Questions tagged [batteries]

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

402 questions
29 views

How cell drives electrons to flow in a metal wire?

This was my approach using some facts I'd known- At cathode and anode of a cell reactions take place making positive terminal positively charged and negative terminal negatively charged I.e. there are ...
349 views

Do battery electrons only move if there is a positive terminal at the end of the wire?

I'm sorry if this question may seem wrong in many cases. What would happen if we had a wire with the length of 1 kilometer that connected the two terminals of the battery? Do electrons care if the ...
62 views

RC circuit series and parallel [on hold]

R and 2R are in parallel. 4R and 3R are in parallel. I dont know where to go after calculating the the parallel Rs. Do you become in series? If so, how? It is right after the switch is closed. So ...
78 views

Telling if Capacitors are in Parallel or Series

So C1 and C2 are in series. But if each one is placed in red boxes, they are in parallel? It's confusing going jumping between current, capacitors, and resistance. For me it's kinda confusing ...
94 views

Internal resistance and Instantaneous current?

Okay, this would probably seem a pretty basic doubt but I can't understand this thing. I know that when the current is not flowing in the battery the voltage across the terminals is the emf of the ...
21 views

Concentric cylinder cell constant

For a concentric cylinder cell (with liquid dielectric), mathematically the equation for the cell constant will always yield a lower value than for the parallel plate case for the same volume of fluid....
35 views

Powering an electromagnet for a long duration

Looking to power an electromagnet requiring 12 DC volts at 4 Watts, and wondering what size battery I would require to do this for 4 weeks? My maths so far is, and I am not sure this is correct: <...
34 views

Work done by battery in moving charge $Q$ in circuit

why work done by a battery in circuit is potential diffrence across plates times charge flown through body. W=Qε(ε is emf of battery) although there are heat and other loses ? and another that my ...
38 views

What is the field that moves charges in a resistor?

We say a potential difference moves charges in a resistor.. i want to understand it in terms of field. What charge distribution produces a field in the resistor? True, the cell produces a field.. but ...
56 views

Work done by battery?

Why the work done by a battery is Q*V where V is emf of battery and Q is charge that is made to flow in circuit?please explain detail? explain and write the formulas
1k views

Why is there no current between two capacitors connected in series?

I want to ask a question about the figure below. Why the current does not flow from $-Q$ term to $+Q$ term or from a to b since there is a voltage?
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When the external resistor increases in temperature, why is the calculated value for internal resistance higher?

Say we had a circuit with a cell (with internal resistance)and an external resistor of 10 ohms as shown: The 10 ohm resistor then increases in temperature, leading to an increase in resistance in ...
84 views

Why does the potential difference across a type of parallel circuit not act like a potential divider? [closed]

Image credit (Q3) In this attached circuit, when $R_1=0\Omega$, I am failing to understand how the two cells affect the potential difference across the central resistor R3. I understand that ...
70 views

Voltmeter reads zero with two same batteries connected in series [closed]

this is an a level physics question, can someone here please explain why voltmeter reads zero and how changing resistance of variable resistor effects voltmeter reading. The main concept i want to ...
67 views

Does the voltage of the battery change if you use it? [closed]

If you use the battery to charge a capacitor does the voltage of the battery decrease or still the same? Does the voltage of a capacitor decrease if you use it to charge another capacitor?
37 views

Kinetic energy and current

When a battery is connected to a resistance circuit, we know that it loses energy because heat is emitted as a result of the collisions between the electrons and stuff, but my question is, is the ...
39 views

Finding the charge on a capacitor (RC circuit)

I am having trouble finding the charge on the capacitor for $t\rightarrow \infty$ after the switch has been closed at $t=0$. I already know the current $I$. I also have to find out on which sides the ...
68 views

Resistors parallel to short circuit

I have a trouble solving this problem. (Actually, each resistor is not parallel with the bottom wire since the voltage across each of them is different with that of wire.) In the manual, the bottom ...
236 views

Theoretical physics for better batteries?

It is Earth day, so I started thinking about the theoretical physics problems that could help reduce greenhouse-gas emissions and fight climate change. We actually have a reasonable range of ways to ...
43 views

What do we mean by positive terminal and negative terminal?

What do we mean by positive terminal and negative terminal of battery ? What is the electric potential of both positive terminal and negative terminal ? Does positive terminal mean positive electric ...
104 views

Would Kirchhoff’s rules not hold in this circuit?

On my E&M test I was given the circuit diagram below and asked to find the charge on the capacitor after a long time or as $t \to \infty$. In class we had used Kirchhoff’s voltage rule on the ...
43 views

How do electrons gain energy in a cell?

When electrons reach the positive terminal, how does the cell do work on them? I’ve read in a book that states voltage is literally the push that the cell exerts on electrons, which thus does work on ...
102 views

Battery operation, charge and discharge processes misconceptions

I'm trying to elaborate a simple and concise explanation (and conceptually correct) of how a battery charges and discharges, and why we say things like "the charge stored in the battery is x Ah". For ...
28 views

Calculating energy capacity of a battery

I understand that you can easily calculate the energy capacity of a battery simply by multiplying the mAh rating by the Voltage. However, my question is how do the manufacturers calculate the mAh ...
119 views

Nernst Equation and Energy

I have a question regarding the Nernst equation and energy in a system. I know this is also a chemistry question, but I was interested in the thermodynamics (the energy of a system), so I decided to ...
30 views

How to choose the method of circuit analysis?

