Questions tagged [batteries]

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

55 questions
109 views

Does current flow when you connect a battery to earth?

Let's say that the earth has 0V and everything is ideal, does current still flow and why?
902 views

Voltage and Electric Field in a Circuit

I have a doubt regarding how the electric field acts in a circuit. I have been told that a normal cell creates a uniform electric field, but I find it a bit confusing. Let me explain my doubt with a ...
69 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 ...
40 views

How is the loop law applicable when I connect a battery with an ideal copper wire?

We would have a potential rise but where is potential drop? Considering wire to be having negligible resistance.
242 views

How to vary the current using batteries?

I am making a door bell as a school assignment. It works by having a solenoid produce a magnetic field which attracts a pice of iron attached on a conductor. when the iron is attracted towards the ...
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 ...
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 ...
30 views

New charge of a capacitor

How does the load of a charged capacitor vary when placing a dielectric between the plates while keeping the capacitor connected to the battery? If we have a capacitor that we have charged to the ...
69 views

How Can the Same Resistance Cause Different Voltage Drops?

Lets say we make two circuits, one a simple circuit connected to a 9 V battery with say a 9 $\Omega$ resistor attached,and one another simple circuit connected to a 9 V battery with a 9 $\Omega$ ...
121 views

Amount of energy that can be stored from Faraday flashlight / linear alternator?

You'll have to forgive me if this question is either extremely elementary or does not make sense — I am a civil engineer with little E/M physics background beyond high school education. I am working ...
145 views

Stacking batteries and electron flow

About Fuel Cells and Batteries: I understand the analogue with increased water height as two cells (battery or fuel) are connected in series. However if we for instance have two batteries contected in ...
182 views

Trying to understand the electric potential and potential energy

I am trying to understand some facts on electrical potential and potential energy. It is quite confusing in the text to say that the zero potential could be freely chosen for convenience. In that case,...
49 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 ...
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 ...
19 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 ...
81 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 ...
27 views

Does dropping a battery on the floor partially discharge it?

Can one mechanically discharge a battery? And if so, what is the mechanism responsible for that?
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: <...
26 views

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 ...
22 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?
77 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? ...
41 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 ...
29 views

Seperating Charges in a Cell

Sorry for not being detailed for my question here but how do charges seperate in a cell and when the electrons are pumped out of the battery does it return and become positive ? Yet again sorry if I ...
236 views

Charge distribution in series combination of capacitors

its a normal series combination of capacitors,only the inner plates are placed differently,one in the beginning and one in the middle,will it not alter the charge distribution ? that is if we will ...
279 views

Forces on charges moving through battery

In the attachment, which comes from a text "Introduction to Electrodynamics" by Griffiths. There are two statements: "Within an ideal source of emf (resistenceless battery), the net force on the ...
68 views

Conceptual scheme of circuits

What would happen if I were to connect two ends of a battery with a magic wire of no resistance? In the conceptual scheme of modeling circuit behavior there is always a circuit with a resistor given ...
57 views

Charging two wet cell batteries in parallel from an alternator

If I charge two wet cell batteries in parallel from an alternator and the smaller starter battery only needs a short charge to reach full state of charge and the service battery requires a long ...
71 views

What is the equivalent of the “amount of fuel” for a battery?

I am trying to make a performance diagram of an electrical powered device vs range, speed, etc. I want to compare it using the equivalent of fuel for a battery? I am not sure if it is just voltage... ...
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 ...
25 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

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....
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 ...
772 views

What happens in the RC circuit when being charged?

Say I have this RC circuit and at the start, the switch is off (current going from left to right and the starting point is just above the battery). I understand that then the capacitor acts just like ...
41 views

Why are(n’t) rechargeable batteries damaged by partial charging?

Originally asked in ElectricalEngineering.SE, but I was told Physics.SE might be a better place to ask. Over the years, I've come across websites and people with different opinions on the "correct" ...
175 views

Estimating the battery capacity using current power consumption and battery percentage

I want to estimate the current maximum capacity (in kWh) having the current power consumption (in kWh) and the state of charge of the battery (in %) available in a time series. I do not have a full ...
293 views

What are the physical limitations on energy density for a useful, safe battery, and are we anywhere near them?

Energy storage seems to be a fairly major bottle neck in technological development at the moment, especially for important things like clean-energy powered transport, but also for consumer goods. Are ...
156 views

Quartz piezoelectric battery

I'm designing a battery that uses quartz crystals to hold/produce a current for a long time using piezoelectricity. My question is: Would it be more efficient to have multiple small quartz crystals ...
53 views

Is this Thevinin equivalent of a voltage divider, correct?

Found the PDF version of The Art of Electronics (Horowitz and Hill) recently, and, having nothing better to do... I thought I'd give it a read. It wasn't long before I hit a wall (courtesy: my inept ...
52 views

I am looking for answers regarding a paper I am reading right now. I either found stupidly high values or strange SI unit. This paper is about battery charging, and the battery model used brings me ...
100 views