Questions tagged [batteries]

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

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Backwards proof for balanced Wheatstone bridge

We know that in this Wheatstone bridge if, $\bf{I_3 = 0}$, it can be derived that $\bf{\frac{R_1}{R_5}=\frac{R_2}{R_4}}$ . But could we prove it backwards, mathematicaly, that - if in such a circuit $...
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1answer
1k views

EMF of an ideal cell

I know it's a very stupid question but I am confused a little bit right now. An ideal cell has constant EMF of 7V. When connected in a circuit, the voltage across the cell decreases to 5V. Can i say ...
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1answer
290 views

Battery life with hot and cold wires

If a AA battery was kept at a constant temperature and was connected in a simple circuit will the battery drain faster if the wires are kept at a cold temperature or at a hot temperature? I ...
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4k views

Does current run forever in water? (assuming the supply voltage is there forever)

Suppose pH of water is $6$, I think this means there is one $\text{H}^{+}$ ion for every $10^6$ water molecules. When we plug in the battery, I believe we see a current as the $\text{H}^{+}$ ions ...
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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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1answer
1k views

Electromotive force of a battery

The definitions of electromotive force of a cell that i have read include: 1.When no current is drawn from a cell,i.e., when the cell is in open circuit, then potential difference between the ...
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3answers
1k views

Capacitors in parallel final potential difference

I was provided with the following problem. So I first calculated the total capacitance for (i), which was $$4.5 + 1.5 = 6.0 \mu F$$ Now part (ii) is the question i'm struggling at. I know that ...
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2answers
125 views

Why do batteries in series add up in voltage? (real explanation requested)

This has been asked before but I need to be clear on what kind of answer I'm looking for. All the other posts are just water analogies. I get it, you add the voltages together. And there's a magical ...
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1answer
196 views

Not understanding inductor behaviour in RL circuit

This figure from Halliday's book is perfect to go with my question. I've been trying to understand how exactly indutance works almost the entire morning, I think I need another perspective, please. ...
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2answers
246 views

Resistance in internal battery, voltage source

I was reading the post Which dissipates more power, a small or big resistor? and DanielSank's reply said Now, any circuit you would reasonably call a "voltage source" must have a low internal ...
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2answers
431 views

Diode IV experiment

Ive been looking at experiments to look at the IV relationship for a LED, but I see most of them use a rheostat instead of a series variable resistor and my question is, what is the advantage of using ...
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0answers
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Issues reading a paper about batteries

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 ...
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4answers
4k views

How can there be a voltage when there is no current?

I'm told at school that the Electromotive Force (e.m.f) of a battery equals the potential difference between the terminals of the battery when there is no current. How is that possible? How can there ...
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1answer
697 views

Can a mobile phone emit gamma rays? [closed]

I heard that inside the battery of mobile phones (but also of other electronic devices) can happen quantum leaps that cause the emission of gamma rays photons. Is this phenomenon really possible?
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1answer
82 views

Circuits in parallel of different voltages

I've been having difficulty in understanding why the voltage across the resistor $3$ is $10V$. My main problem is understanding why the $12V$ resistor couldnt for example drop $1V$ on the first ...
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2answers
912 views

Adding two same DC voltage source in parallel

In a parallel circuit(imagine two branches),with one DC voltage in a branch and another DC voltage in a branch, what is the method of computing the total DC voltage? The voltage through each component ...
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1answer
4k views

What maintains constant voltage in a battery?

I know there's lots of questions that address similar situations, (Batteries connected in Parallel, Batteries and fields?, Naive Question About Batteries, and the oft-viewed I don't understand ...
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35k views

Calculating the energy supplied by a battery

If you wanted to calculate the energy supplied by a battery in time $t$ you would use $E=VIt$ where $I$ is the current through the battery. If the internal resistance is $r$ we could also use $E=\frac{...
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613 views

Circuit with three capacitors and a switch [closed]

I have a homework problem where I have a battery connected to a capacitor and a switch that connects the capacitor to 2 others in series/disconnects the circuit from the battery. The question is: ...
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1answer
466 views

Why is the voltage in my battery rising?

While playing with some 9 volt batteries in a series circuit, I noticed that the voltage of the battery as measured by my voltmeter was increasing at a constant rate. After placing a bulb in my ...
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2answers
78 views

Current in circuits and conductivity

I'm really puzzled with a problem for a rather long time and I can't really seem to be able to solve it at all. It has to do with the electrons that move in a circuit. We know that a battery builds ...
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2answers
2k views

Emf of a Cell in an Open Circuit

Consider a cell having terminal voltage $V'$ and EMF, $V$ having internal resistance, $r$ and current, $I$ flows through the circuit in which an external resistance, $R$ is connected. Potential drop ...
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3answers
925 views

Voltmeter- Readings

What would the reading be on this voltmeter? Suppose The battery is $5V$. Would the reading be $5V$? If you see it from the other way, the two ends of the voltmeter are connected by ideal wires; ...
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1answer
16k views

short circuit an alkaline battery

i'm not doing anything related to physics, but i'm just curious : What really happen when i short circuit an alkaline battery ? some article in the net shown that fire/explosion can be happened when ...
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3answers
364 views

Does a higher e.m.f give a larger current?

I was told that e.m.f. is the work done on the charge carriers (i.e. electrons in wires or free ions in electrolytes). Does this mean that e.m.f is preportional to current (the rate of flow of charge)...
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228 views

If a resistance of $0$ ohms and $x$ ohms are in parallel does all current pass through the $0$ resistance? [closed]

If a resistance of $0 \Omega$ and $x$ (and $x>0$) are in parallel does all current pass through the $0$ resistance? For instance in the following circuit: Set variable resistor to o ...
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3answers
1k views

How does connecting batteries in series work?

