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

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10k views

Why does the current stay the same in a circuit?

I was informed that in a circuit, the current will stay the same, and this is why the lightbulbs will light up (because in order for the current to stay the same, the drift speed of the electrons need ...
0
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1answer
38 views

Why does the primary coil get very warm with DC supply but not with ac supply?

It's about an investigation carried out on the transformer effect . The primary coil of 20 turns and the secondary coil of 50 turns is wound around a laminated iron core.
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2answers
46 views

Uniformly charged rod electric field

A uniformly charged rod of length $L$ and total charge $Q$ lies along the $x$ axis as shown in in the figure. (Use the following as necessary: $Q$, $L$, $d$, and $k_e$.) (a) Find the components of ...
4
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3answers
3k views

General integral to find resistance

My question is: is there a simple and truly general equation for the resistance between two electrical equipotential surfaces?. Obviously, if so, what is it, and if not, why? It would be very ...
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2answers
293 views

Electricity Flow and Ground Wire

Pre-face: My step-father and I were turning the heat down on the water heater. He demonstrated that touching the ground wire doesn't shock you. My understanding is that the ground wire doesn't have ...
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4answers
2k views

Why Change Of Magnetic Flux Induces Current In circuit?

Why change of magnetic flux with the time through a coil induces current in it? Please tell me that what happen to charge in the coil if the magnet or electromagnet wave around this? Also, why a ...
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1answer
3k views

What is an ohmic conductor?

Is it a conductor whose temperature doesn't change when you increase the current through it, or a conductor whose resistance is constant provided its temperature doesn't change? I've seen it defined ...
3
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3answers
87 views

when current passes through a wire , does it only travel through the outer surface?

In electrostatics we are taught that the field inside a conductor is always zero . So when current passes through a wire , the electricity only passes through the surface of the conductor . In ...
4
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1answer
2k views

The possibility of free electrical energy?

Please excuse my lack of knowledge/understanding. Question: Why Nikola Tesla's Free Energy concept was never worked upon? Even today. Context: Now that we know Nikola Tesla was a genius and did ...
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1answer
33 views

What will happen if we establish a physical connection between ground and ionosphere?

https://en.wikipedia.org/wiki/Ionosphere The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km (31 mi) ...
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0answers
31 views

How does the velocity of a magnet falling through a solenoid affect the induced voltage?

Given Faraday's Law, $\mathcal{E}=-N \frac{\partial \phi}{\partial t}$, we can induce an EMF by dropping a magnet through a coil of wire. How would the velocity of this magnet relate to the induced ...
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2answers
1k views

Can a battery charger be too powerful for a rechargeable battery?

I got the impression that a regular iPhone charger can charge the iPhone and the iPhone won't become too hot while charging, and the charging time is standard, but if using the 10W iPad charger to ...
4
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1answer
62 views

Do any fundamental particles with gravitational or electric dipoles exist?

For magnetism: $$ \oint \vec{B} \cdot \mathrm{d} A = 0 $$ For electricity: $$ \oint \vec{E} \cdot \mathrm{d} A = \frac{Q}{\epsilon_0} $$ For gravity: $$ \oint \vec{g} \cdot \mathrm{d} A = -4\pi G ...
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1answer
325 views

Where do the electrons go?

In our house most of the plug-points have 2 holes. I know that one hole is neutral and other one supplies electricity. I can say that when i plug any device and turn the switch on electricity starts ...
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5answers
14k views

Relation between Power, Voltage and Current when one or more of them is amplified?

$$\text{Power}(P) = \text{Voltage}(V) \cdot \text{Current}(I)$$ If voltage or current is amplified or multiplied what happens to power and current. Does this affect in increase or decrease in power ...
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2answers
33 views

Why is it that for a source of emf, current flows from lower to higher potential?

I'm quite confused about this actually! In fact, I had always thought current flows from a region of higher potential to a lower one. Does it have anything to do with the fact that it's a source of ...
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1answer
76 views

Electrolysis of copper sulphate solution using platinum electrode [closed]

Please explain the electrolysis of copper sulphate solution using platinum electrodes ,and explain why copper ion was preferencially discharged rather than hydrogen ion,and also were the hydrogen came ...
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3answers
26 views

Difference in directions of charge and current.?

