# Questions tagged [batteries]

Devices to store chemical energy and convert it to electrical energy.

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74 views

### Resistors parallel to short circuit

I have a trouble solving this problem. (Actually, each resistor is not parallel with the bottom wire since the voltage across each of them is different with that of wire.) In the manual, the bottom ...
178 views

### Estimating the battery capacity using current power consumption and battery percentage

I want to estimate the current maximum capacity (in kWh) having the current power consumption (in kWh) and the state of charge of the battery (in %) available in a time series. I do not have a full ...
297 views

### What are the physical limitations on energy density for a useful, safe battery, and are we anywhere near them?

Energy storage seems to be a fairly major bottle neck in technological development at the moment, especially for important things like clean-energy powered transport, but also for consumer goods. Are ...
124 views

### Does current flow when you connect a battery to earth?

Let's say that the earth has 0V and everything is ideal, does current still flow and why?
38 views

### Potentiometer's working

I know that in a closed circuit with multiple batteries, current is provided by the battery which has the maximum voltage. Let's suppose that $E \gt V$. Now, the voltage $V_b$ at point $b$ will ...
92 views

### RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam; A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
22 views

### Question about electrochemical reaction in fuel cell

The electrochemical reaction on the anode side of a fuel cell can be expressed as hydrogen split into hydrogen protons and electrons. I'm doing some research about the electrochemical reaction in a ...
84 views

### How could a bulb light up if aĺl the voltage is lost in the resistor?

I recently came up with this slight confusion about voltage loss in resistors/resistance. So for example My circuit has a 12V battery, a 2 Ohms resistor and a Bulb. If we use the V=I.R formula then a ...
94 views

### Parallel voltage source concept

I am having doubt understanding this: If two voltage sources V1 and V2 are connected in parallel with different voltages like 2v and 3v is it possible or the scenario is wrong. An example is this ...
29 views

### Does dropping a battery on the floor partially discharge it?

Can one mechanically discharge a battery? And if so, what is the mechanism responsible for that?
163 views

### Quartz piezoelectric battery

I'm designing a battery that uses quartz crystals to hold/produce a current for a long time using piezoelectricity. My question is: Would it be more efficient to have multiple small quartz crystals ...
54 views

### Is this Thevinin equivalent of a voltage divider, correct?

Found the PDF version of The Art of Electronics (Horowitz and Hill) recently, and, having nothing better to do... I thought I'd give it a read. It wasn't long before I hit a wall (courtesy: my inept ...
40 views

### How is the loop law applicable when I connect a battery with an ideal copper wire?

We would have a potential rise but where is potential drop? Considering wire to be having negligible resistance.
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I am looking for answers regarding a paper I am reading right now. I either found stupidly high values or strange SI unit. This paper is about battery charging, and the battery model used brings me ...
585 views

### Current from Middle Battery in a Two-looped Circuit

With this question, as with many tutorials of similar questions I’ve found online, my textbook only mentions three currents: $I_1$, which flows through the left loop from and to the 19 V battery, $I_2$...
102 views

