# Questions tagged [batteries]

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

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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?
2answers
72 views

### Why is the electric potential difference independent of resistance?

According to wikipedia the definition of electric potential difference is as follows: The difference in electric potential between two points (i.e., voltage) is defined as the work needed per unit ...
1answer
55 views

### is this the reason why current doesn't flow over a resistance if there is another path without resistance? [duplicate]

Let's suppose that a single battery is connected with a wire, which does not have resistance. Electrons will start to flow , in reality, with a wire with resistance, a potential difference would be ...
2answers
605 views

### What happens when a battery is connected to conductors?

What happens to the electronic flow inside two conductors when they are connected to the terminals of a battery but not mutually? Why do they reach at the same potential as that of the terminals? ...
3answers
174 views

### What determines the voltage in a battery?

This diagram problem has got me thinking about what determines the voltage in a battery. At school, we were taught this method of giving a value of voltage to points in a circuit. However, I do not ...
2answers
39 views

### Compare the time the power sources in these circuits will last

I am trying to conceptualize the time which a battery will last in a given circuit. Below is an example from which I will explain the questions which I am struggling with : Lets begin by asking this ...
1answer
65 views

### Realistic energy output of a battery

An answer from the post "Battery life with hot and cold wires" talks about Peukert's law related to the battery capacity. Now, within the scope of undergrad electromagnetism courses, the following are ...
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? ...
5answers
267 views

### What exactly is “voltage drop” across a circuit element?

what exactly is "voltage drop" across a circuit element? I don't quite understand what this means.
1answer
174 views

### What is the difference between EMF of a battery, its potential difference and the current supplied by the battery?

Now, I know that emf is measured using an ammeter, while potential difference is measured using a voltmeter. But why is that so? What do we mean when we say the emf of the battery is say, 3V, and the ...
2answers
23 views

### As there is a potential drop across resistance, then why in parallel circuits the voltage across resistances is same as that of battery?

In textbooks it’s taught that in parallel circuits the voltage across resistances is same as that of battery but after that we also read the concept of potential drop across resistances, which creates ...
1answer
46 views

### Electrical circuits and calculating resistance [closed]

Can anyone give me some ideas about how to simplify this circuit....
3answers
93 views

### Why does the full PD across a battery manifest itself across a break in a circuit at any point?

Consider the following circuit: I want to know why the full pd of the battery can be measured across the break if a voltmeter was connected. Surely when the whole circuit was closed the charges at ...
2answers
78 views

### Charging a battery

So we have a charger outputting V volts and $I$ Amperes and two rechargable batteries of the same capacity $Q$ coulombs but different emf's $V_1\&V_2$. Which battery would charge faster? ...
1answer
30 views

### DC Battery Charging Question

I have a 7.4v LiIon that hold 1450ma. I have a variable DC bench power supply that I can crank up or down and adjust as needed. I want to quickly charge the battery and noticed if I adjust the ...
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 ...
2answers
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 ...
2answers
408 views

### How does the internal resistance of a cell vary with temperature?

Does anyone have a physics explanation to why the internal resistance of a battery decreases as the temperature increases?
6answers
12k views

### Why do we use capacitors and not batteries in defibrillator?

Why do we use capacitors in defibrillators and not batteries? I know that capacitors are used to store electrical energy but isn't the function of a battery just the same? Moreover, I know that ...
2answers
524 views

### Galvanic Cells and Electric Potential

In a battery or a galvanic cell, the electric potential of the battery is due to a difference of charges between the two cells like in a capacitor? So it is the electric field due to this separation ...
1answer
31 views

### What is the potential difference inside a metal conducting wire?

When a conducting wire is connected to a battery, potential difference is set up inside the battery. But, what is the case of a simple conducting wire which has free electrons inside it(without ...
1answer
396 views

### Electric field created by a battery

If I create an electric field using a battery between two parallel plates and leave the battery connected, will the electric field always exist for as long as the battery lasts, including normal self ...
3answers
426 views

### Charge density in wires [closed]

I have a very simple circuit, composed of a capacitor and a battery with constant $V$. The wires that connect these two components allow the capacitor to gain a voltage V ( the same V of the battery). ...
2answers
518 views

### RC circuit discharging capacitor, trouble understanding

If we apply loop rule while charging the circuit we get: $$\varepsilon -iR-\frac{q}{C}=0$$ The way I understand, we follow trough the circuit just before the battery, as we move trough the circuit ...
3answers
1k views

### Why is the emf over an inductor equal to that of the battery? [duplicate]

In a hypothetical circuit with only an inductor and a DC voltage source (no resistance), why is the voltage across the inductor the same as the source voltage? I get that the charges coming from the ...
3answers
5k views

### When potential difference is equal to the emf, isn't the current 0?

I have been told that the $emf$ is equal to the potential difference across the terminals of a cell when no current is flowing. Does that mean that the current is zero ($I=0$)?
2answers
31 views