My question may seem naive so please bear with me. I just began learning about circuits and I am having problem seeing how two or more batteries can be connected in series and how the current flows in ...
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1answer
72 views

Charge generated by battery or wires?

According to emf concept,we say that due to potential difference between electrodes of battery, electrons or charges want to move to opposite electrode. But electrodes are not joined. So they have to ...
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2answers
3k views

Increase in mass of battery of my smartphone [closed]

The charge on my smartphone was zero. I charged my phone to its maximum capacity. How much mass $\Delta m$ did my mobile gained after charging the battery? Maximum capacity of the smartphone's ...
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1answer
101 views

Current relationship with different light bulbs

I have a circuit in where there are 3 different bulbs (circular, oval, and rectangular, the circular is the dimmest, the rectangular is more brighter, and the oval is the brightest. Now , I am ...
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2answers
3k views

Working of a potentiometer

Why do we achieve a zero deflection situation in the galvanometer when we slide the jockey on the potentiometer wire ? Or what is happening in the secondary circuit that causes zero deflection in ...
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3answers
175 views

Parallel combination of batteries [closed]

What is the current through resistance of 6 ohm in the figure. please explain through Kirchoff laws and keep it simple on college level
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1answer
101 views

Does this kind of circuit work?

I am going to see if having electric voltage through fruit will slow the decay. So I have my treatment set up here: and I am going to wrap this so that: However, my teacher told me that this might ...
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1answer
131 views

No-answers-found Li-Ion battery questions [closed]

Background I've spent almost 7 hours researching about Li-ion batteries because my Galaxy S2 only lasts 2 hours with all turned off and only 40 apps installed (removed system apps and bloatware) and ...
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3answers
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Why is the potential drop zero across a wire of zero resistance? [duplicate]

Okay, even if the wire has zero resistance, then charges are being transferred in the direction of electric field, which means there must be a potential drop according to the distance travelled by the ...
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2answers
2k views

How is potential difference maintained in a battery?

I am beginning of learn electricity so sorry if my questions are confusing or does not make sense. My question is specifically about how voltage (which I guess is due to separation of uneven charges) ...
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1answer
265 views

Simple circuit with mesh current. Two resistors, two batteries [closed]

I can't find current through 6k resistor using mesh-current method. Using KVL on left and right side you get: \begin{align} V_\text{4k} + V_{6k} - 10V =& 0 \tag{left loop}\\ 13V \text{(voltage ...
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2answers
5k views

Batteries in series vs parallel

As fa as I understand it, two identicle batteries in parallel will give double the amperage than just one battery and two batteries in series will give double the voltage. If my understanding is ...
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3answers
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What is the volume of gases liberated when a battery is charged?

Apparently Hydrogen/Oxygen are liberated when a Lead-acid battery is charged. If true, how does one calculate the expected volume & rate at which each gas is liberated when a battery is charged?
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1answer
272 views

Why is the work done by a battery associated to a potential energy even if the processes are not reversible/conservative?

Consider an isolated capacitor (no battery). Since the electrostatic force is conservative, the infinitesimal work done on the capacitor plates can be written as $$\mathrm{d} W=-\mathrm{d} U_e $$ ...
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1answer
40 views

Why is Alternative energy most commonly stored in metal acid batteries? [closed]

Why is alternative energy most commonly stored in relatively expensive metal acid batteries, which have a short life, rather than hydrogen gas accumulated through electrolysis? Hydrogen is a ...
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1answer
74 views

Battery doing work on electrons [duplicate]

I learned that inside a battery, when we put a circuit, the battery takes electrons on the positive side and do force on them to place them in the negative side. This work done is converted into ...
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1answer
532 views

How does a battery work and create a field inside it? [duplicate]

There is an explanation of how a battery works that says that inside the battery (in the positive charge convention) there is a field and the battery does work on the positive charge against the field ...
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2answers
3k views

Will a battery connected to the Earth eventually deplete?

I've been thinking about this, and my answer is leaning towards yes, but I couldn't find any definitive answer by Googling. If the higher potential side of a typical battery is connected by wire to a ...
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2answers
98 views

I don't understand something about battery voltage

I'm trying to understand voltage and there is a site that says that the battery do work to a positive charge to move it from the low potential terminal (negative) to the high potential terminal (it ...
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1answer
85 views

Why do we use the term “voltage” for a battery?

Voltage or potential difference is the difference of potential energy of two points in space per unit charge in an electric field. A battery creates an excess in electrons in one side and a lack in ...
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1answer
2k views

Internal resistance in batteries in parallel

I am doing an experiment where I measure the internal resistance of two battery cells. I've measured the internal resistance of both of the cells, and when they were in series. The series internal ...
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1answer
196 views

What limits a batteries current when its terminals are connected with a low resistance conductor?

My question essentially is concerning what (if anything) prevents really high current flow (amperes) in a battery if the terminals were to be connected directly with a low resistance conductor? For ...
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1answer
57 views

Emf must be greater than it is supposed to be

Suppose a battery of negligible internal resistance which creates a potential difference V across its terminals is connected to a resistor R through wires of negligible resistance then it creates ...
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1answer
216 views

How much tritium would be needed for 1 amp using betavoltaic? [closed]

How much tritium would be needed to produce 1 amp of continuous current in a betavoltaic system?