All Questions
31 questions
0
votes
3
answers
126
views
Potential drop against internal resistance of cells in combination
Suppose two cells of emf and internal resistance e1, r1 and e2, r2 respectively are connected in series. The negative electrode of 1st cell is connected to negative electrode of the second cell. Why ...
- 1
2
votes
2
answers
234
views
Why can't I observe a voltage between two capacitor plates when only one of the plates is connected to a battery?
Let's say I have a battery and a capacitor that is neutral. Now I connect the battery positive terminal to only one plate of the capacitor. From what I know, there is a potential difference between ...
- 23
0
votes
1
answer
200
views
EMF of source depends on the charge and the path then what do we mean when we say EMF of a source is $\epsilon$?
EMF of an EMF source (a battery for example) is defined as the work done by the non-conservative force(s) on charged particles as it passes through the terminals of the source divided by the charge of ...
- 510
1
vote
1
answer
663
views
Equivalent EMF of unequal cells connected in parallel
I'm aware of the formula to calculate equivalent EMFs of 2 cells connected in parallel as shown in the top figure. But what happens if we switch the polarity of one of the cells? Shouldn't the ...
- 33
4
votes
1
answer
977
views
How batteries create voltage?
I am trying to have a more fundamental understanding of electricity and specifically what voltage is.
My memory of highschool physics was that a battery has an excess of electron on one terminal, and ...
- 221
0
votes
2
answers
49
views
Is it possible to charge positively an object using only the higher voltage terminal of a battery?
If electrons move through higher voltage, would a neutral conductive object get charged positively if I were to connect it to only the positive terminal of a battery?
As in, would the electrons would ...
- 503
2
votes
2
answers
476
views
Voltage and Potential in a battery
I would like to think that voltage is like the force provided by the battery to move. When electrons are near the negative terminal of a battery, they experience a repulsive force which makes them ...
- 367
0
votes
2
answers
86
views
Is battery a capacitor that's being continuously charged?
Is it correct to say that a battery is like a capacitor which keeps being charged?
- 282
4
votes
5
answers
8k
views
If I touch the "+" side of a high voltage battery, will I get shocked?
Voltage is electrical potential difference between two points. When these two points are connected using a conducting material, current flows. So far so good?
Let's think of a high voltage battery (I ...
- 282
1
vote
4
answers
158
views
Quick question regarding the meaning of Voltage of a Battery
Is the voltage of a battery simply the work necessary to move a unit charge from one extreme of the battery to the other?
If this is the case, then when calculating the voltage of a battery the ...
- 379
0
votes
3
answers
241
views
What is the connection between electric field and a battery?
Ok I'll start my question with laying some background: (Correct me if I'm getting things wrong - but don't be picky).
Put electro-magnetism aside for this discussion - an electric field is some space ...
- 282
0
votes
2
answers
645
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What does a battery produce? Is it Electric Potential Difference (EPD) or Electro Motive Force (EMF)?
I have read a lot of posts about Electro Motive Force, Electric Potential Difference and their differences, but I still confused. What I know is that EMF produces a EPD and keeps it constant, then ...
0
votes
2
answers
324
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 ...
- 59
1
vote
0
answers
876
views
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 ...
user272011
0
votes
3
answers
99
views
What does an incompleted variable resistor mean physically?
In the diagram below, the resistor has three terminals I believe. Now in this circuit, my book tells me, that only two terminals are being used (to alter the resistance by sliding the metal contact). ...
- 350
0
votes
3
answers
320
views
How is this a parallel circuit?
I understand that here, the current has a choice to flow through one resistor and back to the terminal WITHOUT going through the other.
Is this, a parallel circuit? I don't get it. Sorry if this is ...
- 350
1
vote
1
answer
226
views
Why aren't salt water batteries used to power cars instead of lithium-ion?
I know salt water batteries are less efficient than lithium-ion, but water is safer, can be found anywhere, is cheap and 100% ecological. Even if it doesn't last long, you can refill anywhere. Why can'...
- 1,029
1
vote
3
answers
136
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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 ...
- 497
0
votes
2
answers
4k
views
What makes fruits conduct electricity?
I'm sure most people are aware of the fact that certain fruits and vegetables are capable of generating electricity. But my main question is:
1. What are the names of such fruits that conduct ...
- 109
3
votes
1
answer
2k
views
Why would 4 batteries in a device not drain equally? [closed]
I noticed a motion sensor light was weak so I assumed the batteries were dying and removed them. To make sure I was right, I tested the 4 D alkaline batteries. One was completely dead. One was on the ...
- 41
1
vote
2
answers
8k
views
Batteries in series vs parallel
As fa as I understand it, two identicle batteries in parallel will give double the amperage than just one battery and two batteries in series will give double the voltage. If my understanding is ...
- 31
0
votes
2
answers
298
views
Why can a Faraday pail not be cumulatively charged from a battery?
First consider a commonly performed Faraday ice pail experiment and my question will naturally follow:
If a charged object is allowed to touch the inside of a Faraday Pail, the charge will be ...
- 105
-3
votes
3
answers
342
views
What is voltage in a circuit?
What is voltage in a circuit?
I know potential difference is the difference of potential energy of two points in a space affected by an electric field per unit charge.
Why is there voltage in a ...
- 123
2
votes
1
answer
247
views
What do the batteries actually do to the electrons?
I am plagued by this simple question that what force exactly causes the motion of an electron in the middle of a lattice of electrons of a wire?
a. Is it an electric field created inside a wire due to ...
- 178
0
votes
4
answers
10k
views
Electrons moving in a simple circuit with a battery and a light bulb
I believe my understanding of electric currents is flawed and want some help to clear up a few things. I'm not looking for a precise scientific understanding, but to understand the basics. I'll try to ...
- 319
6
votes
3
answers
2k
views
Why is the voltage of a battery equal to the emf?
We know that there is an electric field inside the battery that works against the moving electrons of a circuit. But there is also the chemical force of the battery that at some point become equal. ...
- 7,860
3
votes
1
answer
1k
views
Multimeter reading between wire & air
Why does a multimeter show 10-20 V(AC) when I connect one of its cables to the hot wire of a 220 V(AC) plug while the other cable is in the air? Also why does this not happen with a 5 V battery? (It ...
- 33
0
votes
3
answers
241
views
How is voltage increased from a battery?
I have recently watched a video about a powerful Octa-copter that uses 30,000 Volt brushless motors to propell, the batteries however look quite small about a 19v laptop battery. How is the voltage ...
- 757
2
votes
4
answers
7k
views
How can there be a voltage when there is no current?
I'm told at school that the Electromotive Force (e.m.f) of a battery equals the potential difference between the terminals of the battery when there is no current.
How is that possible? How can there ...
- 121
4
votes
2
answers
8k
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 ...
- 141
1
vote
2
answers
1k
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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 ...
- 1,352