Charging Definition and 407 Threads

I'm trying to solve this: E = R\frac{dQ}{dt} + \frac{Q}{C} from here http://physics.bu.edu/~duffy/semester2/c11_RC.html You might recognize this as the charging equation for a capacitor I'm guessing I need to try and get (1/q)dQ or similar somewhere to get the lnQ but I cannot seem to get...

Homework Statement A 1234. pF capacitor and a 5.6 × 106 ohm resistor are connected in series to 78. volts EMF. Approximately how long does it take the capacitor to become almost fully charged? Homework Equations Vf=Vo(1-e^(-t/RC)) The Attempt at a Solution I'm not sure if the...

Homework Statement When a does a capacitor increase in charge linearly? Homework Equations C=Q/V The Attempt at a Solution If I am correct, it is when the capacitor is being directly charged by a battery. When there is a resistor, we get an RC circuit scenario where capacitor...

The questions says an isolated conductor has charge Q ... is isolated the same as uncharged ? If so , how can it have charge Q ? Also , if an earthed conductor is brought near a positively charged capacitor , some of the negative charges will move to the +ve charged capacitor and vice...

1. Capacitors C_1 = 13 uF and C_2 = 26 uF are each charged to 20 V, then disconnected from the battery without changing the charge on the capacitor plates. The two capacitors are then connected in parallel, with the positive plate of C_1 connected to the negative plate of C_2 and vice versa...

1. The switch in the figure has been closed for a very long time. A.) What is the charge on the capacitor? B.) The switch is opened at t = 0s. At what time has the charge on the capacitor decreased to 12% of its initial value? 2. Q=VC, tau= RC, etc. 3. A.) The capacitor...

I am trying to derive the mechanism of a charging capacitor , V=Vo(1-e^(-t/CR)) sorry , i couldn't upload the diagram here so i will briefly describe it , its a circuit with a battery (Vo) , connected to a capacitor (Vc) , and resistor (VR) and also a switch , all in series . i started...

[b]1. First you fully charge a capacitor (C = 6.4 µF) with a 12V battery. Then you disconnect the battery and discharge the capacitor through a resistor (R = 3 Ohms) and an inductor (L = 2.0 x 10-3 H) in series. [b]2. What is the charge on the capacitor when you begin discharging at t= 0...

Grounding is used for dircharging.. In case of charging by conduction,let a sphere having excess negative charge is brought in contact with a neutral sphere..Half of the negative charge goes into neutral sphere..But when the former sphere having excess negative charge is grounded,why it becomes...

I've got a 12V1.3AH/20HR battery and I tried charging it with my 12V solar pannels of 200mAh max output together (2 solar panels with 100mAh max designed for charging car battery trough cigarette lighter thing) but the solar panels their lights wouldn't go off meaning no power were given to the...

When a charged body is brought near an insulator, the side facing it acquires a charge of opposite sign because of induction. Is it possible for an insulator to acquire same charge as charged body? (by induction, touching or any other means)

Homework Statement I have a question that has been puzzling me: I know that when we bring a negatively charged rod close to a neutral metallic sphere, the negative charges are distributed to the opposite side of the sphere because of the negatively charged rod and the positive charges remain...

I have 23 450V 1600uf electrolytic capacitors and was wondering if I could use them in a series? If I were to put them in a series, would they act like a single 10,350 volt 72.727 uf capacitor? Or would they melt/fail/leak/explode if I tried to use them that way? Any information is helpful! Thanks!

Ok, I'm not sure if this is the right place to ask, but similar other posts are here. I'm a little rusty with my electronics (I used to tinker back in school, but not so much now) So here's the deal, this is an automotive application. I have my truck which has a 1100CCA 12V battery and...

I want to charge a single lithium-ion cell from a current-limited voltage source. My "black box" (or rather, it's white -- with a question mark inside) has inputs of ~250mA @ [3.7V to 5.4V], and target output (i.e., the lithium-ion cell) of 3.2V to Vch = 4.2V. Which means: I can't charge the...

