Questions tagged [batteries]

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

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38 views

How electrolytes conducts electricity?

While studying electrochemistry, I came across two key points that I'm unable to understand. why does DC alone break down the electrolytic liquid and b) Why doesn't AC do the same?
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Force on a test charge inside a cell

Considering test charge inside a cell. Let the cell be in an open circuit. I know that a potential difference will develop between the two electrodes of the cell. If I take a test charge and place it ...
1 vote
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How do batteries in parallel work? [closed]

So I understand that the voltage is the amount of work done per column of charge, so its sort of a "pushing force" and amp are just the charges per second, or "amount of stuff per ...
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THÉVENIN Equivalent of Circuit [closed]

I tried to convert the right generator of, current and resistance, to a generator of voltage in series with the resistances then adding the two resistances (both in series), then simplifying, but I ...
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How do I find value of $I$ using Node Voltage analysis method? [closed]

How do I find value of current $I$, using Node Voltage analysis method ?
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How to derive Thevenin Voltage formula using Kirchoff laws?

Here's a simple voltage divider. I'm learning Thevenin Circuits now and we use the formula for Thevenin Voltage a lot (very useful!) but I'm not sure how the formula arises. My professor said I can ...
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1 answer
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What effects do inductors have on circuits?

The above diagram is a simple circuit containing an inductor. According to the right hand grip rule, it can be deduced that the magnetic field is to the right. But the magnetic field produced by the ...
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1 answer
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Why short circuit doesn't takes places in a homopolar motor?

In a homopolar motor we directly connect copper wire to a battery without any resistance with a magnet in bottom, so why doesn't a short circuit takes place?
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1 answer
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If resistance in an electric current is 0 (ideally) then would there even be current flow?

From my understanding batteries are used to charge electrons with electric potential which they then use to do work on resistors in a circuit. After doing work the electrons return to the opposite ...
1 vote
3 answers
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Circuit resembling wheatstone bridge but not exactly [closed]

The below circuit resembles that of two individual wheatstone bridge arrangements as the ratio of resistances satisfy the conditions however we cannot come to this conclusion as potential at one end ...
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2 answers
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The current in an $LR$ circuit [closed]

I am trying to understand $LR$ circuits better. I am under the impression that inductors are resistant to change in current. So, the premise here is that the circuit was switched to side 1 for a long ...
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1 answer
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A question regarding determining internal resistance of a cell by using a potentiometer

In the given figure at null point J current does not flow through JD and AC but current does flow in the second circuit CDEF and primary circuit.My question is why doesn't current flow through ACFED ...
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8 votes
1 answer
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Gravity train with the help of batteries?

Imagine a gravity train (https://www.math.purdue.edu/~eremenko/train.html) that goes through Earth's crust from point A to B. The train could advance through the ride just by the force of gravity and ...
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How can I safely heat up a AAA battery? [duplicate]

I’m working on a science experiment in whether or not the temperature of a battery affects how long it will last. It’s the middle of winter where I am and I’m not quite sure how to safely heat up the ...
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How is the work done by a battery (when connected to a capacitor) independent of time?

We know that W bybattery = V(It) = VQ, which is time-dependent. But when the battery is connected to a capacitor then W bybattery = 1/2 (CV^2), where C and V both are time-independent, hence W ...
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1 answer
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Why is the net charge between two adjacent plates of capacitors in series considered neutral? [closed]

The right-most plate of C1 connected to the left-most plate of C2 is said to be isolated from the circuit. How is the left-most plate considered positive and the right-most plate negative?
1 vote
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Reverse polarity of cells connected in series and net EMF [closed]

When 2 cells are connected in series with reverse polarity, the net emf of the combination is difference of individual emfs, but clearly this is not the case practically, since cells connected in ...
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1 answer
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KVL in short circuit with 0 resistance [duplicate]

According to KVL, $\sum \epsilon = \sum RI$ in any closed loop. However, in an ideal circuit with no resistance, R is $0$, and hence $\epsilon$ must also be $0$. Does KVL not apply in this case?
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Kirchoff analysis in faraday law for RL circuit

Faraday law state that $$\epsilon_L=\oint \vec{E} \cdot d\vec{l}=-\frac{d\phi}{dt}=-L\frac{dI}{dt}.$$ So by kirchoff's analysis, isn't the equation would be like $$\oint \vec{E}\cdot d\vec{l}=0-IR+\...
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1 vote
1 answer
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Are we always allowed to treat an inductor as a battery with the same voltage?

When there is an induced emf, Kirchhoff's Loop Rule no longer is true, because electric fields are nonconservative when there is an induced current, as stated by Faraday's Law: However, I have seen ...
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What happens if ONLY one terminal of a cell is connected to a piece of conducting wire?

I've learned that current will flow to bring the potential of both ends of a wire to the same value if there is a difference in potential between them. Consider a cell of emf, , and negligible ...
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1 answer
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Dependence of work done by battery on circuit elements

The formula for work done by a battery is QV, where Q is the charge transferred by the battery. The battery maintains the potential difference between its terminals through oxidation and reduction ...
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Measuring voltage

Recently I was playing around with this circuit simulation, and I found that if I had a circuit with just a lightbulb and cell, then If I were to measure the voltage between the bulb and cell it gives ...
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3 answers
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Voltage in circuit

The way I understand voltage is the following: Its a measure of energy given to charge carriers in a circuit. Its a measure of potential difference, and it is the work in joules required to move 1 ...
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How do we assign value of EMF to a cell?

There are cells of different emfs like 1.5 volts, 2 volts etc. My concern is when we can not calculate the individual potential of any plate, or the potential difference between the plates by any ...
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-1 votes
1 answer
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Does current flow inside a battery?

