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

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2
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4answers
382 views

Why doesn't current flow when the wire is open?

I realize this may be a hard to answer question but we are currently studying current in our school. One thing that struck me was why the heck doesn't it flow when the wire's closed? When you connect ...
0
votes
1answer
448 views

The Voltage and Current of a Discharged Inductor at the Instant the Switch is Closed

The figure shows an LR circuit with a switch and a 240-volt battery. At the instant the switch is closed the current in the circuit and the potential difference between points a and b, Vab, are ...
0
votes
0answers
168 views

Why are magnets attracted to negative side in battery

I have been experimenting with magnets, and built an Homopolar motor however it works but the magnet only attracts the negative side of the AA battery (the flat side of a battery) which I thought was ...
1
vote
2answers
117 views

Is battery capacity proportional to Ampere-hour in every case?

Suppose I have two batteries one inside the laptop with 2.5 AH giving a backup for around 2 hours. The battery is external inside a UPS system with 7.5 AH. Since it has thrice the capacity of the ...
0
votes
3answers
256 views

Capacitance: How to increase total charge drawn from a battery?

I can't seem to find any information about how parallel capacitors or capacitors in a series affect how much a capacitor can charge, not in my textbook or online. Here is the question I am trying to ...
3
votes
1answer
354 views

If I charge a battery using a much higher current, can it explode?

If I have a 12V 4Ah lead acid battery and use a battery charger that, let's say for example, can charge 10A, 50A, or 100A. If I theoretically turned it to 100A will the battery explode? I understand ...
2
votes
3answers
562 views

Why doesn't Lenz's law predict the behavior of a rod on springs in a magnetic field?

This comes from one of the free response questions from the AP Physics B 2014 exam. 5. (15 points) A conducting rod of mass $m$ and length $L$ hangs at rest from two identical conducting ...
7
votes
1answer
255 views

Empty batteries magically resurrect after reinserting them

It happened to me quite often (most recently with my wireless keyboard) that a battery stopped to work and then, if I unplug it and then plug it back in it works again, not just for a couple of ...
2
votes
2answers
72 views

Why are large batteries described by their power?

Reading about renewable energy sources, I came across the idea to use huge batteries as a temporary storage to be able to deal with the fluctuations that e.g. solar panels might produce. The most ...
0
votes
1answer
40 views

High Current at first and then steady from a battery

I just came up with a question, When a battery is connected to a circuit, the current first suddenly peaks up and slowly goes down to a steady value. Why is it so? I have not actually observed this, ...
1
vote
1answer
69 views

Battery Capacity vs. Battery draw

Pardon my ignorance but I just can seem to find an Answer to my question and I hope that you can help me. What is the equation for calculating how long a Lithium Battery can supply a device? For ...
6
votes
3answers
4k views

What happens if I throw a battery into water?

Today I have by accident thrown a AAA battery into a bucket of water. I fished it out of the water immediately (within 20 seconds or so) and nothing notable had happened and the battery is still full ...
2
votes
1answer
123 views

Do batteries lose charge?

Say I have a charge of +q and -q on the positive and negative terminals of a battery. If I connect wires to each terminal, but don't connect the wires (essentially creating an open circuit), the ...
1
vote
1answer
84 views

No-answers-found Li-Ion battery questions [closed]

Background Ive spent almost 7 hours researching about li-ion batteries because my Galaxy S2 only lasts 2 hours with all turned off and only 40 apps installed (removed system apps and bloatware) and ...
3
votes
1answer
134 views

Is it possible that a battery goes flat faster in a cold environment?

I own an old iPod Classic with original lithium-ion polymer battery and I use it primarily while running. Recently I discovered that when a temperature outside is low, usually below 5 C degrees, the ...
5
votes
4answers
3k views

How electron movement produces current,instead of having a slow drift speed

Just need a clarification here, how the current is produced due to the movement of electrons, in an external circuit,having a very slow drift speed. Normally in a battery there is high potential ...
4
votes
3answers
261 views

Why do batteries work?

Consider diagram A. In diagram A a car is at the top of a cliff. Gravity is pulling it down, but it does't move since its on a flat surface. Even though it would be at a lower potential at point B, ...
0
votes
1answer
563 views

How does battery cell size affect voltage drop for a fix current load? [closed]

For a fixed current load, will the voltage drop be larger in a small cell or a big cell battery? Why?
1
vote
2answers
56 views

Understanding watts available in miniature batteries?

I am doing a project with some small miniature incandescent light bulbs (like a CM7333). Sorry for not providing more links, the system will only allow 2. The power source is a E11A battery. The ...
1
vote
1answer
602 views

Circuit with inductor and lightbulb when switch is turned off?

I want to know what happens with a lightbulb immediately after a switch is turned off. We're talking about a circuit with a battery (AC), an inductor, a lightbulb and a switch. I need to know it in ...
0
votes
2answers
158 views

Batteries connected in Parallel

"If we connect two batteries in parallel, the battery with higher voltage will discharge into the other one." What is the intuition behind this?
1
vote
2answers
386 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 ...
0
votes
1answer
165 views

How to calculate cost of AA accumulator charge? [closed]

I would like to calculate how much it will cost to change AA accumulator. Is it really cheaper than usage of batteries (don't consider ecology question as of now)? Let's say I have the following ...
3
votes
2answers
3k views

Why is there no current flow when i connect two opposite terminals of two separate batteries

I don't understand this..maybe there is something wrong with my understanding of battery or electricity. I am learning about electricity more deeply this time. So please spare with me... So lets ...
0
votes
2answers
1k views

What do we mean exactly by the positive/negative charges in cathode and anode?