It is my understanding that internal resistance of the battery is mainly due to resistance of its electrodes and electrolytes. During the charge or discharge of the battery, there's a potential drop $\... 0answers 432 views ### How does a battery work? How does the positive terminal of the battery attract electrons? Does the electric field emitted by the positive terminal attract the electrons? 2answers 267 views ### How to vary the current using batteries? I am making a door bell as a school assignment. It works by having a solenoid produce a magnetic field which attracts a pice of iron attached on a conductor. when the iron is attracted towards the ... 0answers 16 views ### Field forces in a battery Does a battery take time to reach its maximum voltage because it will take time for the field forces to build up since the electrodes are initially uncharged? 0answers 36 views ### Is this explanation of Voltage Drop correct? As a general outline of what happens when the battery is turned on, here is what happens: When the battery is turned on, a wave propagates within the circuit to determine the current of the sytem.At ... 1answer 32 views ### How cell drives electrons to flow in a metal wire? This was my approach using some facts I'd known- At cathode and anode of a cell reactions take place making positive terminal positively charged and negative terminal negatively charged I.e. there are ... 0answers 29 views ### Concentric cylinder cell constant For a concentric cylinder cell (with liquid dielectric), mathematically the equation for the cell constant will always yield a lower value than for the parallel plate case for the same volume of fluid.... 1answer 36 views ### Powering an electromagnet for a long duration Looking to power an electromagnet requiring 12 DC volts at 4 Watts, and wondering what size battery I would require to do this for 4 weeks? My maths so far is, and I am not sure this is correct: <... 1answer 30 views ### When the external resistor increases in temperature, why is the calculated value for internal resistance higher? Say we had a circuit with a cell (with internal resistance)and an external resistor of 10 ohms as shown: The 10 ohm resistor then increases in temperature, leading to an increase in resistance in ... 4answers 50 views ### Finding the charge on a capacitor (RC circuit) I am having trouble finding the charge on the capacitor for$t\rightarrow \infty$after the switch has been closed at$t=0$. I already know the current$I$. I also have to find out on which sides the ... 0answers 36 views ### Calculating energy capacity of a battery I understand that you can easily calculate the energy capacity of a battery simply by multiplying the mAh rating by the Voltage. However, my question is how do the manufacturers calculate the mAh ... 0answers 33 views ### How to choose the method of circuit analysis? I was just doing some revision, and I was wondering how to figure out which method to use for solving a given circuit? I tried using mesh analysis on the attached circuit but I got it completely wrong.... 0answers 26 views ### Question about amp-hour and batteries in series I am a little confused about this wiring batteries in series and parallel and the effect of this on total time that these batteries can last(I suppose this is called amp-hour, correct me if I'm wrong) ... 2answers 39 views ### Empty and fresh battery in series If you have 2 (e.g. 1.5V) batteries in series and one is dead/empty, what is the reason why a device is not working? Lack of voltage (1.5 + 0 is simply not enough for the device to operate)? From my ... 0answers 26 views ### Electronegative - Electropositive atoms can attract ions? Well I was just wondering how a copper-zinc battery works, with electrolyte an equilibrium of water and NaOH. It says that NaOH is dissolved (I understand that) into water forming H$_4$O$_8$Na+ ions ... 0answers 42 views ### What force is responsible for the movement of electrons in a current caused by an electrochemical source? From what I have read, batteries provide an electrochemical potential that causes electrons to move from the negative terminal through a conductor to the positive terminal. I have read numerous ... 1answer 23 views ### In a Radioisotope betavoltaic cell, does the amperage or voltage decay? In a tritium-powered betavoltaic cell, the power output obviously decreases as the tritium decays. Is it the voltage, amperage, or both that would decay? 1answer 82 views ### Potential divider formula Hi, does applying resistance to a potential divider affect the output voltage? For example, if I were to put resistor R midway across a variable resistor would output voltage still = (R1/R1 + R2) x E? ... 3answers 44 views ### Does current get divided between single cells or only through parallel connections? So let's say I have 2.5KW motor that runs at 48V, drawing peak around 55A. Let's also say that I have an 18650 battery bank, which consists of 13 batteries in series, to give me 48V, and 4 parallel ... 1answer 43 views ### Voltage is changing. Then why do we use a constant value (if given as battery is 3V)in doing sums.? Actually the potential difference changes throughout each part in a circuit and the electrons dont have the same energy (say the battery is 3V) throughout the circuit.then why ,when do we use V=3V as ... 3answers 58 views ### Work done on a battery Consider a battery of EMF$E $and label its positive terminal$P $and Negative terminal$N $. Consider current flowing through the battery from$N $to$P $. Then work is done by the battery. This ... 2answers 33 views ### New charge of a capacitor How does the load of a charged capacitor vary when placing a dielectric between the plates while keeping the capacitor connected to the battery? If we have a capacitor that we have charged to the ... 1answer 31 views ### Seperating Charges in a Cell Sorry for not being detailed for my question here but how do charges seperate in a cell and when the electrons are pumped out of the battery does it return and become positive ? Yet again sorry if I ... 2answers 74 views ### How Can the Same Resistance Cause Different Voltage Drops? Lets say we make two circuits, one a simple circuit connected to a 9 V battery with say a 9$\Omega$resistor attached,and one another simple circuit connected to a 9 V battery with a 9$\Omega$... 1answer 256 views ### Charge distribution in series combination of capacitors its a normal series combination of capacitors,only the inner plates are placed differently,one in the beginning and one in the middle,will it not alter the charge distribution ? that is if we will ... 1answer 298 views ### Forces on charges moving through battery In the attachment, which comes from a text "Introduction to Electrodynamics" by Griffiths. There are two statements: "Within an ideal source of emf (resistenceless battery), the net force on the ... 1answer 71 views ### Conceptual scheme of circuits What would happen if I were to connect two ends of a battery with a magic wire of no resistance? In the conceptual scheme of modeling circuit behavior there is always a circuit with a resistor given ... 1answer 59 views ### Charging two wet cell batteries in parallel from an alternator If I charge two wet cell batteries in parallel from an alternator and the smaller starter battery only needs a short charge to reach full state of charge and the service battery requires a long ... 0answers 124 views ### What is the theoretical reasoning behind calculating emfs in series or parallel? First off, I did some research on my own but the answers weren't satisfactory. The analogy of the water pump makes zero sense as I see no way how "Potential" is even comparable with "Dynamic Pressure".... 2answers 153 views ### Stacking batteries and electron flow About Fuel Cells and Batteries: I understand the analogue with increased water height as two cells (battery or fuel) are connected in series. However if we for instance have two batteries contected in ... 1answer 74 views ### What is the equivalent of the “amount of fuel” for a battery? I am trying to make a performance diagram of an electrical powered device vs range, speed, etc. I want to compare it using the equivalent of fuel for a battery? I am not sure if it is just voltage... ... 2answers 191 views ### Trying to understand the electric potential and potential energy I am trying to understand some facts on electrical potential and potential energy. It is quite confusing in the text to say that the zero potential could be freely chosen for convenience. In that case,... 0answers 876 views ### Why are magnets attracted to negative side in battery I have been experimenting with magnets, and built an Homopolar motor however it works but the magnet only attracts the negative side of the AA battery (the flat side of a battery) which I thought was ... 2answers 81 views ###$V = 4 volts$but$I = 0\$

Recently in my school, I tried to generate electricity from plants in a flower pot with copper and Zinc electrodes. The Potential difference in the voltmeter read 2 to 3 volts but when I connected the ...
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### Amount of energy that can be stored from Faraday flashlight / linear alternator?

You'll have to forgive me if this question is either extremely elementary or does not make sense — I am a civil engineer with little E/M physics background beyond high school education. I am working ...