Questions tagged [batteries]

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

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1answer
42 views

When we charge a capacitor via a battery then why does exactly $1/2$ of the work done by the battery get converted to heat? [duplicate]

I know the $\frac{QV}{2}$ & $QV$ stuff but I want the logic. You would say it's due to the resistance that the work gets converted to heat. But, why is it that exactly half the value of work done ...
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1answer
28 views

What happens when the length of the uniform wire is more than or less than 54 cm?

I understand how to solve this (when $V_{BC}$ is equal to the emf of the second cell then the current through the second cell is zero). However, I'm curious what happens when the length BC is more ...
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1answer
19 views

If no current is able to flow through a capacitor what will be the node voltage on the other end of the capacitor opposite the voltage source?

I'm working on a simple circuit problem including a capacitor and I am calculating the node voltage Va. By using KVL, I find that Va is 5V. But how does the 5 volts appear on at Va if it is not ...
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2answers
43 views

Voltage and potential energy in a circuit

I'm wondering about the meaning of voltage in a circuit. Voltage is always described as related to the potential energy of the charge carriers. Often, the analogy is made to gravitational potential ...
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1answer
24 views

How can a coil self-induce voltage at $t=0$?

Assume you have a resistor and an inductance in series. When a DC supply is connected at t=0, the coil is inducing an opposing voltage, which is the same as the DC supply's voltage. The current ...
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2answers
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What happens when a battery discharges?

Questions I am interested in: What determines the amount of current a battery can supply? What changes when a battery discharges - voltage, max current, or both? What is the best predictor of the ...
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1answer
54 views

If the current of the branches in a parallel circuit always add up to the same total, why isn't this true in this example?

Here is a picture: I did some math and got this table: Why doesn't the current add up to the total, since it's supposed to in a parallel circuit? I used Ohm's law to calculate everything. My ...
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7answers
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Understanding the zero current in a simple circuit

I've simulated the very simple circuit shown below: As you can see, it has two batteries of 1.5 V, and three identical resistors. The electric currents passing through each wire are also indicated. I'...
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2answers
88 views

Should I simplify the circuit or use the Kirchoff's method? [closed]

The main goal here is to solve for the values of $I_1$, $I_2$, and $I_3$. Should I use simplification in this circuit or should I divide this circuit into two junctions and apply Kirchoff's method? ...
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2answers
79 views

What happens to electrons in a cut wire?

what happens to electrons in a cut wire. I know it is dangerous but out of curiosity if there was a power cable cut and connected to the outlet, the electrons would be dispersed in the air when they ...
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2answers
59 views

Conceptual understanding of how a battery ensures that a capacitor has the same potential difference as it?

I was wondering how exactly a battery is able to ensure that a capacitor connected to it would have the same potential difference as it. Like, thinking about a battery similarly to a capacitor, I ...
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2answers
24 views

What is an isolated system in capacitive circuit?

Does isolated system here means that the plates of capacitor need not be connected to terminals of a battery?
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1answer
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How does electric energy travel at speed of light when electron drift speed is so slow it cannot dissipate the voltage difference in that time?

Edit: Please let me clarify I read answers on this topic and I know the analogy of sound wherein although the air molecules from source don't reach you as sound, the wave pushes on neighboring ...
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1answer
37 views

Would increasing separation of terminals of a battery increase potential differnce?

If my understanding is correct, the chemical reaction in a battery is basically a conveyor belt that moves electrons from the positive to the negative terminal of the battery until the electric field ...
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3answers
53 views

Charging of a capacitor by battery

I know that a battery does work when it takes positive charge from one plate of capacitor and deposits it to the other plate, thereby creating equal and oppositely charged plates having electric field ...
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Why does the salt bridge in the galvanic/voltaic cell maintain the potential difference instead of neutralising it?

The potential difference between the copper and zinc plate pulls the electrons in the wire but not the ions in the salt bridge. Why this discrepancy ?? Suppose ...
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0answers
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Battery/cell circuit symbols

I'm teaching some younger kids physics, and we are looking at circuits. When recapping circuit symbols, I remembered that there were different ones for a cell and a battery. A battery symbol looks ...
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2answers
61 views

How does the electrochemical potential within a battery work at the level of basic E&M?

The explanations that I've seen for how batteries work (like this one) tend to go along these lines: One electrode "has an electrochemical potential that makes it want to give up electrons" ...
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32 views

Confused about inductors and how they “react to changes in current” [duplicate]

When you have an RL circuit and you close the switch allowing current to flow, I always thought that the inductor opposes that sudden increase in current as if it was just a circuit without an ...
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Can anyone help me to solve this circuit? [closed]

Assuming the diode voltage is 0.7V, how to calculate the current flowing through the diode? And how does the earthing function in this circuit?
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2answers
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Is this circuit going to work and how to build it? [closed]

For a school project we have to build a circuit with a capacitor and measure the current. Am I even going to be able to measure a current if I place the switch like in the picture? I thought there ...
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1answer
32 views

Are the potentials of the electrolytes equal in Galvanic cell?

My book defines Electrode Potential for a Galvanic Cell as follows: A potential difference that develops between the electrode and the electrolyte is called Electrode Potential $$E= V_{electrode} - ...
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3answers
87 views

Behavior of this RC circuit

note: This may be a homework question but I am not asking anyone to give me the answers as I already have them: Im only looking for an explanation for what's actually going on. Question: once the ...
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2answers
51 views

Capacitor with intially having charge $q$ on both plates and then battery connected

What would happen to capacitance and other quantities like Voltage if I initially take a Parallel Plate capacitor with each plate having equal charge "$q$" and then connect it to a constant ...
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2answers
60 views

Why current drops when voltage increases?

https://www.youtube.com/watch?v=ubZuSZYVBng&t=329s In the video above the man put a 200 thousands volt ball near a non-charged one and a very tiny current appear between them. But I think with ...
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1answer
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Will a battery discharge if one pole is connected to the ground?

