Alternating current Definition and 121 Threads

Hello physicsforums. I'd like to apologize for submitting such a fool thread. Anyway, I'm in disagreemeent with my friend who thinks it was Nikola Tesla who invented AC, but I insist that it was not him. I tried to google it, but I have yet to find a proper answer. He's like, " My physics...

Homework Statement part 1. at what frequencies will the circuit act as a differentiator? part 2. interchanging R and C of figure D produces a low pass filter. At what frequencies will v_out/v_in = .95? part 3. at what frequencies will the RC circuit of problem 18 act as an integrator? part...

Hello, I was being taught AC in High School, It was good but the way they taught us DC, things like drift velocity, no of electrons per unit volume etc, it was easy to visualize electrons rushing in a conductor. I tried to visualise AC(which was not taught to us) and I came to a conclusion...

I'm having a difficult time understanding precisely how alternating current works in relationship to ground (earth). I have spent hours trying to learn online and I get conflicting explanations. So let's start with a power plant. A coil of wire is rotated in between magnets, inducing a...

So I get the general idea of electricity being the flow of charge (or lack of electrons) but when it's alternating I don't quite understand what's going on. So the current is just pulsating back and forth? How do they refer to this bring the transmission of electrical energy?? Isn't it...

I'm just learning the basics of electromagnetics and am a bit confused as to how ac works. From my understanding, a rotating conductive wire in a magnetic field create a current that changes direction from positive to negative flow, modeled in accordance with the sine function. But i was...

Homework Statement Two serially connected impedances one with \Phi = π/3 and other with \Phi = 0. They have apparent power of S1=S2=200VA. Find total apparent power. Homework Equations S = sqrt(P^2 + Q^2) The Attempt at a Solution so cosPhi = P1/S1. So P1=cosπ/3*200=100W...

Homework Statement Complex current of I = (1+j) on frequency of 50 Hz. Find maximum current Im, effective current Ief, and current at time 1s, i(1) Homework Equations ω=2πf i(t)=Im*sin(ωt+ψ)A The Attempt at a Solution Effective current is length of that hypotenuse on complex...

We know that a direct current generates a magnetic field which surrounds the wire in circular patterns (right-hand rule). However when alternating current runs through a wire, no actual electrons are transported from one end to the other but rather they "vibrate" so to speak and transmit this...

Homework Statement An alternating current generator consisting of a rectangular loop of length a = 0.1xm and width b = 0.1ym with N= 1w0 turns is rotated at a frequency f = 1.z Hz in a uniform magnetic field B= 0.1 T which points into the page. A load resistance R = 10 Ω completes the...

The magnitude of current of alternating current varies with time The power developed by the electrical appliances, let's say an electric fan, also varies with time But why the fan can still operate uniformly? Or the AC is changed to DC in the electric fan?

I understand direct current perfectly fine as it is just the continuous flow of electrons, but what is alternating current. I have heard it explained as the continuous switching of a currents direction 50 or 60 times a second, but that is so vague and confusing. Do the electrons move back and...

As the title suggests, how are very high frequency AC produced? A AC generator must have a limit to the rotation velocity of the coil, mustn't it? Any help would be appreciated. Thanks.

How alternating current was transmitted over a long distance? If it is direct current then I can imagine the constant current will flow over that long distance but how ac? Compare with ac, why dc decreases as it is transferred over long distances? Thank you.

The specific problem I'd like to know is let's say you have Mr electron (E) in a the wire, denoted by "---" Lets assume 0.5hz AC for now. Below is a snapshot in time of the electron in the wire. 1s ------E------- 2s -----------E-- 3s-------E------- 4s------------E-- 5s-------E------- Lets...

I have this Question about toaster and electric kettle and I just want to know if they are working on alternating current or direct current. Does a Toaster works on alternating current or direct current? and why? Does a electric kettle runs on alternating current or direct current? and...

Homework Statement The goal of this problem is to find a frequency at which the voltage drop across several components of a circuit will be zero. The circuit is identical to a wheatstone bridge (where two pairs of two resistors in series are wired in parallel) except that opposite...

I'm trying to understand the qualitative relationship of voltage and the a.c. through a pure inductor. My books says that to maintain the current in the inductor, the voltage across the inductor provided by the a.c. supply must be equal to the back emf but in the opposite direction. I'm quite...

An AC generator with an rms voltage of 25 V is connected in series with a 10 ohms resistor a 53 mH inductor, and a 65 micro F capacitor. Find a) the resonance frequency of the circuit, b) the impedance at resonance, c) the rms current at the resonance.

Hi All, I have a very basic question in understanding alternating current. When we learn about DC circuits we would start with a simple circuit with a resistor with one current direction (either electron or hole current) and it was said that electors move in one direction. But when we...

I have a problem conceptualizing the law of motion for the electromagnetic field in the case of the alternating current. Describing this conundrum takes too much time and a mix of too many ideas, so I thought about a problem that would encompass all that in a short and simple manner. I think...

Alternating Current: Cant understand the question!... Hi guys... I was trying this question out (from alternating current) but I'm not sure whether i should do what the solution book says or listen to what my course teacher said (This is not homework, I am just not clear about a line in this...

I've only taken one introductory class to DC circuits where we learned Ohms law and series parallel combined circuits. Now I'm in an introductory class to AC circuits and last night's entire lecture (first day of the semester) was just over my head. We didn't go over any fundamental concepts...

My professor crammed an alternating current (AC) into one lesson. I have an OK understanding of AC but my question is as follows. Let's assume that our voltage goes from 60V to -60V, at some point the potential difference is 0 and I would think the current itself would also be 0. Does that mean...

