# What is Ac: Definition and 1000 Discussions

Michal Áč (born 17 May 1985) is a Slovak football defender who is currently plays for FK Janíkovce.

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1. ### Can I twist the Connecting cable with the Connecting pipe?

Hello, I bought AC, so I need to connect a copper pipe and electrical wire from the indoor unit to the motor. Can I twist the connecting cable(electrical wire) with the connecting pipe(copper pipe)? Is it safe?
2. ### I have a few questions about refrigeration and AC units

I have a few questions about how fridge and AC work, i didn't know where to open this thread, i hope this is ok. So from what i learned so far, both work in a similar way, effectively moving heat from place #1 to place #2, in effect, "cooling" #1 and heating #2. The main difference (apart from...
3. ### Condensate flow and mold in mini-split ductless AC indoor unit

My AC has begun to emit a rather foul smell, which has led me to geek out on the inner workings of its indoor section. For example, how does the condensed moisture make its way to the drain pan? I am assuming that the condensation happens on the fins of the evaporator. But in that case, what...
4. ### Power Fluctuations in our AC Mains Power Generation Facility

I am currently at a power plant here in Texas and the 480VAC system swings from 480 while equipment is on line and as high as 536VAC when equipment is off line. They tell me that this is prefectly normal but I have never seen swings like this at any power plant. So, is this normal???
5. ### B The historical war of currents in Mains Power Distribution: AC vs DC

So, if I get it right, the basic argument goes like this: AC was preferred to DC because its voltage can be stepped up by a transformer. This limits losses while the current is transported from the production plant to the final user. The voltage is subsequently stepped down when delivered to the...
6. ### Powering My AC Mains Project with a Push-Button Timer

Hello! I am trying to create a special kind of switch for a project I am working on and I am pretty stumped. Basically, I need to power a 110v fan and light for around 10 seconds with the push of a button, and then have them all turn off and be ready for another button push. My brain immediately...
7. ### Rectifier circuit for AC sources with 180˚ phase offset

In a simple 2-phase generator that I am making, I have 2 pairs of oppositely placed copper coils in arrangement similar to this: I would like the generator to power DC devices. My question is: How could one rectify the output from opposing coils? Or, in other words, how could you rectify 2 AC...
8. ### Magnets with Halbach array in an AC generator

As a project, I am demonstrating electromagnetic induction by making an AC generator. The magnets I currently have access to are very strong neodymimium countersunk magnets, but I noticed that they utilise a Halbach array. I am aware that this means the magnet has alternating N-S poles spaced...
9. ### Step down transformers used in residential AC Mains distribution

Hello, If we have a pole top mounted distribution step down transformer for residential use what happens to the voltage on the secondary side if the primary side voltage increase? Thank you
10. ### Engineering Use voltage nodal analysis to solve for the current flowing in this AC circuit

Hi first time using this forum, I have some homework that I am entirely stuck on, can anyone help me with this question? I understand the placement of nodes, and that I need to convert complex numbers, but apart from that I have no idea what direction that I'm supposed to take in this. I don't...

12. ### AC Mains Transmission Tower question

Hi all. Many of you on the forum seem to be very knowledgeable on power transmission. I often notice transmission towers like this on. I know the three large wire groups are the three phases of the AC power, but the towers often have two smaller wires (red circle) on the top. Sometimes they...
13. ### A AC Stark shift in diatomic molecules

Hello! I am analyzing data from a diatomic molecules with a rotational constant around ##0.2## cm##^{-1}##, for transitions between rotational levels between the ground ##^2\Sigma_{1/2}## and excited ##^2{\Pi}_{1/2}## electronic state. I was wondering if there is a way to approximate the shift...
14. ### Biot-Savart equation for AC current

The fact that the current changes in time should allow me to take it outside from the integral along the coil, since it is not a function of space. But I'm not sure about this assumption, is there something I'm missing or am i correct? Thanks
15. ### Leakage Flux Inside a Slot of an AC Machine (dual stator)

Hello All, Please see the attachments. The pdf file is the IEEE paper I'm reading. Figure 1 show a slot of the AC machine similar to the front view of the picture below: But in one slot, they fit two sets of conductors. The first set carries current i1 in total. The second set carries...
16. ### What does the 'power' vs 'time' graph look like for a 3 phase AC supply?

