Battery Definition and 1000 Threads

Homework Statement I realize I actually don't understand the concept of a battery (potential difference) and a capacitor. From what I know a battery is something that provides a "drive" for electrons. In other words, take a 90V battery for instance, that just means 90J/C, which means it...

Homework Statement I have this circuit: http://img59.imageshack.us/i/doublebattery.png/ Homework Equations what are the currents I1, I2, and I3 and the power being delivered on each resistor The Attempt at a Solution i've tried doing 3 equations using the kirchhoff rules but i...

hello i need some explanation on this . I know that when a battery is connected it provides constant voltage across the capacitors. But the happens when the battery is disconnected. What happens to the voltage, the capicitance, and what is the importance of dielectric. I have read the book...

What should be the voltage across a 9.7 volt battery pack when it is in use (discharging)? I used a multimeter to check that and got the reading as 5.8 V. It reads 9.4V when not in use. From my knowledge, a battery is a constant source of e.m.f. But the above observation is weird. What is the...

Homework Statement A car battery with 12V EMF charged to 120amp hours. Assume potential difference across terminals is constant. How long can the battery deliver energy at a rate of 100Watts. Missing is current (i), internat resistance (r), and real voltage (Vr)Homework Equations (Amp...

I am trying to invert the the output of a battery so I can run an op-amp double ended with 5 volts and -5 volts. The battery itself produces 7.5 volts so I am passing it through a linear regulator to drop it down to 5 volts with low noise, at the expense of heat/efficiency. This is all great...

Homework Statement Capacitors of 19.1 uF and 2.1 uF are charged as a parallel combination across a 229 V battery. The capacitors are disconnected from the battery and from each other. They are then connected positive plate to negative plate and negative plate to positive plate. Find the...

So I was wondering if I could get some help and advice on a project I am working on. I have next to no experience or knowledge of electrical circuits so I appreciate your patience. I am trying to power a structural health monitoring system "accelerometer" unit on a bridge using...

Hi. How would you calculate the total electric potential energy of a battery containing two cells (just an example), with for instance 20 V (cumulative, if cells are in series) and runs on a 60 A circuit. Is it required to have the charge of the battery to calculate total energy in joules...

Homework Statement Two batteries with emf e1 = 20.00 V and emf e2 = 19.00 V and no internal resistance are connected to two resistors with resistance R1 = 2.00 ohm and R2 = 8.00 ohm as shown in the figure. What is the power being delivered by the battery with e1?Homework Equations P=IV and...

Homework Statement Two parts: With the jumper cables attached, how much current passes through the starter motor? With the jumper cables attached, how much current passes through the dead battery? Homework Equations Ohm's Law and Kirchhoff's Laws The Attempt at a Solution...

why positive or negtive polar of battery can not attract small objects ?

Power delivered by Battery to Capacitor in "Time Constants" Homework Statement < Pic 1 > The Attempt at a Solution < Pic 2 > As you see, I'm getting answer as (ln 2)/2 but the answer is just (ln 2) Please tell me where I'm wrong.

Homework Statement A voltmeter whose resistance is 1000 ohms measures the voltage of a worn out 1.5V battery as .9V. What is the internal Resistance Homework Equations The Attempt at a Solution In order to do this, I Solved for the Equiv Resistance of the circuit (leaving in...

Homework Statement The field generated in Fig. 3 is due to a battery connected between the center conductor and the sheath. What is the voltage rating of the battery? (i.e. what is the electric potential of the positive terminal with respect to the negative terminal of the battery?) I...

what is difference between an electric cell and a battery?

Homework Statement Homework Equations P = IV The Attempt at a Solution Part 1 For the first part I solved P = IV for the current flowing through the bulb to find that I = 0.5 A. I then divided 115 Ah by 0.5 A to get 230 hours. Now, I don't really understand what I did...

