# Tagged Questions

The study of the presence and flow of electric charge. Charges, currents, fields, potentials.

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### Strange electrical circuit

This is a question I would like to have an explanation with: It's in this PDF, question 9. In that circuit, if switch 1 is closed, bulb A burns normally. If 2 is closed as well, do other lamps ...
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### Will there be any force of attraction or repulsion between an electrified body and a non-electrified body?

Up to my knowledge an electrified (charged) body can attract a non-electrified (neutral) body. I thought this because, when we bring a charged (suppose negatively charged) body near a neutral one. ...
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### How does current work

In all diagrams i have ever seen of circuits it's implied that electrons travel through load/bulb and bulb makes light/heat. Now there is a problem here...because of this implied logic i assumed more ...
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### Does a battery in a vacuum produce a current?

I've always assumed that the strong resistance of air is the reason there is no flow of electrons between the terminals of a battery until a wire is connect. However, in a vacuum there is no resistive ...
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### Why are electrons defined to have negative charge? [duplicate]

We normally think of the "default" or "root" state of things as being on the positive side of the spectrum. For example, we don't normally use a + symbol to ...
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### why does headlights dim when a starter motor is turned on

okay first of all, what exactly does the starter motor do? does it increase the current flow and decrease voltage? and does starter motor have its own internal resistance? i understand how there is a ...
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### Can an AC magnetic field be measured by a hall probe?

Many hall sensors on the market have a datasheet that explain the proportional relationship between the analog voltage that is outputted and the relative gauss/tesla reading (for example: 2.5mV = ...
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### Inductor rise time and inductor wire length

So here is an interesting question about inductors or coils in general. Suppose you had a inductor which was 12 inch's in diameter and say 12 inch's in length and has 100 turns of wire. The total ...
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### Which physics subjects should a math major follow if s/he's interested in Smart Grid Networks? [closed]

I study mathematics and I would like to work on Smart Grid Networks in the (near) future. I would like to do so by applying optimization theory, percolation theory, Markov chains and more to problems ...
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### Why does connecting a battery's positive terminal to the negative terminal of another battery not create a short circuit?

This is a question regarding the physics behind the observation. I have guessed the answer to the question, but I may be wrong, so I want to wait for the responses before posting it. Some major ...
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### Self-sustained vs. non-self-sustained discharge systems

I don't quite understand what a self-sustained discharge is. I figure it means that the processes involved are self supporting and generate themselves, so that I don't have to put energy into the ...
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### About thermionic emission

Does thermionic emission have any limits? If we continued heating the metal plate can it reach a charge of 1 C ? Will the work function increase as the charge of the metal plate increase?
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### What can justify the decrease of the electrical conductivity with the increase of light intensity?

I have currently been working with a sample that "appears to" decrease its resistance when I cover it and protect it from light. Basically it presents the opposite behaviour of a photoresistor. What ...
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### Conductor resistance calculation method

1. What are the variables that effect on a conductor resistance (I mean all of them)? First of all I would like to say that I know how to calculate the resistance of a conductor using the method ...