such as triangular waves or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. These types of alternating current carry information such as sound (audio) or images (video) sometimes carried by modulation of an AC carrier signal. These currents typically alternate at higher frequencies than those used in power transmission.
So we learnt about the different types of circuits and their behaviour when connected to an alternating current source.
(DC was treated as an AC with 0 frequency and/or infinte time period).
For purely inductive and purely capacitive circuits we were shown the derivation and why things are the...
Premise: the electric field inside a perfect conductor is zero.
The boundary conditions indicate that the tangential component is continuous, so the tangential component at the surface of the conductor is also zero. In conclusion, the electric field is perpendicular at the surface of a perfect...
Hi everyone,
I have a EE problem that I need to sort out for alternating voltage. I have to find out the maximum flux density.
B_max= integral from 150 degrees to 30 degrees (u/(2NA) dt is my problem.
I have a hard time to integrate this since I am to integrate with time and not degrees or...
Hi,I have found in my textbook the formulas for both current and voltage and I have no idea if they are right or wrong. Can someone help me with these formulas?
v=v0cos(wt)
i=i0cos(wt)
Is this correct? In google when I search for the answers I get something else:
v=v0sin(wt)
i=i0sin(wt)
Hi, I don't understand how to solve the problem below for (a).
First I transform the cirucuit to direct current problem using jw method. Now i see that U=-I2Z. Z=R2+Zc3=R2+1/jwC3=4,5+1/[j(1000)(10^-3*0,25)]. Then I use impedance transformation to get rid of the transformator(using Z0), but then...
I'm solving this exercise, first I did a force diagram for the transformer nucleus and I got this:
∑Fx = ma
P(t) - Fk - Fb = ma
P(t) = mx''+ bx' + kx
So I got that dynamic equation, my question is, after transform that dynamic equation to Laplace Domain how can I relate it with the Output...
For a current
i(t)=I_0\sin(\omega t+\varphi_0)
period is ##T=\frac{2\pi}{\omega}##,
Power is defined as
p(t)=Ri^2(t). So period of power is not any more ##T=\frac{2\pi}{\omega}##. Why then average power is
P=\frac{1}{T}\int^T_0p(t)d t.
Why are we using the period of current and not of the...
I had previously solved this using Root Mean Square method by integrating the value of voltage from t=0 to t=T/2 and then from t=T/2 to t=T.Answer was Vo/2½.Yesterday I found this question👇🏾
if I followed the previous approach then:
5 volts is not even in the option. How can I find the DC...
Preface to thread: The power source in both diagram 1 and diagram 2 is a wall outlet with alternating current power, not a battery. The load in both diagram 1 and diagram 2 is a light bulb, even though I forgot to label the load in diagram 2...
Hi all,
Kirchhoff's equation for this simple circuit is equivalent to
\dot I=\frac{V}{L}
Where V=V_0 \sin(\omega t). Integrating both sides should give
I(t) = -\frac{V_0}{L\omega} \cos(\omega t)+c
where c is an arbitrary constant (current).
Here, most of the derivations I've found simply drop...
So, as it says in the title, I am trying to calculate overall voltage induced in a coreless coil in the cases of it being stationary and moving in an alternating magnetic field. To go more into detail, I would like to create a mathematical model of a coil in an alternating magnetic field that...
I know the current of capacitor and inductor must be parallel but pointing in opposite direction due to the fact they are connected in parallel thus having same voltage (please see attached screenshots). The current of resistor will simply be the sum of these two vectors, but what about its...
I was reading The Feynman Lectures on physics http://www.feynmanlectures.caltech.edu/I_23.html chapter 23, section 4. In it he derives the equation for current when inductor, resistor and capacitor is connected in series with an alternating voltage source, he derives this equation:-...
Homework Statement
apparently your effective power is V_maxI_max * cos(x) where x is the phase angle. So I must consider only real power Homework Equations
power = VI
current = I sin(wt)
The Attempt at a Solution
Let impedence be = e^ix . I'll write current as Ie^i(wt) consideronly the real...
Since the classical Hall EMF is proportional to current, in an alternating current circuit, the Hall Emf should also follow an alternating pattern. Is it so? Or the Hall Emf doesn't change in a sine wave pattern instead remains more or less same and has a voltage based on the average/rms...
This question is from my physics book and neither I nor my teacher can find the mistake in my method. (The original question is not in English so I'll do my best translating it)
> When a coffee maker is connected to the wall (230 V, 50 Hz) its power consumption is 180 W. The power consumption...
I had learned from a book in a lower class that electric power distribution from the generating station is done in phases. Like in India, we have three phases of power transmission: the red, green and yellow colours distinguish the three phases. I believe the same is the case in any other...
In DC, we have learned that the electrons move from their position through the conductor, resulting in a current. They leave their positions on the application of a potential difference, and move or flow in the direction of higher to lower potential, thereby causing a current.
But what about...
Hello everybody
I got really confused. I want to calculate the Electric-Field of an alternating current source( Sine(wt)). I do not know what is its equation. I need to run it in Matlab to get a result. Can you please give me some hints?
I need to write the equation to calculate the E-field in...
Homework Statement
Three periodic currents have the same ##f=100 Hz##. The amplitude of the second current is ##4 A##. and is equal to half of the amplitude of the third current. Effective value of the third current is 5 times that of the first current. At time ##t_1=2ms## third current...
Homework Statement
From the given circuit and provided information draw a phasor and calculate the inductance.
Homework Equations
3. The Attempt at a Solution
[/B]
The paper was given to me at class as a solution to our homework and i can't understand how they drew the phasor and drew the...
Hello Experts,
I am a physics newbie with big ideas. I have a question.