Recently, there is a new type of battery is developing that has silicon anode which is able to absorb 8 times more Li-ions than graphite anode. http://en.wikipedia.org/wiki/Nanowire_battery" But if I no make mistake the main limitation of Li-ion battery is its cathode, not anode. Usual...

So I have this small multimeter - DT-182. There are some settings for checking batteries. On the 1.5V battery setting in little parentheses below there is written 40mA. So a fairly full battery displays around 35 something on the screen. What is this "something" and how exactly does this test...

Let's say you have two batteries in parallel and at the same voltage. Well batteries fluctuate in voltage and when they are drained they will have a somewhat lower voltage than what they started with when fully charged. Because of this, when power (or current rather) is being drawn from a...

Hello, I am new to this and need some help designing a project of mine. I am trying to build a small battery powered heater using nichrome wire. I am going to be heating a liquid within a coiled copper tube and plan on heating it by wrapping the tube in nichrome wire. Since this is a...

Homework Statement A constant current of 3 A for 4 hours is required to charge an automotive battery. If the terminal voltage is 10 + t/2 Volts, where t is in hours, how much energy is expended? (dw) Homework Equations i = dq/dt v= dw/dq (w = work in joules) p = iv The...

I have several Questions. 1. What are the elements commonly used in a battery and why are they used? 2. What purpose does each chemichal in abattery serve 3. How does a battery truly work? thanks for answering, all postr will be helpful, BT

Hi! I'm working on a circuit, and I'm trying to figure out a way to output a larger voltage than 3.7 from a lithium battery, and to be able to adjust that voltage when needed. e.g., output 10 V for 2 seconds, then 9 V for 2 seconds. I looked into a charge pump setup (create a voltage across...

Homework Statement The bit I'm struggling with is to determine the time constant \tau for the referenced circuit after the switch is closed. Constants are given in the image, which can be found at https://www.physicsforums.com/attachment.php?attachmentid=12737&d=1203627574. Homework...

I have a laptop, and at first it used to go up to 2.5 hours without plugging. Now it stays up to 10 minutes. A friend of mine has a totally disabled battery. Another friend has a battery that used to stay up to 5 hours without plugging and now is in a similar state as mine. And the list goes...

Yesterday, I purchased a new laptop, more specifically a Dell Inspiron 15 E114. Due to my excitement, after I unpacked it, I inmediately plugged in the cord to check out the software, and I explored its features for about 20 minutes, then I turned it off and unplugged it. After that, I...

Which method is more advantageous - economically as well as scientifically? Charging a battery (rechargeable) just after its use or charging it fully after its complete discharge? I read in my book that in the case of lead storage batteries, the PbSO4 produced during discharge can be easily...

Hello all First time post here. For a Christmas Village display for the houses, I bought a 15 bulb LED light set that is battery powered that I planned to convert to Transformer power so one, it can be controlled by the house voltage timer system I am using for the other lights, and two, so I...

Homework Statement A 12.6 V battery supplies a 2.0 A current for 10 minutes. What is the work done by the battery during this process? Homework Equations I=q/t The Attempt at a Solution I'm really drawing a blank on how this connects to work.

http://arstechnica.com/science/news/2007/09/supercapacitor-battery-could-lead-to-instant-charging-long-charge-life.ars Ive been reading a little on this EEStor thing. With so many negative comments about it and secrecy behind it, I began pondering it and would like more feed back...

I have 2 rechargeable 18v battery pack from cordless drill which I'm thinking of using as laptop charger and compact camera battery charger. These packs comes with 220v adaptor. Me and my 12yo son will be doing a week-long research for his school project (climate change) this Xmas break...

Thermodynamics: Gibbs free energy from this "battery" reaction? Homework Statement I'm reading my textbook and it gives an example. The dH of the reaction is -316kJ/mol so that much energy is released by the reaction itself. Additionally, the entropy of the products are higher than the...

1.A parallel-plate capacitor is fully charged and then disconnected from the battery. The plates are then moved closer together, how does the charge on the plate change it needs to be stated whether the charge on each plate increases, decreses or stays the same Homework Equations...