Hello, I am designing a circuit that will be running off of two AA rechargeable (1.2V 2500mAH NiMH) batteries that are stacked in series, and I am looking into a way to charge the batteries in-circuit rather than having to take them out and charge them externally. I did a very brief search...

This is a two part question. I completed the 1st part, but I am having a difficult time on the second part. I have one try remaining. Magnetic Field and Poynting Flux in a Charging Capacitor- When a circular capacitor with radius and plate separation is charged up, the electric field ...

So, I'm really confused on how a capacitor gets charged. I understand that electrons from the negative terminal of a battery flow to one side of the plate to make that side negative. However, I don't understand how the positive plate is formed. From what I've been reading, it says that...

Other than a power box which can be incredibly expensive, can someone show a good way to charge a capacitor in the 300-450 volt range, and as i am designing a circuit around multiple capacitors would i connect them in series or parallel, and yes they are polarized

Dear Gurus, o:) I bought a pair of AAA nimh batteries rated at 1.2V 900mAh. Fast charge can be done in 5 hours @ 270mAh. Standard charge can be done in 15hours @ 90mA. My doubt is assuming both batteries have different impedence, can they be charged in Series at say between 1.4v to 1.6v using...

In a simple RC circuit, where you have an ac supply attached to a capacitor and a resistor in series, during the positive cycle the capacitor starts to charge and it will reach a certain percentage then during the negative cycle the capacitor will start to discharge through the resistor. Will...

Homework Statement We are examining an RC circuit with a scope. A square wave is applied to the circuit. Sketch the square wave and the trace giving the voltage across the capacitor. Explain your results. The Attempt at a Solution So I got something like this. Now the way...

Homework Statement A cordless drill battery charger is rated at 30.0 W but requires only 13.5 V. It contains a transformer that converts 120 V household voltage. (b) What is the current in the secondary coil while the battery is charging? (c) What is the current in the primary coil...

Homework Statement In an RC circuit under charging, does the current actually flow across the plates of a parallel plate capacitor? Does charge emanate from both terminals of the battery and move to the plates of a capacitor or does charge only emanate from positive terminal and get...

Homework Statement A 50 \muF capacitor is being charged from a 6V battery via a 100k\Omega resistor . what is the initial charging current? after a period of time, the charging current is 30\muA. what are the pd's across the resistor and the capacitor at that moment? how much charge has been...

Homework Statement Here is a pretty straight forward question, i just wanted to double check my answers (in bold!) This problem explores the behavior of charge on conductors. We take as an example a long conducting rod suspended by insulating strings. Assume that the rod is initially...

My doubt is that when we charge a battery we say that energy is transferred into it , but does the emf of a battery change in this process ? Is the emf same before and after charging , if yes then what actually happens during charging a battery ?? pls help !

Hello, This may be a very basic question regarding the workings of accumulators, but I have been unable to find the answer elsewhere. If the pressure and flow within a hydraulic system is varying sinusoidally (peak pressure = 200 bar, period = 10 s) due to the motion of a piston, and you want...

I just ordered a DC to HV DC converter (the F40 model, datasheet here: http://www.emcohighvoltage.com/Fseries.PDF ) from eBay for $50. My intent is to charge capacitors such at the 400V 12,000uF one located here http://www.amazing1.com/capacitors.htm. The converter has output up to 4,000V...

when we say batteries create the potential difference between the two ends of the capacitor..what does it mean?how are does a plate become negatively charged and positively charged?please explain

Homework Statement Image URL: http://img13.imageshack.us/img13/1935/capacitor.png Before the switch was closed, Capacitor 1 had a charge of magnitude CE/3 on its plates and Capacitor 2 had a charge of magnitude CE/6. The third capacitor was initially neutral. Find the charge flown through...

I have a red top optima battery like this in my truck: http://www.optimabatteries.com/optima_products/redtop/specs.php" I don't drive this truck very often so it looses power after a while. I'd prefer not to disconnect my battery and loose the memory in various electronics. so i bought a small...