Homework Statement An alternating voltage is given by v = 30\sin(314t).The time taken by the voltage to reach 30V for the first time is: A. 0.02s B. 0.03s C. 0.1s D. 0.015s Homework Equations google for equation for instantaneaous current and voltage The Attempt at a Solution 30 = 30sin(314t)...

I was at a symposium the other day where the speaker was discussing the ability to create an AC current using a piezoelectric material, and this can be used to create or replace batteries. One of the professors stopped him and mentioned that this is not possible unless the voltage is at few...

what is the difference between an analog signal and alternating current??

If the frequency of a source is doubled in a R-L-C series circuit,what will happen to the resistance ,the inductive reactance and the capacitive.Homework Equations f=1/2pi√LC XL=2.pi.f.L XC=1/2.pi.f.C R=Vrms/Irms i coludn't know which formula to use am confused please help ...

Hello.This is my new task. Homework Statement Find e(t),i(t),Ul(t),Ur(t),Uc(t),Urc(t),Url(t). Find reactive power and complex power. Homework Equations What to do with Ulc(t)?The Attempt at a Solution C=200microfarad L=3millihenry r=4 Ohms Ulc(t)=17.89sin(1000t-64) I've done this Zc=-j/wC...

Homework Statement A 25 W (P), 100 V heater (V(h)) is to be run from a (V) 250 V 50 Hz (f) sinusoidal AC supply. Calculate the inductance (L) of a suitable choke to be included in the circuit. Assume its resistance to be negligible. Homework Equations P = V(h)*I*cos(alfa) I = V/Z...

the book says: Effect of alternating current (a.c.) on a capacitor The size of the current will depend on the capacitance and on the frequency of the supply. If the capacitance is small, or the frequency low, only a small amount of charge needs to flow onto the capacitor plates for the p.d...

Hi, PF :) I was self-studying AC circuits, and my main goal right now is to understand impedance. However, before that, I was wondering how one would derive the formulas for alternating voltage (and current), namely http://upload.wikimedia.org/math/5/a/0/5a0ecaa1432c6cdce653a943b4962a21.png...

Hi everyone, I've been studying magnetic fields and alternating current generators and i have a question i need help answering. I have posted a few other questions in which i posted my generator design with magnet placement and plotted the sine waves on a chart but i have a question about the...

Homework Statement A problem from a translated Sears-Zemansky, 1965, 14-10: A conduction coil with inductance of 15 miliHenrys and resistance of 10 Ohms, is connected in line with a capacitor of 200 microFarads and a resistor of 12 Ohms. The circuit is supplied with an alternating current of...

Homework Statement A 50 cycle alternating current has a maximum value of 42.42A . It crosses the time axis in a positive direction when time is zero. Determine (a) the time when current first reach a value of 30 A. (b) time when current after having gone through its positive maximum value.

Hello I read on Wikipedia that alternating current periodically changes direction. So if it keeps going backwards and then forwards how does the charge get around the circuit? Thanks

Homework Statement for a generator in a series alternating current circuit, the phase relationship between the generator voltage and current in the generator is? Homework Equations N/A The Attempt at a Solution the current is at some angle theta relative to the voltage.

Hi, recently I've bought a printer with its input voltage of 110V. Well, my home provides 220V instead, so I started thinking about getting a transformer. The printer specs (HP P1005) says that: Required input voltage: 110 to 127 V (±10 percent), 60 Hz (±2 Hz), 7 amp Power consumption...

How to use complex number in the alternating current circuit?

Homework Statement I need to find the magnetic field a distance r from a long, thin wire carrying a current I(t) = I_0 \sin \omega t.Homework Equations Field a distance r from a wire carrying a steady current I in the z direction: \vec B(r) = \frac{\mu_0 I}{2 \pi r} \hat \phi The Attempt at...

Can someone please explain how the current regularly changes direction after some time in alternating current? I mean if it changes direction, how does it move forward?

Does a current need to change direction in order to be considered as an AC? What if the direction remains the same, but the amount of current which flows varies with time, as in a sine wave? Thanks

at the subatomic level, what happens when ac flows?

Can someone explain to me how power sources (e.g. power plants) transmit current/electricity in a sinusoidal (AC) behavior? At different parts of power lines there are transformers that drop voltages so ordinary appliances can operate correctly. Is there some kind of device that converts...

I understand the basic difference between "direct current" and "alternating current", but can someone explain to me why most appliances require the use of alternating current (that is why power plants emit AC to our outlets) instead of direct current? I mean it makes sense if appliances have...

Homework Statement in figure shown below, a lamp load taking 6A and a single-phase motor taking 4A from 120v/60Hz source. the current to the lamp load is in phase with the voltage and the current to the motor logs 50 degrees. determine: a) value of total current IT (rms) b)angle by which...

I was just thinking about batteries and such after my brother asked me about AC vs DC current and their pros and cons.

Homework Statement On its highest setting a heating element on an electric stove is connected to an ac voltage of 240V. This element has a resistance of 29 ohms.(a) Find the power dissipated in the element.(b) Assuming that three-fourths of the heat produced by the element is used to heat a...

Hello there my fellow chemical structures! I was just wondering the other day, while staring vacantly at a lighting fixture: How slow would the AC going back and forth through the light bulb have to be before you could see it flickering? Any information would be much obliged. Thanks in...

Homework Statement The peak value of an alternating current in a 1500W device is 5.4A. What is the rms voltage (root-mean-square voltage)across it? The Attempt at a Solution Peak current=sqrt(2)*Irms 5.4A=sqrt(2)*Irms Irms=3.82A Irms=P/Vrms 3.82=1500/Vrms Vrms=392.84V I am not sure...