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

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Finding the resultant electric field intensity?

Q: Two charges Q1 = 4×10^-7 and Q2 = -8×10^-7 are placed at the two corners A and B of an equilateral triangle ABP of side 20 cm. Find the resultant intensity at P? I calculated the electric field ...
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1answer
25 views

Wind turbine impact on cars fuel consumption

I have question that I still can't resolve. How much cars fuel consumption rises(l/100km) if I attach 1 kW wind generator to cars body? How can I calculate that and what do I need to know? ...
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3answers
24 views

Ohm's law and an ideal voltmeter

In an ideal voltmeter there is infinite resistance so because of which no current is flowing through it and the voltage reading is not affected. The ohm's law stated that V = I * R In an ideal ...
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0answers
31 views

why was necessary the discovered of electromagnetism? [on hold]

Need to know much more for the necessity of electromagnetism. http://www.ck12.org/physical-science/Discovery-of-Electromagnetism-in-Physical-Science/lesson/Discovery-of-Electromagnetism-MS-PS/
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20 views

PARALLEL COMBINATION OF SUPERCONDUCTORS AND RESISTORS [duplicate]

........................please reply to the question above in the picture. I have tried a lot and have thought about it for a long time. Please help me and answer in simple words. AND I REQUEST NOT ...
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1answer
52 views

Power generation with a long, horizontal pipe, using atmospheric pressure differences

Straight to the point. If I float a pipe starting from a point in the ocean that has the atmospheric pressure of 101 kPa (Call it Point A) all the way to another geographic position on the ocean with ...
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0answers
30 views

Dynamic energy of capacitors in circuit

If I have 3 capacitors and 1 battery in a circuit how should I connect them in order to have maximum dynamic energy, when I connect them with the battery? Parallel or in series?
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1answer
29 views

Electric field inside an insulator's cavity [closed]

I'm trying to find the electric field inside insulating sphere's cavity, and I don't know how. However, if there was an conductor I'd know that $E=0$ from Gauss's Law.
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0answers
10 views

Charges on outer faces of parallel plate capcitor

Can there be charges on outer charges of a parallel plate capacitor if both the plates are initially charged by different amount and then connected with a battery.
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1answer
28 views

Electricity Transformers and power

Since Power = V*I increasing voltage reduces current and so it is better to have a higher voltage. My question is, since voltage is potential difference i.e. joules per metre, increasing the voltage ...
25
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7answers
3k views

Why are the electric force and magnetic force classified as electromagnetism?

I confuse the four kinds of fundamental interactions, so I think the electric force and magnetic force should not be classified as a big class called electromagnetism. Here is my evidence: The ...
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0answers
69 views

Finding the stored potential energy in a uniformly charged solid sphere

my question is finding the energy stored in a charged solid sphere. I believe I have the correct answer with: E=(4π/3)ρR^3 A uniformly charged solid sphere has a charge density ρ and radius R. Find ...
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2answers
65 views

Electrocuted at Parking Pay Station After Snorkeling [closed]

This is my first time posting here so bear with me. Also, the circumstances are strange so I am posting quite a bit of detail because I don't know what is relevant and what is not. The short story is ...
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1answer
40 views

Why is the average thermal velocity 0?

Thermal velocity is the velocity of the free electron due to their random motion. So how is the average value 0?
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1answer
18 views

Difference between energy loss at high voltage and high current

When reading about power transmission one very common statement is that power is transmitted at high voltage to minimize loss in the form of heat. What confuses me is the governing equation. Aren't ...
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1answer
30 views

Resistivity - Resistance of a wire wounded closely together

Here is the question I'm facing, The cross sectional area of a bare wire is a square of area 1.00mm^2. A 10.0m, length of this wire is wound close together on a wooden cylinder so that neighbouring ...
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0answers
32 views

Why both fuse and earthing ???' [migrated]

This question arose in my mind today that when you already have the fuse for safety precautions why do you need the earthing?
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1answer
69 views

No photoelectron is emitted from which of the following metals?

So there was this multiple choice question in an exercise in a bookI'm reading. I know that the forum is about discussions. But I want to know what the answer to the question is and why it is so. ...
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0answers
19 views

May the total charge in a supercapacitor be different using unipolar and bipolar voltage power supply?

Consider a supercapacitor where a Helmoltz double layer is formed at each of the 2 electrodes, which is like having 2 capacitors mounted in series, but with different polarities. The total charge at ...
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2answers
68 views

Which part of my idea is wrong about infinite energy produced by EMF for certain circumstance?

As a someone who is on the first year of EEE student, facts in a simple way: time varying magnetic fields around conductors produce electricity for outer space, object will keep going at the same ...
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0answers
17 views

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
758 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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0answers
21 views

Doubts wrt Electromotive force

The definition of emf states that when a cell is in open circuit , the potential difference between the terminals of the cell is called the emf. Now i dont understand that how can p.d. be taken into ...
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2answers
37 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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0answers
22 views

Two charged conducting spheres when placed in contact with each other [duplicate]

What happens when two charged conducting spheres of different radii are brought in contact with each other. How does it affect the charge distribution and field lines of spheres?
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1answer
50 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
40 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 ...
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0answers
59 views

Why does it matter which way I put a battery into an electronic device? [migrated]

If I take a battery, some wire, and a light bulb and hook them all in a circuit that would create a current and light the bulb. If I turned the battery around so the terminals were switched then I ...
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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
68 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 ...
0
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1answer
36 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
36 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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0answers
22 views

Power formulas? [duplicate]

Are different power formulas in circuits used for different reasons? For Example Power = V^2/R Power = I^2/R Power = VI
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2answers
37 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, ...
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1answer
78 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
384 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 ...
3
votes
2answers
71 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
91 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
99 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 ...
14
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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
57 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
votes
1answer
26 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 ?
0
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1answer
49 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 ...
0
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1answer
19 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 ...
0
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1answer
16 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
39 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 ...
0
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3answers
115 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
97 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 ...