In batteries, what exactly do we mean by negative and positive charges? My understanding is that the negative charge of the anode is basically an atom with an extra electron in the last orbital and a ...
0
votes
1answer
298 views

What is the difference between a battery and a “polarized” charged capacitor?

I know that the main difference between the two is that a battery can provide a constant voltage whereas a capacitor's voltage decreases as the charge stored decreases. But what about the internal ...
-1
votes
1answer
757 views

Hard circuit problem [closed]

I want to find the p.d. between points A and B. I'm not sure how to approach this problem though, could I have a hint?
8
votes
4answers
3k views

Why aren't betavoltaics and alphavoltaics batteries widely used?

Betavoltaic batteries are devices which creates electricity from beta radiation of a radioactive material. Alphavoltaics operate similarly, using alpha radiation. The concept was invented roughly 50 ...
19
votes
3answers
589 views

Why can't batteries be charged quickly?

Charging of laptops, cell phones take so much time. Why can't we make such batteries easily/commercially which are charged more quickly? What's the thing behind this limiting?
-2
votes
2answers
398 views

Basic Physics Question [closed]

I'm having a difficult time answering this question. I think I'm just converting the units wrong somewhere: You're the CEO of a courier company, and you decide to select an electric car for your ...
2
votes
0answers
156 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 ...
-3
votes
1answer
234 views

Whether a battery store energy or simply it makes energy? [closed]

There're some easy concepts which I don't get exactly in my mind. I've been studying these things for two years of my engineering but they still bother me. Battery is one of them. Can someone explain? ...
0
votes
1answer
89 views

Cell connections

I have an UPS with two 6V batteries connected in series. Is it possible to use the same system (UPS) to charge another two pieces of 6 volts battery if all the batteries are connected in parallel to ...
2
votes
2answers
284 views

Battery and current confusion?

How exactly does a battery produce a current in the circuit connected across its ends? I dont want to know the chemical reactions in the battery core, but just the essence of it. I believe it doesn't ...
0
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4answers
121 views

Capacitors' working in a circuit

Does charge in a capacitor containing circuit stop flowing when the potential of the capacitor becomes equal to the potential of the battery??
5
votes
2answers
9k views

Why do two connected 1.5-volt batteries become a 3- volt battery?

Why two connected 1.5 volt battery become 3 volts? If one battery plus side is connect to minus side of another battery, there should be a current flow between them until no free charge move anymore, ...
1
vote
1answer
601 views

Why should a battery not give current in order to measure EMF?

Emf is the "potential difference (PD) across the terminals of a battery when it is giving no current to the circuit." What does "when it is giving no current mean"? Will the PD across the terminals ...
3
votes
4answers
252 views

What is a “gravitational cell”?

I am not a physicist, and I don't understand the details of electromagnetism. Anyhow, I was looking for how the batteries work in Google. So, I came across this article: "How batteries work: A ...
4
votes
3answers
23k views

Different batteries connected in parallel

If we have 2 batteries one of emf x and the other is of emf y and we connect them in series we get an effective emf of x+y. But what if we connect them in parallel, how to calculate the emf now?
1
vote
2answers
341 views

Simple ohms law on a battery ? Paradox or conceptual error?

Suppose we have a regular pencil battery which supplies DC voltage $V$. Say we take copper wire and connect the ends of the battery to an $R$ ohms resistance. Then Ohm's law tells use the current in ...
1
vote
4answers
4k views

Capacitor Charging and Discharging when connected to the ground

When we charge a capacitor using a battery and then remove the battery, the plates of capacitor becomes charged. One holds positive charge and the other one gets equal negative charge. o. k. ? Now ...
5
votes
2answers
3k views

How can a circuit function with two negative battery terminals facing each other?

Here is a drawing of the circuit that is confusing me: I don't quite understand how batteries work in this diagram. If a battery has a negative and positive terminal, there must be a barrier ...
2
votes
2answers
169 views

Static discharge out of 3 volts button battery

I am starting to get interested in static electricity I have found this which is very cool but I do not know how I can control the output voltage. ...
1
vote
2answers
202 views

Why isn't this capacitor charging?

Let's say you have a parallel plate capacitor and you connect one plate to the positive terminal of a battery and the other plate to the negative end. So this is like a static situation, you have a ...
2
votes
3answers
650 views

Can I charge a capacitor using 2 batteries?

1 capacitor, 2 separate batteries (Battery A and Battery B). Connect A+ to one side of the capacitor and B- to the other side of the capacitor. A and B are not connected, there is no closed circuit. ...
7
votes
3answers
5k views

Path of an electron through an electric circuit

When a potential difference is applied across a conductor, and if an electron moves from the negative terminal of the battery and reaches the positive terminal, then I want to know if the electron ...
-1
votes
1answer
4k views

Can I use AA batteries to charge iPhone? [closed]

Technically, 4 AA batteries will give out ~5V, which is equivalent to USB. Can you use 4 AA batteries to charge an iPhone, without messing up the Li-Ion cells used on iPhone? So my question really ...
1
vote
2answers
2k views

How can you calculate (or convert) the Wh of a capacitor whose energy is given in Farads

When trying to compare the energy in a battery to the energy in a capacitor, the units don't match up. How can one compare a battery whose Ah are 10 and Voltage is 3 (for a total of 30 Wh) to a ...
5
votes
3answers
1k views

What's the difference between Capacitors, Ultra-Capacitors and Batteries

Capacitors are known to hold and release energy very quickly, unlike the slower release that batteries exhibit. If one were to bunch many (1000's of) capacitors together could they function as a ...
4
votes
3answers
5k views

If we charge a capacitor can we discharge it into a battery?

I have read that we can charge a capacitor using a battery, but can the vice versa happen? My project needs to show a battery being charged through a fully charged capacitor.