Ok guys I need help! Its been a while since I last opened a physics workbook and now I'm back to studying to try and further my career and I've come across an internal resistance question that I can't get my head around! A resistance of 10.5 ohms is connected across the terminals of a battery...

Hey team i need some simple electrical engineering advice. I am a surgery resident and I need battery powered LED that flashes at 8 times a minute. Research funding is about as easy to find as health insurance so I am trying it on my own. I thought about just taking apart a flashing light that I...

what will be the difference if the solar panel will be directly connected to the 12 volt battery or the solar panel is connected to a switching regulator before connected to the battery..which is faster to charge?..and what will be the difference in terms of power transfer?

Homework Statement A 48 V DC wind turbine is hooked up to charge a battery bank consisting of four 12 V batteries in series. The wind is not blowing, but the batteries must supply 2 loads. One is a light bulb, rated at 175 W at 48 V; the other is a heater, rated 1000 W at 48 V. The loads are...

Homework Statement I need to calculate the total current a battery supplies in a steady state. The voltage supplied by the battery is 2.0V, and the total effective resistance of the circuit is 22kΩ Homework Equations i=V/R The Attempt at a Solution i=2/22000=9.09*10-5amps Is...

Homework Statement If the cell capacity of a cell is 3,5A.h; calculate the number of electrons that flow through the cell in 30 minutes. Homework Equations Q= I.t The Attempt at a Solution Q= I.t = 3.5x(1800) = 6300C 6300/(1.6 x 10^-19) = 3.94 x 10^22 electrons

hello friends, Suppose my car battery current voltage is 10V and the alternator is charging my battery during the car run so if the voltage arriving at battery terminal is 13V then what value of voltage i should consider in my equivalent circuit of battery? my equivalent circuit consists of a...

I am currently designing an aluminum-air battery(e.g. http://en.wikipedia.org/wiki/Aluminium_battery) for a lab class that I'm taking. It seems like the prototypical design for one of these batteries is to have an aluminum foil anode beneath a paper towel soaked in salt water as an electrolyte...

Hi, I'm trying to work on this interesting little project that involves charging a 6V battery using a simple DC generator powered by a wheel spun manually. The equations for the DC generator output would be : E = N B v sin(theta) x 10-8 if I'm correct. E being the voltage, N=number of...

What would happen to an electroscope if a wire from the negative or positive terminal of a battery is touched to an electroscope? Will the electroscope deflect or will it do nothing?

A battery lies on a table. Does it produce an electric field in its vicinity when no conductor connects its terminals together? If yes, do you have an idea of its magnitude? Thanks.

1. A battery drives an electric motor which raises a 20 kg mass at a steady speed of 3m/s vertically upwards. If 90% of the electrical energy supplied is converted to mechanical energy and the current flowing is 5 A, find the emf of the battery. 2. W=QV p=mv P=IV K.E=.5mv^2 3...

I am on the Earth's surface and I want to lift my 1000kg rock up 1m. I quickly calculate the amount of work required to accomplish this feat: 1000kg * 9.81 m/s2 * 1m = 9800 kg m2/s2 or 9800 joules thats really not that much work. i see from...

In Ideal Short circuit i.e the resistance of the medium is zero,there is no power delivered by the source(batterey which involve chemical reactions and have no internal resistance i.e ideal).Then is the source Get down or not.If yes then why?

A capacitor in a RC circuit is initially uncharged. What is the charge on the capacitor being charged up by a 25 V battery for a period of two time constants of the RC circuit? (C = 15 µF, R = unknown) How do I find Q?

Dear Experts, My phone battery indicator shows 50% charged. My question is, assuming the phone needs 5v to operate, what does the 50% mean? Is it : 1. 50% current / power is left? If so, 50 % of how much amperes / watts? 2. 50% of 5v is left? Unlikely since that would mean too...