Ac Definition and 1000 Threads

Why is it that AC is superior to DC in long distance power transmisson. I was thinking it has something to do with the resistance of copper wire but if this is the reason then why is that? Or, why is copper loss not a factor with AC current? Thank you!

Now this is not a homework question, just a practise question and my answer doesn't match. An AC source of 200 V rms supplies active power of 600 W and reactive power of 800 VAR. The rms current drawn from the source is ? (the answer is 3.75 while mine is 5) I did was squared and added the...

so the reason why alternating current is used to deliver energy to households is because for a given wire, the voltage drop is always less with ac rather than dc right? but when i calculate the voltage drop it coumes out to be the same! v=IR R=P(length of wire)/(cross section area of wire) i...

In DC circuits the charge carriers move uniformly through the entire cross sectional area of the wire. In AC circuits the current is constrained to travel in a thin "skin" just below the surface of the wire, effectively reducing the cross-sectional area of the wire. The effect becomes more...

I just don't understand how it does, because I never noticed the terminals change positions. I understood how DC generators work, but not AC.

Homework Statement R=250 L=6 C=15microf e(t)=300sin(50pi t) Find Z, phase angle, lead/lag, emf(215ms) (got all of this right) Voltage across inductor, capacitor and resistor, also show that the sum of the voltage across the elements at 215ms is equal to total emf at 215ms. Homework Equations...

Homework Statement For the circuit below (attached) plot the amplitude of AC voltage across resistor as a function of the angular frequency of the ac source. Homework Equations ZR = R The Attempt at a Solution I'm not really sure about any of this. Across the resistor, the complex...

Hi all :) As the title says how do Ac and DC affect the body differently? Also if anyone knows the answer to these questions as well I'd REALLY appreciate it :) 1.How electric current and magnetism interact 2.The effect on frequency on the impedance of a capacitor and the impedance of an...

I am currently looking into using a master magnet to separate aluminum from food products by AC induction. First, does anyone know if this would be at all possible? I know that recycling companies use Edy machines which sound like the same process of seperating cans from other materials. I am...

I have an AC Gearmotor W/Fan, Base Mnt, 100 rpm, 7 in-lbs Torque, 115 VAC - I need to achieve 2 purposes with it: 1. Need to able to reverse directions - can I do it with a DPDT? 2. It is overheating - how can I solve it -- heatsinks or fans? Any recommended ones -- I have never done that...

Hai, I have the following circuit: http://img152.imageshack.us/img152/1848/powertransfer.png My task is to calculate the power dissipated in the resistor, and also the power delivered by the V1 source. Here's what i tried. First i /dev/null'ed the second source and calculated the...

Homework Statement An electromagnet is placed next to a coil of wire. According to Lenz’s law, what will be the direction of the induced current in the resistor R in the following cases? a. the magnetic field suddenly decreases after the switch is opened b. the coil is moved closer to the...

Hello all! I must design an ac ammeter which uses successive approximation ADC,has a specified voltage of 0,15V and individual entrance resistors for measuring currents of 200mA,500mA,1A. Any suggestions on how to build such a device would be highly appreciated!

Which is most dangerous for human being 230 V ac or 230 V dc voltae supply

Which would be more dangerous for a human being 230 V a.c or 230 V dc supply...

Hai Guys... I want to check the AC current by using digtal multimeter.Please give me instruction.

Hi all, i am working on an 110W inverter (Dc to AC) project that the input voltages varies from 700Vdc-1000Vdc and the output voltage is 220Vac. The system operates, however i have problem with output choke. The output choke temperature increases instantly even in no load operation. My...

Homework Statement Given resistance of circuit 68 W, I(max) = .191 A, V(max) = 22.5, what is the average power of this circuit? Homework Equations P(avg) = I(avg)V(max) The Attempt at a Solution I took .191 and divided by sqrt(2) to get the rms current and multiplied by the max...

Is it bad to replace a regulated AC adaptor that has an output rating of 9V DC and 200mA with a regulated AC adaptor of the same polarity that has an output rating of 9V DC and 1.7A? I know it's OK for the current rating to be higher than needed, but in this case the current rating on the new...

Homework Statement Explain why A.C. is used instead of D.C. to transfer electrical power from the generating station to the consumer. Homework Equations The Attempt at a Solution To reduce the energy lost in long distance transmission. To reduce costs involved in transferring...

In parts of Brazil, the mains voltage is 127V AC. Is it safe to use an appliance which is supposed to take 117V AC in this situation? Thanks

hi, im looking to connect a 230V AC to an 4V LED. i was suggested a thyristor could be used then a rectifier to convert AC to DC then using a resistor to drop the voltage to 4V. i dan't seem to understand how a thyristor can aid this process. Any suggestions, please help?

Hello, How can I use an electronic device that takes 240V AC in an area where the power supply is 127V AC? Clearly I need a step-up transformer, but the only ones I can find convert 110/120V to 220/240V. If I use one of these, will it convert 127V AC to 254V AC (twice 127V)? If so, would it be...

Please see the attached illustration. This is clearly an open circuit. The voltage source is producing a voltage at some amplitude and frequency. If one were to measure with an oscilloscope the potential difference at the point where the mouse pointer is with respect to the ground, what would...

Fact: If A and C are subsets of R, let AC={ac: a E A, c E C}. If A and C are bounded and A and C consist of strictly positive elements only, then sup AC = supA supC. I am trying to understand and prove this fact, and this is what I've got so far... A, C bounded => supA, supC exist (by least...