When connected in a circuit, does current flow inside a battery. If yes, in which direction?
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1 answer
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Why the charge in each capacitors plate are equal in magnitude in series combination?

Suppose two capacitors are connected in series, I understand that external plates gets equal magnitude because of the batteries terminals, but how does the internal plates also get the charge with ...
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1 answer
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Cell EMF in parallel

My TB gives the following formula of emf of cells in parallel: $$\frac V{R_{eq}} = \frac{V_1}{R_1} + \frac{V_2}{R_2}+\frac{V_3}{R_3}+...$$ where $\frac 1{R_{eq}} = \frac 1{R_1} + \frac 1{R_2}+\frac 1{...
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The electric current in a circuit comprising a battery, an ideal wire and a few resistors

How will the electric current in this circuit flow? Assuming that the current starts flowing from the positive(+ve) terminal (Conventional current), will it flow entirely through the branch between ...
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1 answer
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Maxwell relation for battery undergoing reaction

I am trying to solve Reif Problem 5.16, and seem to continue to run into a barrier. I here give the problem and solution from the solution manual, as well as my work. This is not a homework question. ...
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1 vote
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How can this circuit be simplified in the first moments after the circuit breaker closes?

The book states that in this circuit after the transient the branch with the capacitor can be ignored while the branch with the inductance can be considered constituted only by a resistance. This ...
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3 answers
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Is there a contradiction at the top of this circuit? [closed]

Applying kirchhoff's second law to the first loop, the current in the upper branch remains determined and is $2.4$ A to the right (if $i$ is to the right then $-10i + 24 = 0$). Then the current in the ...
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Instantaneous current and average current

Imagine a simple electrical circuit with a battery and resistor. We know that the average current in any part of this circuit remains same . My question is : is the instantaneous current also same ...
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2 answers
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Why is lamp D off?

I understand the other lamps, but the answer for lamp d is that it is off as no current flows through it. I don't understand why? Please help.
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Good braking system for a mini car that can be triggered by a beam above the car that it will go past

I want to create a braking system for a mini car (essentially an aluminium body around 30cm long with 2 sets of axles with wheels (laser cut circles) connected to the end of each axle on the front and ...
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2 votes
2 answers
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EMF being equal through KVL

In the given figure,we connect three cells of different emf which are $V_1,V_2,V_3$ with a resistance $R$ in the first loop. Now suppose we emit current $I$ from $V_1$. $I$ gets divided into $I_1$ and ...
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3 votes
1 answer
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Using the sky and ground as a battery

Since there is a voltage difference between the ground and sky, shouldn't I theoretically be able to light a bulb by connecting one terminal to the ground and raising the other one to the sky (via a ...
0 votes
2 answers
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How is there current if there's no voltage?

Hi, I was trying to solve this problem, it asks to find the reading of ammeter. I think it has no resistance here. Does it mean that there's no potential difference, no voltage across ammeter? But how ...
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1 answer
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Current flowing from lower to higher potential

In the above circuit, two cells are connected in series to an external resistance $R$. Now the current going from point $A$ must return back to point $B$ of the cell. But for that it has to pass ...
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Working principle of the five(5) needle telegraph by Cooke and WheatStone

So I’m studying the history of telecommunications and came across the five (5) needle telegraph by Cooke and WheatStone. I want to replicate it but can’t get a grasp on the working principles. In a ...
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1 answer
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Is the positive terminal of a Daniell cell positively charged electrostatically?

Suppose, the circuit is open. I understood from @Dale's answer that the negative terminal of the battery is indeed electrostatically negatively charged. Suppose, it can have a charge of $-0.5C$. ...
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What happens to the electric potential if the amount of positive charge is greater than the amount of negative charge or vice versa?

In a Lithium-ion battery, the lithium ions are stored in the graphite layer while the electrons remain behind the electrolyte when the battery is fully charged. What if more lithium ions enter the ...
3 votes
1 answer
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What's the highest theoretical energy density in a chemical battery?

Is there a theoretical limit to how energy dense chemical batteries can be? How can one calculate them? And what stops us from reaching those limits?
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When two capacitors are connected in parallel, do they drain battery quicker?

My question is actually my answer to a question I asked myself i.e 'how does potential difference remain same for both capacitors which are connected in parallel, and not get distributed' When 2 ...
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How does 'symmetry' of a circuit allow us to find currents when a junction splits into 2 different resistors?

The book says what the picture shows. There's no parallel or series resistors and I could solve it with 4 different currents (if the top blue arrow is i3 and bottom green is i4) but that's a 4 ...
-1 votes
2 answers
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If a battery (cell) was elongated, will it have higher voltage?

Voltage is the potential difference between the terminals of the battery,and this potential difference is created by the work that the chemicals inside the battery had done. Also, work done is ...
1 vote
1 answer
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Circuit with internal resistance [closed]

A circuit is formed by connecting a resistor between the terminals of a battery of electromotive force (emf) 6 V. The battery has internal resistance. Which statement is correct when 1 C of charge ...
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1 vote
3 answers
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Difference between 2 points a circuit [closed]

I am asked to find the voltage difference between points A and B, namely $V_a - V_b$ of the following circuit: I don't exactly know how to approach this however. Is it as simple as going counter ...
0 votes
0 answers
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Heat dissipated in a capacitor network on switching a key

Suppose we have this capacitor network connected to a battery($V$) with the switch initially open. On closing the switch whilst keeping the battery connected, we find that some heat is dissipated. We ...
1 vote
2 answers
183 views

Would "Energy Vault" gravity battery work in water?

To be more specific, will one block lowered into water release the same amount of energy as in air?

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