With static electricity it's clear that free electrons would go to the ground. But I have significant doubts that an accumulator battery will discharge if one of it's electrodes is connected to the ...
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1answer
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Question on electricity and the basics of potential difference

I am having some difficulty understanding how batteries work. I don't quite understand what exactly potential difference is. My textbook says it is the work done per unit charge to move an electron, ...
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1answer
29 views

Why is electric current during charging battery equal to vb1-vb2/r1+r2 and any resistance in circuit

Why when we connect two batteries in series but in opposite directions current equals vb1-vb2/r1+r2. I can't understand why we subtract the current of the smaller battery from the greater battery. I ...
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1answer
55 views

Why does a Secondary Cell have a lower internal resistance than a Primary one?

Hi I was wondering why would a secondary cell have a lower internal resistance than a primary cell. I had read somewhere it was due to the fact secondary cells used lead acid which has a lower ...
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1answer
54 views

Why does the ammeter reading change in this way? [closed]

Question: Without calculation, state what happens, if anything, to the reading of ammeter $A1$ if: The $2 \ \Omega$ resistor $R1$ is shorted out with a thick piece of wire The piece of wire is ...
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2answers
106 views

Is the energy supplied to a capacitor by a battery the same as the energy stored by a capacitor?

If we have three capacitors in series, would the energy supplied to the system be the same as the energy that is contained in the equivalent capacitance of these three capacitors?
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42 views

Kirchoff's Loop Rule

For $V_2$ , why is there no current flowing from the positive terminal from $V_2$? In other words, why does $I_3$ win out from the current that would be flowing from $V_2$ if it was the only battery ...
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3answers
620 views

Does current pass through an ideal battery?

According to my physics book, inside a resistanceless battery (it is a part of a closed circuit) the conservative field has the same magnitude but opposite direction to the non conservative field. ...
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1answer
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Why is the cathode filament in an x-ray tube negatively charged?

Quoted from BU-104b: Battery Building Blocks: The electrode of a battery that releases electrons during discharge is called anode; the electrode that absorbs the electrons is the cathode. Based on ...
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2answers
101 views

How does the newly unveiled Tesla battery have 5x the Energy Capacity and 6x the Power, but only 16% increased Range? [closed]

I just saw some exciting news from Tesla regarding a new battery, but I'm quite confused. As you can see on the headline of this article and the accompanying Tesla infographic: The claim is that the ...
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2answers
59 views

Why can't an insulator let electricity pass?

I have read about this: Essentially in an insulators there is a big energy gap between the (valence) and the conduction band which is why there aren't many free electrons in a insulator. How does ...
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4answers
756 views

In a circuit, does a battery create electrons which it 'injects' into the copper wire? [duplicate]

Are electrons created from a battery and then 'injected' into the copper wire? If no, does that mean the battery loses power because the copper wire has run out of free electrons?
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3answers
67 views

Why don't electrons still have energy after completing a circuit with a battery?

Firstly a battery causes an accumulation of electrons in the negative terminal right? Hence the positive terminal is relatively positive and so an electric field is produced. This electric field will ...
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2answers
54 views

Why does a real DC circuit with 1 resistor have uniform current?

Imagine a DC circuit with small but non-zero resistance in wires and large resistance in a single resistor in series with the battery, all ohmic. Connecting the battery I imagine a surge of electrons ...
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2answers
78 views

Can a battery lose electrons?

I asked my teacher what would happen if I have a 1Ah battery and I expel (out of the circuit, for example with an electron gun) the electrons with a current of 1A for one hour, in such a way that the ...
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1answer
42 views

Why in potentiometer we says that potential gets decreased?

here potential is said to decrease from a to b ,why it is so and why there is potential drop from a to b please explain?
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45 views

Does the negative terminal of a battery have a higher concentration of electrons?

I'm 15 and recently started electronics and I just had a question about batteries. According to a video I watched by "The Engineering Mindset", a battery creates potential difference by ...
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1answer
71 views

How this toy shown on YouTube works and can the coil be replaced by a hollow magnetic thorus? [closed]

I saw this video on YT and what I can not figure out is why the coil used in the arrangement could not be replaced by a hollow magnetic torus?
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3answers
145 views

Confusion in definition of emf

The emf of a cell is defined as the work done per unit positive charge in taking it around the complete circuit of the cell (i.e. in the wire outside the cell and the electrolyte within the cell). But ...
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0answers
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How does a battery create potential difference? [duplicate]

I'm in year 10 (9th Grade for the Americans) and I just had a question about physics. How does a battery create potential difference? It it because the electrons are gaining energy as they get pulled ...
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3answers
107 views

How does more voltage (greater potential difference) mean more current?

I know that voltage is the difference in electric potential energy between 2 points and that a higher voltage means more energy for a coloumb of charge (ie a 9V battery means 9 joules per coloumb). ...
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0answers
38 views

Is my understanding of the process of charging a capacitor correct?

Suppose, I have a parallel plate capacitor with copper plates $A$ & $B$ connected to a battery. Plate A is connected to the negative terminal of the battery and plate B is connected to the ...
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1answer
29 views

Can a voltmeter itself disturb the electrochemical potential of battery?

I'm trying to understand the effect on a system when a voltage of a system is measured by connecting a voltmeter. For example let's say we are trying to measure the voltage of a Li-ion battery. The ...
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1answer
42 views

Electric Battery

Some say that the battery supplies charge, some say that it only maintains potential difference, I've also heard that it maintains an electric field in the wire. I'm confused. What does battery ...

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