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Questions tagged [electricity]

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

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Charging a battery

So we have a charger outputting V volts and $I$ Amperes and two rechargable batteries of the same capacity $Q$ coulombs but different emf's $V_1\&V_2$. Which battery would charge faster? ...
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35 views

Does duration affect how lethal a current is?

It's been said in many places that it's not voltage that kills you but the source's current (or more so a combination of the two), but take a current of 0.1A which can be considered fatal. Would a 0....
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2answers
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Confusion on AC in LIVE & NEUTRAL WIRE

So if an AC current means the elctrons are alternating or changing direction in a given time, how does this apply to live & neutral wire, don't they flow in one direction only? Please answer it as ...
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1answer
32 views

Why is the current through this ammeter 0A?

I have the above circuit, and the current through the ammeter is 0A. But why is this the case? Is there any way I can easily show that the potential difference across that segment is 0V? Also, the ...
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1answer
30 views

Why does a fuse trip when plugging in $N$ chargers simultaneously?

Scenario 20 computer chargers, say, are plugged into extension cords of 5 outlets each, and those extension cords plugged into fifth. There is no mechanism for "soft-charging". The chargers are ...
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16 views

Switch spark suppression [on hold]

Maybe you can help me with the following question: The circuit attached is a simple, steady state DC current with a resistance R. C1 is a conductor with a few times larger area than conductor C2. How ...
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1answer
21 views

Do solar panels generate more electricity at higher altitudes?

The atmosphere is thinner at higher altitudes, so do solar panels get more energy from the sun? Does the cold help or hinder their performance? Is a solar panel in space with no atmosphere is the ...
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1answer
25 views

Fire-powered thrusters? [on hold]

So recently I have been working on a science project for ideas that could possibly help in space expeditions, and one of my ideas would be a rocket that would be powered by flame, anyone here have an ...
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1answer
28 views

storing solar energy to potential kinetic energy [on hold]

I saw a post I could not join (no reputation), but my question is this: Why not use peak hours of solar or wind to store in kinetic energy, in the form of either water reservoirs -- or even elevating ...
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1answer
31 views

When DC current flows through salty water, how does the current flow? How can you tune the (narowness of) the path?

Consider this very simple and well-known experiment with dirty/salty water: The light bulb turns on, and current is flowing. How can you know how this current is exactly flowing, and how the electric ...
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1answer
42 views

How can I detect an electric field?

I can easily detect the presence of magnetic field over a surface by using compass or by placing some iron filings. But how could we similarly detect electric field over a place?
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2answers
32 views

Velocity factor in coax cables

I mainly see the term "velocity factor" used when referring to the velocity of propagation of an electromagnetic wave front in coax cables. This velocity seems strongly dependent on the properties of ...
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1answer
22 views

The effect of the resistance of coils on DC motor

I have some doubts on how the resistance of coil affects the efficiency of a DC motor. I assume there are two DC motors operating under the same supplied voltage, and the resistance of the coil $R_1$ ...
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1answer
18 views

Charge transfer from electrode to water

This is something that's bugging me for a while. Water is conductive because it has ions in it, which move to form a current. But how is the charge transferred from a electrode into the water, and ...
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2answers
44 views

A battery generates current according to the resistances within a circuit(V=IR)

A battery generates current according to the resistances within a circuit(V=IR).The charged particles enter and exit the source with the same magnitude, however, since we have said that the current is ...
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4answers
43 views

Is there a physical explanation for why increasing a capacitor's capacitance and the circuit's resistance decrease the capacitor's rate of discharge?

The voltage across a capacitor as a function of time is given by: V=Vi(e-t/RC) Therefore, increasing the resistance and capacitance increases the time it takes for the initial voltage to drop to e.g....
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2answers
398 views

Why doesn't using more appliances at home decrease the electricity bill? [closed]

I know that at home the electric circuits are parallel, and this explains why if one appliance (eg bulb) fails, everything else continues to work, but if more devices are added in parallel to each ...
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4answers
86 views

Is the vacuum permittivity a result of defining other units first?