I just dont understand that why does charge flow in a different direction as that if current when current is the rate of flow of charge.
2
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1answer
230 views

Is electric current a scalar quantity?

According to the definition of a Scalar quantity that i have read in class 9 is that ''those quantities which has only magnitude but no direction is known as a scalar quantity''.....But in class 10 i ...
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2answers
42 views

What is permittivity in free space?

From Coulomb's law, we know that epsilon-not means permittivity in free space. It's unit is C^2 N^-1 M^-2 ( coulomb sqr per newton per sqr meter). But what does it mean PHYSICALLY? For example, 1 Pa ...
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1answer
41 views

How does voltage produce current?

I am studying electric current and i dont understand how does voltage(potential difference )produce current? PS : I am a 10th grade student so please avoid complicated terminologies.
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2answers
2k views

What makes Human a Conductor

Conductors, are those which have free electrons... and because of this have same electric potential all over. But considering our body, which has many electrical voltage, current signals passing by in ...
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4answers
2k views

Ohm's law holds at constant temperature - what about Joule heating?

Ohm's law states that the resistance of a conductor is constant provided its physical conditions, such as temperature, remain constant. But what I'm thinking is that as you increase the voltage across ...
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5answers
272 views

The measurement of electricity

I'm a student trying to understand electricity. As I learned from school, electricity is the flow of electrons, but I'm confused about the measurement of electricity. As I learned, voltage is the "...
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3answers
607 views

Will Positron Cause flow of electricity?

Recently someone told me about antimatter. Antimatter is something that is completely opposite to matter. What I would like to know is let's say this universe was made of Anti-Matter. So since the ...
0
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2answers
37 views

Why does electromagnetic induction creates both voltage and current but static electricity only creates voltage and no current?

Why is it that electrons do not move the same way in triboelectric as in magnetic induction when both creates voltage? Triboelectricity can even create tens of thousands of volts like Van De Graf ...
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2answers
21 views

Electricity and electric fields equations [closed]

Whats the difference or relationship of $q$ between the equations $E=F/q$, $v=W/Q$ and $Q =ne$ ?
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1answer
7k views

Why does pushing a magnet inside a solenoid produce current?

If you push a bar magnet inside a solenoid, a current is produced. But why is that? I mean, the wire is being moved along the magnetic field, so taking the cross product: $\vec{F} = I\vec{V}\times\...
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1answer
25 views

Current flow in absence of a potential difference [closed]

What if at two different points in a wire connected to a system of capacitors and resistors, the electric potential is equal. Will the current flow? There is also a battery connected.
0
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1answer
23 views

Induced current in a rectangular loop [closed]

The question is How much heat is generated in the resistor during the loop's entire path into and out of the magnetic field? Give your answer in J. I used Faraday's law and managed to get the ...
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1answer
33 views

Wind turbine impact on cars fuel consumption [closed]

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? ...
0
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3answers
55 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 ...
0
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4answers
254 views

Transformers and DC voltage

Ok, if I have a transformer with 100 coils of the primary and 200 coils on the secondary and I connect a 9 volt battery to the primary, how many volts should I expect from the secondary coil? I know ...
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1answer
64 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
33 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?
27
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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 ...
0
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1answer
42 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
14 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.
0
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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 ...
0
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1answer
28 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 $...
9
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4answers
22k views

Can the Earth's magnetic field be used to generate electricity?

Since the Earth has a magnetic field, can it, in theory, be run through a conductive metal coil to create electricity?
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3answers
789 views

How to find the distribution of charge on two spheres connected by a conducting wire?

A solid metal sphere of radius $R$ has charge $+2Q$. A hollow spherical shell of radius $3R$, concentric with the first sphere, has net charge $-Q$. What would be the final distribution of the charge ...
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2answers
67 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 ...
0
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1answer
57 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?
0
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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 ...
1
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1answer
47 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 ...
0
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2answers
137 views

The source and sink phenomenological description of charge - how realistic is it?

I've heard over and over an electron described as a source of the electric field, but that is a misleading term. Source makes one thing of a tap, with a constant flow of something coming out of it. ...
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1answer
79 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. ...
0
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0answers
24 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
4k views

Calculating the energy supplied by a battery

If you wanted to calculate the energy supplied by a battery in time $t$ you would use $E=VIt$ where $I$ is the current through the battery. If the internal resistance is $r$ we could also use $E=\frac{...