Hi, For years I wanted to understand why we have a 3 phase supply and not a 2 phase supply in AC. In Quora I found an interesting answer and was convinced about the purpose mentioned: Answer to Why there is no two phase electrical inputs instead of three phase and single phase? by Paul...
17. ### Investigating Why a Century AC Motor's Label Shows 1625 RPM

Hi great folk I have a Century AC motor which is ¼ HP, 115 V, 60 HZ This is a Permanent Split Capacitor (PSC) motor It has 4 poles, so the running speed according to the motor equation should be: . Speed = 120x60 / p …………….. Where P = number of poles Therefore RPM = 120 X 60 / 4 = 1800 ...
18. ### Could you use Solar to power a DC to AC Inverter? (Description below)

I'd like to take Solar Panel power output and use it to power an AC outlet on the ultra-cheap. I know a lot of people use Solar to connect to a purpose built inverter and also have a battery somewhere in the mix to provide a stable output but wondering if the following (using the assumptions...
19. ### Choosing pulse capacitor for parasitic AC ripple suppresion

So long story short I have a power supply (DIY) for some time and on the secondary side filter/reservoir capacitors there is a small ripple (about 1v PP) of 50khz (the switching frequency of the PSU). Aside from others methods that I will implement to reduce this I am thinking of adding a shunt...
20. ### Subtracting AC Voltages for Audio Amp Simulation

I am studying the calculations made for small signal amplification with in the web article http://www.ecircuitcenter.com/Circuits_Audio_Amp/Basic_Amplifier/Basic_Audio_Amplifier.htm. I have created the simulation for the basic amplifier in Ltspice (attached) I'm having a problem finding the...
21. ### Understanding AC Motor Basics: Why a 120V Motor Can't be 3-Phase

I have just started my electrician career and I am studying electric motors. why an 120v ac motor can not be 3 phase ? .
22. ### AC Drift Velocity: Understand Reactive Power & Movement of Electrons

Hi All I hope this topic makes sense for this forum and somebody can help me to understand. This is what I understand (please allow numerical approximations): 1. Electrons move in a conductor at a speed anywhere near the speed of light. 2. Electrons gain actual velocity (drift) only when...
23. ### AC circuit power formula question

im kinda confused on why can't you just use the formula P=I^2R. Can you just use Vrms or Vamp (not sure which one is it) and the value of R which is 105Ω to solve for I Then just plug it in the formula P=I^2R. But when i did that it the wrong answer so is this formula don't work for AC...
24. ### Impact of AC effects on current density analysis of pcb for 50-60Hz

Hello , I was looking into current density analysis of a PCB that handles distribution of AC power . from ansys and cadence sites , i realized by current density they refer to DC IR drop that is a pure ohmic analysis that doesn't take into consideration the AC effects . And in order to take this...
25. ### Determining inductive reactance from a 3-phase AC circuit

I am trying to figure something out, but I am in the first step and just trying to get through my "thought experiment". Let's say I have a 480V 60hz 3 phase supply feeding a circuit that comprises of nothing but the conductors themselves (effectively a shorted power supply). Consider the...
26. ### High Pass Filter Working Principle

A few days ago, I learned to make an AC to DC converter. One question is troubling my mind. How does a High Pass Filter Capacitor work? Going through some websites I got a sketchy idea. As the current after passing through the bridge rectifier comes to capacitor, the capacitor starts charging...
27. ### AC circuit analysis involving resistors and inductors

Summary:: Hi anyone can explain me how to solve this circuit, finding the current I2 and I1? Really don't know where to start Thanks
28. ### Engineering How can I find DC gain via AC simulation in LTspice

I use this netlist and simulation result came out as shown. I need to find the dc gain here and circuit diagram, but I'm not sure how. I would be very grateful if you could give me the answer.
29. ### Current vs. Time in AC Current

I always find voltage vs time majorly in case of AC current. What about current V time in AC current cases?
30. ### Engineering Applying Thevenin's theorem to AC circuits

So I've seen other threads on here with the same problem from a few years ago, and I'm just not getting the same answers. However, I followed along with a similar problem in the textbook and used all the same methods, so can't understand where I've gone wrong, or if I even am wrong. Also not...
31. ### Engineering Calculating Power Losses in an AC Induction Motor

Given the AC Induction (asynchronous motor) in 3 phases: Parameter Value Pn (Nominal Power) = Pmechanical (output power at the shaft) 5 kW = 5000W uls (Voltage through the stator line) 220 V fstator (stator frequency) 50 Hz p (Number of pole pairs) 2 LFe (Iron loss) = Lmechanical...
32. ### Engineering Maximal effect in an AC circuit

