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

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Negative torque by an alternator during sudden change of load

I have often watched that when generators are started and suddenly when the load is increased, there is a drastic change in the RPM of the engine before it stablizes. From this it becomes clear that ...
12
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2answers
778 views

Does A.C. make the material through which it is flowing vibrate?

So recently I have been studying A.C. circuits and the graphs show that the current oscillates itself as a function of time. Now, according to me an oscillating body vibrates. Hence, the oscillating ...
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2answers
49 views

electrical field in coaxial cable

When getting the electric field between the outer and inner cylinder. why is it that we are only concerned with the field generated by the positive charge distribution on the inner surface and not ...
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1answer
52 views

Magnetic force on a charged particle doesn't affect total energy

So there's this sentence in a book I am reading. It states "When a charged particle is placed within a magnetic field, despite the magnetic force acting on the particle, there will be no change in the ...
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1answer
42 views

Principle of capacitor

It is said that second conductor reduces the potential of fist conductor and hence increases charge taking ability of first conductor My confusion... As per my limited knowledge it is electric field ...
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0answers
21 views

The Electric Grid: if AC load/generation causes frequency to change, what happens in a DC circuit where there is no frequency?

I've been trying to understand why, in the AC electric grid, frequency changes when there is imbalance in load and generation. Why doesn't voltage, or current, or power factor change? Why does ...
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1answer
26 views

Power current Electicity [closed]

When A 500 W electric bulb and 500 W heater operates at their rated voltages,the filament of the bulb reaches a higher temperature than the filament of the heater.The most important reason for this is ...
5
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1answer
73 views

What causes the buzzing sound when the electricity changes into heat?

When I turn on any kind of electric heating (kettle, cooker, heater, ...), it keeps producing a constant buzzing sound. What is the exact cause of that sound? Do the electrons of the electric ...
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1answer
42 views

How commutators reverse the direction of current?

I've seen this video and read this article about commutators but I still couldn't get how commutators reverse the direction of current.I would like an simple and intuitive answer.
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1answer
46 views

Flow of charge through metal wire [closed]

It is the flow of charge that matters -- electrical current is defined as the flow of charge. " -person W [...] if the flow of charge is all that matters; and electrons with their charge attached ...
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2answers
38 views

Why do people say that 'power flows' into or out of a component in an electric circuit?

Currently, I am learning about electric circuits, and how to apply the basic concepts of physics, like work and energy. But I keep running into the same phrase--on Wikipedia, my textbooks, everywhere--...
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1answer
80 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 ...
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3answers
387 views

What will happen to a man if he hangs from the power cable of train using one hand and secondly using two hands? [duplicate]

If a man holds and hangs from the power cable of trains with one hand, will he be alive or will he die if he holds and hangs from the electric wire using two hands without touching the ground ? I ...
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2answers
82 views

Why do some people support more electricity than others?

There is a game where people hold by their hands and two of them touch the electrodes of a shock box, then an electric current flows through them. I understand that since they are all making a single ...
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2answers
119 views

Why does internal resistance increase as current decreases?

Our class conducted and experiment to investigate internal resistance and terminal pd, using a cell, fixed resistor and variable resistor. The results were as follows: As the resistance of the ...
3
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1answer
105 views

Is Phone-Charging Plant Product Even Possible?

Bioo, a new company making the rounds in the press, claims to produce "electricity from plants' photosynthesis." Specifically, their website claims that a single potted plant with their integrated ...
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8answers
2k views

Why is capacitance defined as charge divided by voltage?

I understand that capacitance is the ability of a body to store an electrical charge and the formula is $C=\frac{Q}{V}$. What I don't understand, however, is why it is defined as coulomb per volt. Of ...
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2answers
75 views

How do we get 25kV at power stations? [closed]

Could anyone tell how we get a potential difference of 25000v at power stations? Is it due to the number of electrons present or the speed of the turbine or the large induced emf generated by the ...
3
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1answer
28 views

Why there cannot be induction current between plates of capacitor while discharging?

If a capacitor gets charged by induction through the plates, then why there is no induction current between them while discharging instead of displacement current ?
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1answer
51 views

What is the difference between the potential difference and potential energy of an electron?

What is the difference between the potential difference and potential energy of an electron? Let's take an example the potential difference (PD) across a resistor. if there's a current flowing, the ...
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1answer
21 views

Does the thermal expansion of a conductor contribute to its change in resistance when it is heated?

We know that the resistance of a conductor varies with a change in temperature and we are taught that this change occurs due to the change in resistivity of the material but does the thermal expansion ...
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1answer
17 views

Assumption of element for integration

In a round wire of cross sectional radius $R$, current density varies with the radial distance from axis of wire as $J=Cx^2 \, \mathrm{A/m^2}$. Find total current flowing in wire. ($J$ = Current ...
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2answers
65 views

Use of rheostat in a potentiometer practical?

in potentiometer practical why a rheostat is used in series to potentiometer wire? as we move the jokey the primary circuit current will also change. so is it to flow same amount of current by change ...
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3answers
138 views

Can we use magnetic energy to produce electricity?