I was just doing some revision, and I was wondering how to figure out which method to use for solving a given circuit? I tried using mesh analysis on the attached circuit but I got it completely wrong....
43 views

Does Stopping Voltage actually produce 0 photocurrent?

The stopping voltage is the voltage applied across the photoelectric plates to measure the maximum KE of ejected electrons. This is as the electric field will apply a force against the velocity of the ...
24 views

Question about amp-hour and batteries in series

I am a little confused about this wiring batteries in series and parallel and the effect of this on total time that these batteries can last(I suppose this is called amp-hour, correct me if I'm wrong) ...
78 views

Different batteries in a parallel circuit

I have come across this question in my physics textbook. Two batteries are connected in parallel to a resistor (see the above image). The first battery generates $U1 = 9V$ of voltage and its internal ...
85 views

RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam; A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
67 views

What happens when a battery is dead?

While studying circuits I am having a question that when we say a battery is dead.Do we mean that the voltage difference between the ends has become zero?If no,then what actually happens?
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Can anyone tell me why the answer to this question is D? [closed]

I think the current will go through earth wire but my physics teacher told us the current will continue to flow through the circuit.
70 views

Practical usage of batteries connected in parallel

Is there any practical usage in real devices for connecting batteries in parallel? Or is it more a theoretical construct? It seems to me that only batteries in series are used nowdays.
34 views

Empty and fresh battery in series

If you have 2 (e.g. 1.5V) batteries in series and one is dead/empty, what is the reason why a device is not working? Lack of voltage (1.5 + 0 is simply not enough for the device to operate)? From my ...
54 views

Why did a 12V battery affect my motor more than two 9v batteries in series?

In class, we made a coil of wire and used it to make a simple electric motor with a magnet. I put two square 9v batteries in series for a total of 18v to power the motor. I then used a larger 12v ...
82 views

The importance and the role of a switch in an electrical circuit

There is this simple test: Three identical bulbs are connected in the circuit illustrated in the figure. When switch $S$ is closed: a] The brightness of $A$ and $B$ remains the same, while $C$ goes ...
38 views

For a real battery, why is two identical bulbs in parrallel slightly more dim than just one in series

Image for reference: \begin{align} &r = 0.8\,\Omega\\ &\mathscr{E} = 1.5\,\mathrm V\\ &A = B = 6\,\Omega. \end{align} The current when the switch is open, the only other resistor is ...
29 views

Direct current electric circuit

Why when I reverse one of the three batteries in a torch light, the bulb does not light up? The three batteries (one of them is reversed) and the bulb suppose to form a closed loop. According to ...
35 views

Why do we subtract the voltage of the resistor from the emf voltage to find the terminal voltage?

I attached an image of a question from homework. I calculated the current in step 1) and then I calculated the voltage of the resistor. But why do I need to subtract that voltage from the emf voltage ...
71 views

Doubt while simulating electric circuits

Today, I was simulating DC electric circuits just for knowledge and fun using PhET interactive simulations. But I'm having trouble understanding these circuits which I made. I think that both these ...
38 views

Voltage when lamp burns out [closed]

In the question below, shouldn't the voltmeter read zero V because the circuit is broken and there is no current flowing? (the answer in the text is 12v)
20 views

Question about electrochemical reaction in fuel cell

The electrochemical reaction on the anode side of a fuel cell can be expressed as hydrogen split into hydrogen protons and electrons. I'm doing some research about the electrochemical reaction in a ...
85 views

Why doesn't the flow electrons occur in a broken circuit?

Take a battery and connect a small led bulb across it with the help of two wires. The bulb will glow, but if I cut a small piece of wire from any part of the connecting wires,the circuit will not work ...
38 views

Intuition behind swapping the known and unknown resistance in a slide wire meter bridge

Today I was learning about wheatstones and balanced meter bridges. But while learning about the sources of error while working with the meter bridge (measuring unknown resistance), I couldn't ...
137 views

How do voltmeters measure work done over a component?

In my physics class, we were shown the picture below to measure the current and potential difference through a component. We were told that the resistance of the ammeter is as low as possible, and the ...
2k views

Does the resistance of the voltmeter affect the behavior of this circuit?

I have this setup. It consists of a battery of no internal resistance with voltage $V$ and a resistor with resistance $R$. It also consists of a voltmeter of some (not so large) resistance as good ...
50 views

Power in a simple electrical circuit [closed]

In this picture, as we know power due to heating of the resistance is $V^2/R$ . Now, if we add a parallel resistance to the circuit, the power dissipated through this resistor is also $V^2/R$ ...
50 views

Voltmeter connection across motor

I want to measure the voltage(potential difference) acorss the motor A. Where should I connect the voltmeter? I am confused between two possibilities: between X and Y (between two ends of the motor ...
Well I was just wondering how a copper-zinc battery works, with electrolyte an equilibrium of water and NaOH. It says that NaOH is dissolved (I understand that) into water forming H$_4$O$_8$Na+ ions ...