### Conductors in electric circuits And electrostatics

I know from electrostatics that electric field inside a conductor is zero. I also know that there must be electric field inside a conductor carrying current in electric circuits. I am confused.
1answer
54 views

### Why can you assume the current remains the same after changing resistance?

In my physics textbook there is a question about a circuit: In question b) We find out the current in the circuit is 0.003A. This is before the voltmeter is added. In question c) a voltmeter is ...
1answer
56 views

### Creation of electric field inside a conductor

My book says that as soon as the two ends of a conducting wire touches the two terminals of a battery, it generates an electric field inside the conductor. Why?
3answers
626 views

### Why can't we add the emf of two batteries in a parallel circuit?

My teacher told me that two batteries' emf cannot be added in a parallel circuit but can be added in a series circuit. However I can't seem to fully grasp why and I think there may be some loopholes ...
1answer
67 views

### Why does a battery powered radio's volume go down as batteries age, even when the batteries' voltage is constant?

A set of batteries are used for a long period of time. Explain why the volume of a radio is low even though the voltage of the batteries is the same as when they were first bought.
1answer
242 views

### Factors affecting Battery Voltage

How do batteries produce a certain voltage, such as 1.5V or 9 V? From what I understand, battery EMF comes from oxidation of the anode, which releases electrons that can flow through a circuit. But ...
4answers
150 views

### Capacitors' working in a circuit

Does charge in a capacitor containing circuit stop flowing when the potential of the capacitor becomes equal to the potential of the battery??
5answers
675 views

### At an atomic level, what happens when you connect two batteries in series so that their voltages are added?

I can't for the life of me figure this out. I feel like i'm missing some crucial detail about how batteries work. Imagine two batteries connected in series, like this: ...
2answers
45 views

### Ideal Capacitor (Introductory Physics Question)

If I have a simple setup of a open circuit with a battery (constant battery) , resistor, and uncharged capacitor, and then I close the switch of circuit, and keep it closed until the capacitor is ...
2answers
123 views

### Why can't I series 5 D Cell Batteries to achieve 7.4 volts?

I appreciate this site that is allowing me to get an answer to a phenomena I am witnessing. I'm trying to series 5- D Cell Batteries. However I cannot make it completely through because the middle ...
3answers
11k views

### Why is there no current flow when I connect two opposite terminals of two separate batteries?

I don't understand this..maybe there is something wrong with my understanding of battery or electricity. I am learning about electricity more deeply this time. So please spare with me. So lets begin ...
1answer
5k views

### Factors affecting the internal resistance of an electrolytic cell

How does the internal resistance of an electrolytic cell (a source of emf) depend on I) the concentration of the electrolyte? II) the temperature of the cell?
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 ...
1answer
55 views

### What does it mean for a battery to be 1.5 Volt? [duplicate]

What does it mean by a battery is of 1.5 Volt ? Does it mean that it would take 1.5 Joules of energy to transfer -1 columb of charge from the negative end to the positive end of the battery ? What is ...
2answers
64 views

### How are electrons in a circuit doing work?

When electrons flow through a circuit, I don't understand how we can hook something up to the circuit (like a bulb or anything else) and have it receive power / do work. Most tutorials gloss over ...
1answer
826 views

### Voltage drop across battery with internal resistance

Consider a battery with internal resistance connected to an external voltage source; there is a voltage difference along the battery The voltage source is not drawn in the picture The voltage ...
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 ...
1answer
93 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 ...
1answer
34 views

### Alternator wear due to bad battery [closed]

I recently heard that a bad car battery (I assume "bad" means it drains faster than it was designed to) will wear out your alternator faster. How is this possible? Please note I am not looking for ...
1answer
46 views

### Energy stored in the battery of a circuit (single electron box)

Consider the following, a closed loop circuit with two different capacitors in series plus a battery that provides a voltage $V$ (in series with the capacitors). You may add a resistance if that helps....
1answer
39 views

### Determining potentials at points in a circuit with multiple batteries

I am asked to find the potential difference across the points $P$ and $Q$. Using Kirchoffs second law, I calculated the 'resultant' emf as being $E$. The p.d across each resistor would then be \$\frac{...
1answer
1k views

### Short circuit in superposition

I'm really confused about the concept of short circuits. I don't understand, why when you short those two voltage sources, 20 and 10 ohm resistors become parallel? What happens with 4, 12, 15 ohm ...
1answer
71 views

### A second law of thermodynamics related question

In the center an empty (with air) not thermally isolated room with concrete walls, floor, and ceiling, there is hanging on a non thermally conducting thread a device ("conditioner"). The weather is ...
3answers
41k views

### What happens when we connect a metal wire between the 2 poles of a battery?

As I remembered, at the 2 poles of a battery, positive or negative electric charges are gathered. So there'll be electric field existing inside the battery. This filed is neutralized by the chemical ...