This is close enough to a homework question so I've put it in this section, though maybe it should be posted in the EE section. I've been looking at the equations for boost converters today, and I'm interested in the problem of how long it would take a bank of capacitors to charge through an...

This isn't homework, but it feels like it...it's from the Dorf & Svoboda Introduction to Electric Circuits, 6th ed. on p 298, if you happen to have that. I'm following the derivation of the formula for capacitor voltage for an RC circuit with a single resistor and single cap, or the current...

hi all, i have this qns which i been figuring, but can't get the right circuit. i have 2 12v batteries. which i want to wire in series to give it a 24v starting to a motor. however by doing that, i am unable to charge both batteries as my rectifier is only able to charge 12v. I need to...

Hey guys, I recently conducted an experiment which involved charging a battery via a PV module and also logging the I and V values to calculate conversion efficiencies. I also logged the I and V values from two other circuits with a fixed resistance. I understand that every irradiation has a...

Why don't we simply take t as x? why is it t? Where is the time constant. If you're looking at a question mark instead of the symbol "tau"...you know its tau.

How does current flow across a capacitor? When a cap is charging up, the current is high initially and then gradually decreases as the charges start to build up on the plate of the capacitor. I can't figure out how current flows from one plate to the other? Its not like a resistor, where...

The P.D of a charged capacitor should be more than the charging source... That's cause the charge felt by the cell on its terminals might be less that the net charge (depends on what level of charging is the capacitor in), as a result charge accumulation continues until the plates are saturated...

Homework Statement Describe the steps in charging a single object by induction (using grounding) if the charging object is positive. Homework Equations N/A The Attempt at a Solution We've had to do explanations similar to this before during class; however, never with a positively...

the source is 120V DC with an internal resistance of 40 Ohms. the battery's emf is 10V with an internal resistance of 1kOhms. what can i add to the circuit to improve the charging time (faster charge)?

the source is 120V DC with an internal resistance of 40 Ohms. the battery's emf is 10V with an internal resistance of 1kOhms. what can i add to the circuit to improve the charging time?

Hello. I am currently trying to evaluate just how much power the external RC circuitry of a 555 timer uses over 1 cycle. Whilst the capacitor is charging the current falls exponentially. Naturally the voltage also falls through the resistors but this is couteracted by the rise in voltage of the...

Hi Guys, :smile: My mobile phone battery was completely drained and so I put it up for charging. However, inspite of the charger providing charging current to the cell phone, the phone shut down several times indicating ‘Battery Low’. As per my understanding, the charger charges up the...

A parallel-plate capacitor of capacitance C with circular plates is charged by a constant current I. The radius a of the plates is much larger than the distance d between them, so fringing effects are negligible. Calculate B(r), the magnitude of the magnetic field inside the capacitor as a...

I've started an experiment lately with charging a capacitor through a resistor, I wanted to prove that the equation of charging capacitor by using linear law, but it didn't quite work and needed help. This is what I've done: Equation of charging a capacitor: V = V_{max}(1-e^{\frac{-t}{RC}})...

I got some guy who says when a capacitor is fully charged, that half of the input energy from the power source gets lost as heat. Now I do understand the two cap problem (links below), but I think he is wrong because one can use dc switching and inductors to improve the 50% loss of energy. (but...

Homework Statement A 4.6 mu or micro FF capacitor is charged to a potential difference of 15.0 V. The wires connecting the capacitor to the battery are then disconnected from the battery and connected across a second, initially uncharged, capacitor. The potential difference across the 4.6...

Homework Statement A parallel plate capacitor is changed to an electric potential of 334V by moving 3.78e16 electrons from one plate to the other. How much work is charging the capacitor? Homework Equations Delta V= Delta PE/ q c=q/v The Attempt at a Solution Delta V= Delta PE/ q...

I am trying to charge a battery using wind power! but i can't seem to find anything telling me how i can determine the power output coming from the generator, when all i know is the wind speed.. i know that the blades on the fan will have to be small but using the right gears with the high speed...