From Coulomb's law $$F=\frac{1}{4\pi\epsilon_0}\frac{q_1q_2}{r^2}$$ If instead we defined the charge of a coulomb to be $\sqrt{\epsilon_0}$ times it is now, the force would be exactly the ...
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1answer
21 views

Electrically charging objects with a battery?

hi this is a weird question but is it possible to positively or negatively (or both) charge an object with a battery? I need to do it with a battery for a project and i have seen designs but i really ...
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0answers
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What happens in an electrochemical cell?

Suppose i have to make an electrochemical cell. I dipped the electrodes in electrolytic solution. Then after that what happens? Everyone knows spontaneous chemical reaction causes potential ...
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0answers
16 views

Power Dissipation in Internal Resistance of a cell in a circuit with varying resistance

In the circuit , the battery has an e.m.f. of 3.00V and an internal resistance r. R is a variable resistor. The resistance of the ammeter is negligible and the voltmeter has an infinite resistance. ...
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1answer
24 views

Pressure increment in a room due arc flash

If a short circuit occurs in an air-insulated electical switchgear, there might ignite an arc flash. The enrgy of an arc flash depends on several things, but there are many calculators for determining ...
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2answers
37 views

What is the physical significance of Dipole moment?

What does dipole moment physically signify? I know it is the product of 2 charges and distance between them. Like momentum is the product of mass and velocity, but physically it shows the quantity of ...
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1answer
36 views

How can only 2 phases of a 3 phase power system be used to power a load?

When looking at 2 of the 3 phases on a graph, there's a point where they're both positive or both negative. How does one of the phases act as a return path?
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3answers
36 views

Can a lightning which doesnt make light be made?

I was wondering if there is a way to make a lightning (lab lightning, nothing as chaotic as the real thing) that doesnt eject any electromagnetic waves? For example: How would a strong negative magnet ...
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1answer
25 views

Magnetic Dipole from 'Current' in LC Circuit

We can work out the 'current' in an LC (series) circuit by creating and solving an ODE: $$I\frac{1}{LC}+\ddot{I}=0$$ This provides us with a sinusoidal resonant response to any initial current. ...
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1answer
51 views

Would the shuttling ball experiment still work if the ball was grounded?

In the following video, the positive and negative terminals of a high voltage source are connected to two slightly separated metal plates. In-between the plates is a ball coated in conductive paint ...
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2answers
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How do $H_2$ lamps work?

When a hydrogen ($H_2$) lamp is subject to a high voltage hydrogen atoms release energy in the form of light. Somehow $H_2$ is splitted. But... Why high voltage produce the dissociation? Does ...
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0answers
47 views

Charge and its relationship to Voltage

I was working on a model to describe the voltage between two metal plates (like in a battery) and came up with this model. I wanted to see if my physics and math were right. So I started out assuming ...
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1answer
52 views

Creation of electric field inside a conductor

My book says that as soon as the two ends of a conducting wire touches the two terminals of a battery, it generates an electric field inside the conductor. Why?
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1answer
44 views

Calculating average value of a signal

The formula is $$ \frac{1}{T}\int_{a}^{b}S(t) .dt $$ I understand how the integral gives us the area under the curve, but average means the sum of all over how much all is, the integral here is the ...
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1answer
35 views

Is it possible to generate conditions such that the temperature difference created by current is high enough to sustain it?

We know that current can generate temperature difference and vice-versa. But is it possible to generate such conditions that the temperature difference created by current is high enough to sustain it?...
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4answers
454 views

Since water boils at room temperature in a near vacuum, is it possible to use this to generate electricity in some way?