I know this can't be done but I don't know why. It's been established that the Axiom of Choice is required to prove the well ordering of the reals. Why can't we say that for any pair of real numbers a,b in the set R there exists a Dedekind cut that falls between a and b such that always a>b or...

A 9.7 Ω resistor, a 10.8 µF capacitor, and a 27.9 mH inductor are connected in series with a 120 V (rms) source with variable frequency. (a) At what frequency will the current be maximum? Hz (b) Find the maximum rms current. A (c) Suppose you now replace the 10.8 µF...

I recently acquired by accident a 750 watt DC to AC power inverter, designed for powering AC appliances off of a car battery or other 12V power source. I have no need for such functionality. I am really interested in high voltage projects and I was wondering if there are any interesting...

I recently acquired by accident a 750 watt DC to AC power inverter, designed for powering AC appliances off of a car battery or other 12V power source. I have no need for such functionality. I am really interested in high voltage projects and I was wondering if there are any interesting...

Hi Experts, I would like to make an electronic circuit to control AC power to switch on and off a light bulb based on sensor. Being new to this , i hope know what aspects i need to pay attention to when using DC to control AC? sincerely Ramone

Hey guys, I am new here and had a question. I currently have a 1 V peak (2 Vpp) AC wave coming into my system and I want to find the most efficient way to convert it into DC. A simple bridge wouldn't work for me because too much of the voltage would be dropped across the diodes. The system...

Homework Statement A Purely resistive resistive 100w, 110v lamp is to be supplied by an a.c. source of 230v r.m.s at 50Hz. what value of pure capacitance could be put in series to adjust the current flow to a suitable value? Homework Equations p=iv q=cv v=ir i know a number of other...

Getting powers from Ac Circuit Homework Statement Hi guys,, need help with the following question : The Attempt at a Solution OK, first things first ,, what does the question mean by saying ?? and I know that real power equal I^2 R for series & V^2/R for parallel but the problem it...

Homework Statement A resistance R and a 1.4 H inductance are in series across a 60 Hz AC voltage. The voltage across the resistor is 30V and the voltage across the inductor is 40V. (a). What is the resistance R ? (b). What is the AC input voltage ? Homework Equations \xi=I*Z The Attempt at...

Homework Statement If A and C are subsets of R, let AC={ac: a E A, c E C}. If A and C are bounded, prove that sup AC = supA supC. Homework Equations The Attempt at a Solution I acutally think it's not always true, for example when A and C each consists of only negative numbers. If A...

good / bad ideas: 1. have an extra fridge. small 170 litres. can i use it like an ac - cool the room? switch it on and leave the door ajar? 2. buy five-six 15x15 feet white canvas, put it on my roof. put 2-3 buckets of water on roof. canvas acts as a buffer between main roof and sun. water...

How do you express impedance in terms of w(omega), R, L and C knowing the circuit diagram. I understand that for R Z=R L Z=iLw C Z=-i/wC What is the effect of having components in parallel/series, could someone please give an example of a circuit and it's impedance expression...

Homework Statement I was assigned to design an ac ammeter.But i have no idea how to work on it and don't know how to find the R for the ac ammeter? Thx for the help! =] Homework Equations The Attempt at a Solution

can someone please explain to me physically how is it that when i have an AC source and i measure Voltage on a resistor its the same with and without the resistor and when i have a DC source and i measure Voltage again on the resistor and now there's a different reading its like ohm law...

Homework Statement What is the resistance between terminals AC? What is the resistance between AD? An underground telephone cable, consisting of a pair of wires, has suffered a short somewhere along its length (at point P in the Figure). The telephone cable is L long, and to determine...

I have a question about how much power I’m using to run a LED light that I modified to run off an AC-DC adapter instead of 3 AAA alkaline batteries. The light is a Sylvania Lighting Dot It Black Led Swivel, which uses about 1/4 of a watt (4.5 V X 54.7mA) on batteries. The light would dim...

What does it mean when you put on a AC voltage source (~) 50/60º. The book I've been studying from says the rms or peek voltage only. Thanks.

Hello, I've recently read a couple of things about brushless motors that have spurred quite a few questions. Googling has solved some of them, but I'm hoping that you can help with the rest :smile: Apparently there are two types of permanent magnet brushless motors - DC and AC. This is...

Hello to all, I'm a student of electrical engineering. We have learned the basics about AC induction motors and we learned that single phase motor cannot start by itself. There must be some additional part that will produce phase lead or lag in order to create rotational magnetic field. That...

We have adapted a 60W A/C Fan Motor, 1500 RPM to run two spindles one at 6000 RPM and the other at 500 RPM using pulley & belt. On continuous use the motor heats up excessively and a few fail. Load is winding of threads from a Cone to a bobbin. I need a few suggestion i) Can rewinding...

I am trying to determine the power requirements for an AC Motor for a Plunger type wave maker. Attached is the layout of the plunger and tank. The formulas that I think might be involved in solving this problem are below: P.E = mgh W= F x d Power= W/time Pressure= F/ area What I...

Homework Statement two alternating currents I1 and I2 flow into a circuit node,the output current I is given by adding I1 and I 2. find I and t, when I1 and I2 are as follows Homework Equations I1=5sin(50t +Pi/3) I2=6cos50t The Attempt at a Solution...

Hello All, I've been playing worth some DDS output filter and amplifier circuits in the simulator and have run into an interesting little problem. I want to make an output that can range from 0.2Hz to 20Mhz and so far I have built a very nice reconstruction filter that can give me a very...

Can someone give me a circuit diagram i can use to change the frequency of AC current?

There are two AC current carrying conductors.(both are of the same frequency) How do you compare the currents to know if they're not equal at all times...? Please Answer as soon as possible ...