Hello again, I have a solution for the question, but as it is my first time solving these types of exercises I am uncertain if I my solution is correct. The first picture represents the exercise with the circuit and the second is the just some rewrites of the circuit, in swedish. Picture 3 and 4...
33. ### Engineering AC Circuit Phasors: Find I1, I2, I3

Summary:: Hi, I tried attempting this problem in alternating current in order to find out the phasors as complex numbers, and I would be more than grateful if someone could peer review it, and confirm my calculations (Please see below both the Figure and the calculations) Please find attached...
34. ### Engineering Active and reactive effect in AC circuit

Hi, I am once again asking for help regarding a AC circuit problem. This time I need to compute reactive and active effect for z=R2+C3 in the below circuit. I have already computed u(t) from before so that solves half of the problem. I am unsure if I have done the calculations correct, not much...
35. ### AC power loss in lossy dielectric (capacitor) with DC-bias field

Hi there, if a dielectric (capacitor) is described with a constant permittivit eps (or C) and loss-tangent DF, how much energy ist lost when charging the capacitor by 1V? For example: C=1, DF=0.1. When charging from 0 to 1V, the lost energy (in J) is ...? When charging from 1V to 2V, the lost...
36. ### Digitize AC Voltage & Current Signals - Solutions for Split CT

I am looking to digitize AC voltage and current signals that are measurements from my breaker panel. Any thoughts on what could be used to digitize the AC current? This current would be coming from split CT.
37. ### Analogue Circuits Question -- AC and DC currents through a coil

Summary:: . Hi ,so am currently doing homework , and was wondering if anyone could tell me if i have done my calculations correctly ,because am not 100% sure that i have answer to those 2 questions correctly .If i have went somewhere wrong if you could tell me where and how i could fix it...
38. ### Engineering Understanding Resonance in AC Circuits

Here's my attempt at a solution.

40. ### Engineering How to deal with dc source on ac circuits?

We are tasked to solve for the steady state voltage v using superposition theorem. I start with solving with voltage source using mesh analysis and got the current flowing through the 3 ohms resistor and get the first value of the voltage which is 3.2cos(6t+126.87). Now my problem is I am...

Summary
42. ### Induced EMF in a small square loop of wire at center of an AC Circuit

I used the voltage of the power supply and resistance to solve for the current in the larger circuit (20V/5ohms=4 amps). I am not sure if the equation listed above is the correct one I should be using, but I tried it using the following numbers. For omega, I used 2*pi*frequency. N should...
43. ### Comparing DC to AC: Is A Always Correct?

https://www.physicsforums.com/attachments/282071 https://www.physicsforums.com/attachments/282072 If the question changes DC to AC, the correct answer would be just A right? The reason why (B) and (C) are wrong is that the current keeps changing direction and doesn't remain constant throughout...
44. ### DC versus AC current in a coil

Hello, am kind of new to all the physics stuff , and kind a terrible at maths but am trying my best to be good at it one day .So i was told to answer this question When a direct current of 2A is passed through a coil, the potential difference across the coil is 20V. When an alternating current...
45. ### Choosing pneumatic solenoid, AC or DC

Hi There are mixed information on these on google. I want speed(low lag) first, valves will be open and closed 1-2 minutes. Controlling them with Arduino or ESP with relays. Do I get this right? AC 220 - controlling them with Solid State Relays + Speed of Solenoid with AC is faster than DC +...
46. ### Circuits - AC circuits / phasor

Hi, my school has no answer key provided. and would like to check if this is correct. Thanks!
47. ### Engineering Transfer function of AC Transformer

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...
48. ### Which Formula Should I Use for Calculating Power in an AC Circuit?

Should i use P = V.I or P = Vrms.Irms.cosφ ?
49. ### How does smoothing an AC voltage with a capacitor work?

Specifically for part (i) and (ii), I get the rough idea that when the voltage of the AC source is decreasing, the capacitor can discharge to "cushion" the drop in voltage. However, I have some questions about when this occurs. 1. There is an assumption that the capacitor will be charged to...
50. ### Understanding Voltage Distribution in AC Circuits

The problem is shown below: (I am only asking about part b) ^Above is the problem. Below is the solution to part b. They have claimed that we can set potential at C = D = u(t), and A=B=0. Why is this claim true? What I realize: By applying Kirchoff's across ACDB, Voltage across C1 = Voltage...