Magnets attract each other with a force (magnetic force), because they possess magnetic energy. My question is, is there any way, by which we can convert that magnetic energy into electrical energy? ...
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0answers
23 views

Light bulbs Flashing on when disconnected

For the 2nd time I've had a lightbulb flash on in my hand after removing from the power socket. The first time the overhead light in my hallway was out for a couple of days before I got around to ...
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5answers
103 views

Could we use nuclear bombs to generate electricity? [closed]

it seems the biggest problem with fusion power is confinement. on the other hand, we developed a fusion bomb in just a few years. i was wondering if it could be economically viable to use nuclear ...
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3answers
120 views

If the electric field inside a conductor is zero then how does current flow through it? [duplicate]

I read in a book that when a conductor is placed in an electric field then the free electrons in the conductor will align in such a manner that an electric field is induced which is opposite to the ...
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1answer
53 views

Why are electrons negetively charged? [duplicate]

Why have we assigned a negative charge to electrons (and positive for protons)? I feel it would be easier if electrons were positive (thereby, protons negative)- electrons would flow in the direction ...
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4answers
111 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 ...
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0answers
19 views

With the help of a given charge is it possible to obtain a charge many times greater in magnitude

Consider a spherically conducting sphere. If a charge(say positive) is placed near the sphere, then it will lead to separation of charges inside the sphere.My question is, can we create charges more ...
2
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4answers
51 views

$ P = \frac {v^2}{R} $ derivation confusion [duplicate]

I have always had a confusion of why we use $ P = V I $ or $ P = I^2 R $ and not $ P = \frac {V^2}{R} $ for relating to power loss due to heat in high tension lines. I know there are a lot of ...
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1answer
32 views

How does the viscosity of a non Newtonian fluid (ooblek) affect its resistance to electricity?

I know the conductivity of water is based on whatever is dissolved into the solution, hence pure water does not conduct electricity. However, these ions in solution must also be free to move around. ...
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4answers
82 views

Which makes for a better equivalent capacitor? In series or in parrallel? [closed]

I understand how capacitors in series and in parallel work. However, I am wondering if it makes a difference, in terms of making a better capacitor that can store more charge, would you connect them ...
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2answers
72 views

How does increasing the distance between 2 copper plates in a circuit affect the capacitance? [duplicate]

We have been told that the voltage decreases, but not been given a proper explanation by my teacher. Can anyone shed some light on this? Also, does increasing the distance between the plates of a ...
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3answers
42 views

Flux - Scalar Multiplication in Integral?

No textbook and website seems to answer this so here is my question: When we have a scalar flux: I understand that you take the scalar product of the vectors. And I understand the need for using an ...
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1answer
48 views

A wall-outlet's hot-slot pulses energy in only ONE direction…toward the ground. How can this be considered ALTERNATING?

I'm trying to "see" electrical-energy transfer, at every viewing elevation (from the femto-scopic level to the macro-scopic level), all the way from the power plant (through the application) to the ...
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0answers
30 views

Power lines and cars

A live, active power line fell on the hood of my car. I was told to turn on my car and back away. Was this the proper advice?
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1answer
44 views

Loss when transfering electrial energy

Let's say we want to transfer a given amount of electrical energy $E$. We could do this with a voltage of $100\,\rm{V}$, but it's better to transform the voltage to $1000\,\rm{V}$, hence the loss of ...
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3answers
38 views

Why does the current in a purely capacitive AC circuit lead the voltage by 90 deg?

1.When we mathematically derive the expression for the current from a sinusoidal voltage source (v=V sin(wt)), we take the derivative of q=cv where c is the capacitance. The final expression we get is ...
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1answer
31 views

Generating electricity in space with magnets

Assuming we have a very strong magnet of strength B and of uniform mass in space inside a coil of copper wire of turns N. Also, assuming that the magnet spins at the centre of the coil with no ...
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1answer
46 views

Does AC-current reverse direction only in the main circuit (the powerplant-to-powerplant circuit)?

I'm trying to "see" electrical-energy transfer, at every viewing elevation (from the femto-scopic level to the macro-scopic level), all the way from the power-plant to the application. The question ...
0
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2answers
45 views

Why does a rotating aluminium disc slow down when a current carrying coil with iron core is held above it?

What I don't understand is it the Emf induced that slows down the disc or is it a force.
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1answer
27 views

High Voltage Powerlines - clarification of energy loss

I've been having a bit of trouble understanding the High-Voltage powerlines. If I was sending power from $A \rightarrow B$, we have: Ohm's law $V = IR$ Power lost in the form of heat $P = I^2 R$ ...
11
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3answers
832 views

Does electricity have an associated entropy?

One can certainly measure entropy changes associated with the generation of electricity, but does electricity itself have an associated entropy (maybe related to voltage, current etc.)?
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1answer
49 views

Why does the Emf generated by a magnet going through rings of coil generate a sinusoidal curve of Emf vs time?

I am having trouble writing the reason for the part of the curve to cut the x axis at Emf = 0 and when reason for curve to form max and min peaks.
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1answer
97 views

Conceptual Doubt Regarding Electric Circuits [closed]

There are a few questions which have always bugged me. Unfortunately, due to time constraints, I end up memorizing an example, hoping to imitate that knowledge in an exam question. Consider the ...
0
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1answer
28 views

Is it possible to express Fleming's Left Hand Rule and Right Hand Rule in terms of vectors?

I recently studied Fleming's Right Hand Rule and Fleming's Right Hand Rule for electromagnetism (For locating direction of Force, Magnetic Field and Current). Using my hands to find the direction is ...
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1answer
37 views

charge on the capacitors

When we connecting a capacitor to a battery of $V$ volts. After it is completely charged, it is disconnected from the battery, and if we connected to another capacitor. In this case, there is no ...
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2answers
301 views

Why is Electric field flux through a closed surface in Gauss's law not zero?

I learned that the vector flux through any closed surface is always 0. So if you have a sphere(closed surface) and you put it in an uniform electric field, then the total flux is 0. However, the ...
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1answer
67 views

if the voltage is the driving force of the current, how can it lead or lag?

Correct me if I'm wrong on this, but up till now I've assumed that the voltage across a resistor could be seen as both the energy lost by a current passing through it and the energy needed for a ...