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Questions tagged [batteries]

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

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90 views

Electrons and wires [duplicate]

The electrons that carry the electric energy are in wires or in the battery ? battery provides a potential difference but from where electrons flow to make for example a bulb light. If they flow from ...
62 views

Misconception about flow of charges

Let's say I have a 5V battery connected in the manner shown in the diagram. I've tried this setup with all sorts of things like pouring brine(salt water) into the soil to decrease its resistance so ...
12k views

Can single DC 1.5V battery generate 1500 watts of power?

Suppose there is a DC $1.5\mathrm{V}$ battery connected with $1.5\times10^{-3}\mathrm{\Omega}$ resistor. Then the amount of circuit current is $I=V/R=10^3\mathrm{A}$. (according to Ohm's law) I know ...
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 ...
255 views

Question about circuit with two cells [closed]

Edited - could someone explain how you treat a circuit with two cells in respect to circuit laws and also whether the section in the middle is in parallel or in series. Second Edit: I’ve researched ...
66 views

From where electrons flow to make a bulb light?

Suppose we have the "basic" stuff like a battery 2 piece of wire and a bulb. Battery has a potential difference. But from where electrons flow to make the bulb light? from wire or from battery or from ...
171 views

How is energy conserved in a theoretical circuit where you put a lightbulb and two rechargeable batteries like… (diagram included)

In the beginning the first battery is fully charged, and the second is fully discharged. As the circuit is connected the discharging battery recharges a dead second battery and light is emitted from ...
53 views

What possible advantage could there be in connecting several identical batteries in parallel? [duplicate]

In two-cell flash light,the batteries are usually connected in series. Why not connect them in parallel?
45 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 ...
1k views

Physics of batteries (volts vs charge)

Car batteries are usually 12 V. What is the difference between buying a car battery and hooking up a bunch of cheap household batteries in series? Both would register at 12 V. I assume that cars need ...
28 views

Hydrogen oxygen fuel cells

In hydrogen - oxygen fuel cell, the electrode used is carbon electrode.Hydrogen is passed through through the anode compartment where it is oxidised. Oxygen is passed through the cathode compartment ...
43 views

How a battery maintains the current in the circuit? [duplicate]

How a battery maintains the current in the citcuit? Iwant to know each and every step of this process mathematically and theoretically also.
35 views

Confusion about calculating resistances & terminal voltage

I'm looking at an exercise where a battery is powering two parallel light bulbs. Given are the battery's EMF ($12.0 V$) and its terminal voltage in this particular circuit ($11.8 V$), as well as the ...
67 views

Using a significantly large metallic sphere, could we draw out the electrons from the negative terminal of a battery?

I've pored over many articles on electrochemical cells, and I understand that on the oxidation side of a zinc-copper Daniell cell, the anode is highly negatively charged because zinc participates in ...
33 views

How are batteries affected on planes? [closed]

I'm currently an engineer and was fascinated at how technology came to be and how we were able to find out that we can take energy and essentially store it for a later time. I was thinking about ...
76 views

How can a battery 'come back to life'?

Earlier today, one of my family drained our car's battery by accident, by leaving the lights on too long. It wouldn't start at all, so they had to walk back home from where the car was parked (a few ...
3k views

What exactly is terminal potential difference?

I'm a bit confused on what terminal potential difference actually is. When doing calculations on circuit based questions I get stuck.
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?
87 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 ...
56 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 ...
664 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? ...
238 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 ...
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 ...
66 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 ...
105 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? ...
395 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.
225 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 ...
25 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 ...
46 views

Electrical circuits and calculating resistance [closed]

Can anyone give me some ideas about how to simplify this circuit....
111 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 ...
80 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? ...
33 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 ...
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 ...
87 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 ...
483 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?
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 ...
531 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 ...
36 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 ...
398 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 ...
450 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). ...
523 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 ...
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 ...
6k 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 ($I=0$)?
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.
58 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 ...
758 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 ...
70 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.
276 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 ...