I am thinking about how to produce a zero Resistance Current.
We know we can do this using super-conductors in sub zero temperature, but maybe there's another way.
My assumptions (which could be wrong):
1) Resistance in a...
Hi there,
I am a teacher and will be teaching the topic of alternating current soon. I have not taught this before and have certainly not studied this in many years so I am trying to get a full understanding and am looking for a bit of clarification.
So I know that the current supplied by the...
Homework Statement
So I'm trying to figure out this problem:
The base of our charging station is composed of a coil with N1 turns and area A1 connected to a 120 VAC, 60 Hz source. The device has a smaller coil with N2 turns and area A2, which when attached will fit completely inside the...
Homework Statement
https://goo.gl/wifHB3
{Image from: Electricity - Basic Navy Training Courses; NAVPERS 10622}
http://imgur.com/a/Pm2Rl
Here are two images, the one with colours is from my textbook. I don't understand why u is 0 when the thing inside is parallel with the ground and why...
As the title implies, I'm looking for a textbook on alternating current (not necessarily containing only about this topic). I'm looking for such a book with the following things in mind:
- Is not just some introductory thing, but a book that treats the subject in an advanced manner using at...
Some say that AC should form a closed loop circuit for electricity utilization but is there really an loop from the Power station(hot wire) to the Ground(neutral) and then from Ground to power station so that it forms a loop?
To my understanding, capacitors cause the current to lead the voltage which adds VARS to the circuit and inductors cause the current to lag behind the voltage which removes VARS (in AC circuits). Also, it is my understanding that VARS increase voltage. I work for one of the largest utilities...
Hey everyone, I've been kicking around this idea for fusion for a while and thought everyone could check my understanding. The idea is to create a sustained z pinch using alternating current sources in parallel...
Homework Statement
If the peak values of current through inductor (L), capacitor (C) and resistor (R) in parallel AC circuit are 2mA, 3mA, and 5mA respectively, then the peak value of current delivered by the source in the same circuit will be
Homework EquationsThe Attempt at a Solution
i (R)...
Hi Everyone,
I have 4 scenarios in question . Will The EMF(Voltage) be the same in all of the scenarios?
- the difference between the two photos are the polls: one repel one attract .
- i understand that the current(amps) will change due to the wire length assuming same gauge
1) Photo...
Homework Statement
I've been struggling to fully understand the difference between Varying Direct Current and Alternating Current. Please explain this to me. Also, how would they differ on a Current-Time graph?
Homework Equations
E = int (VI dt)
The Attempt at a Solution
Homework Statement
A series L-C-R circuit Comprises of a 250mH coil, 0.01 MFD capacitor and a 5W resistor. A dependent voltage defined by e = 2.5cos(80000t) is applied across it. Determine the power factor. [/B]
Homework Equations
Power Factor = cos(x) = R/Z
Z = sqrt^[R^2 + (XL - XC)^2]
The...
Homework Statement
An inductor has a resistance of 30 Ohm and an inductance of 0,1 H. A current with the peak value of 2 A runs through. Calculate the effect factor and the active effect if it connects to a grid with 230V and a frequency of 50 Hz.
My book says that the effect factor is 0,69...
Hi, I have a few questions regarding magnetic levitation achieved by using alternating current to induce eddy current on a non-ferromagnetic conductor plate to provide the levitation force.
1. Can it be stabilized? If yes, in what ways?
2. Are there any equations/formulae or ways to calculate...
When my classmate report about cycloconverters. He discussed about different classifications and types of cycloconverters. He also discussed how Single-phase to Single-Phase Cycloconverters operate. But when he approached Three-Phase to Single-Phase and Three-Phase to Three-Phase...
I understand the process of rectification but just only in theory. But I still have questions that I guess will be answered if I can experience or has experience about it (but sadly I don't have). Please kindly answer these questions:
1. Does the waveform of Vout can be considered as DC (...
I'm delving into AC as well as attempting to understand the various wave forms used in electrical engineering, and I am curious how engineers are able to generate current which alternates in a sinusoidal manner. What specific phenomena allows us to achieve this? Is it a special circuit, or does...
Homework Statement
I'm supposed to find the current in a circuit with a voltage source, capacitor, and resistor in series. The voltage source is described by V=V0ejwt.
Here, j is the complex number j2=-1, and i is the current
Homework Equations
I=C*dv/dt
The Attempt at a Solution
I have...
I'm a bit confused on some of the fundamentals of Alternating Current, if anyone could help me out it would be awesome.
1) In what form is the mechanical energy provided to an alternator to produce the electrical energy? Does someone sit at each generator and spin a hand-crank (joke)?
2)...
When households are said to be grounded using an Earth wire, electrons are supposed to flow to the ground because the ground is at zero volts. For example, if your the live wire touches the metal casing of your toaster then the Earth wire takes the current to ground. But isn't a lot of household...
Homework Statement
Consider v1 = 30 sin(ωt + 10º) and v2 = 20 cos(ωt - 40º)
A: v1 is in advance to v2
B: v1 differs 50º from v2
C: v2 is in advance to v1
D: v1 is in quadrature to v2
Homework Equations
The Attempt at a Solution
I think the correct answer is A because v1's angle is nearer...
Homework Statement
Explain the use of a single diode for the half-wave rectification of an alternating current.
The Attempt at a Solution
A rectifier is a device that converts an alternating current, which periodically changes polarity, to direct current, which flows in only one...
All I have read in the electricity class is that AC is any type of current which actually reverses its directions periodically. I have also read all sorts of mathematical expressions concerning sine-wave form of AC. I have also understood how AC generator works. These topics had never bothered...