This may be a blatantly obvious question but I've never heard about such a thing happening. Could this be possible in some way using a vacuum chamber to boil the water and spin a turbine?
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4answers
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Do electrons have a size or mass? [closed]

Do electrons have any size if not then how do they collide with positive fixed in in wires?
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2answers
47 views

Why does current from a grounded electrical outlet flow through me if I stay on the floor made out of a dielectric material?

Why does current from a grounded electrical outlet flow through me when I touch a "hot" terminal, if stay on the floor made of a dielectric material? Consider an AC voltage source, such as a wall ...
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1answer
51 views

If I, being in the jump, touch the socket terminal with 220 potential relative to ground it will not hurt me?

If a person jumps and then touches an electrical outlet's hot terminal at $220 \, \mathrm{V} ,$ would it cause them harm? Would any current flow through them? If a person on the 11th floor of a tall ...
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1answer
35 views

Conversion of electrical energy to heat in a circuit [duplicate]

How is electrical energy converted to heat in a circuit? I read on quora and other sites that it is due to how much resistance it receives due to colliding with atoms. However what exactly does it ...
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1answer
42 views

Electric potential at ONE point around an infinite line charge

The problem states that you've got two infinite charged wires with linear densities of charge (l and -l) and you must calculate the electric potential at any given point. I dont know how to do this ...
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3answers
52 views

Dependance of resistance on cross sectional area

I was wondering about a possibility......what if we take two conducting wires of the same material and the same length; both will have the same value of cross sectional area but one will be a hollow ...
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0answers
27 views

Flux Generated by Rotating Charge

If we push a charge into a uniform magnetic field, and the direction of the charge is perpendicular to the direction of the magnetic field lines, then the charge will rotate in the magnetic field. ...
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Could the tether of a space elevator be used as a single-wire transmission line?

If you're unfamiliar with single-wire transmission lines: https://en.wikipedia.org/wiki/Single-wire_transmission_line It seems that a material with high conductivity (eg: certain configurations of ...
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1answer
44 views

Underground river of lightning?

This question has been asked before but not the same way. A generator uses a magnet to push electrons down a wire to my house and turn on my light. Then those electrons take the expressway back to the ...
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1answer
50 views

Violation of KVL ,KCL at high Frequencies

question: How can we prove mathematically that KVL (Kirchoff's volatage law) and KCL (Kirchoff current law) become invalid at very large frequencies? i have read this statement in my book but it ...
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1answer
24 views

Potential difference between two points

Okay so this might sound kinda stupid but I'm new to electrostatics and I was doing a question that asked me to find the potential difference between two points . Now I calculated the potential at the ...
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1answer
34 views

Will a magnetic field damage a laptop charging brick? [closed]

I recently got a Dell laptop for school. It has a charger, like the one below. Being the good student that I am, I applied my knowledge about electricity flowing in a loop and began wondering if I ...
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1answer
61 views

Can I trap mosquitos with Coulomb's force? [closed]

Can I fill a metallic conductor with a very large positive charge, attach it with a insulator to a wall, put it near a window under the sun (visible light and UV in order to cause it to expell ...
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1answer
38 views

derivative of the electric field along the normal to the surface near the conductor

how to derive the formula approves the derivative of the electric field along the normal to the surface near the conductor is inversely proportional to the principal radii of curvature? $\frac{\...
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2answers
35 views

Derivation of the formula for Electric Potential Energy

I just learnt the formula for calculating Electric Potential Energy $W=\frac{1}{C}\int_0^Qqdq = \frac{1}{C}[\frac{1}{2}q^2]_0^Q=\frac{Q^2}{2C}$ I understand the methodology, but what I do not ...
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1answer
48 views

Magnetic field through walls

Is it possible to measure magnetic field from a household ac (50Hz) conductor inside a wall?
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1answer
42 views

Magnetic Turning Wheel [duplicate]

So a few years ago I came up with the idea of a magneticly powered wheel that could be attached to a generator and power it, it would not be infinite as over time magnets lose their power yet I think ...