A measure of the rate at which electric charge is transported (especially through a circuit), it has units of charge/time.

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21 views

How is ampere defined for alternating current?

Both alternating current and direct current are measured in ampere. But how is ampere defined for alternating current? It cannot be defined from two mutual attraction of two parallel wires carrying ac ...
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0answers
6 views

debris removal by electrification

Often during the lifetime of equipment, there is debris or residue accumulation on surface of, for example nozzles. This material accumulation can be quite strong. What kind of forces are they ...
-3
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3answers
84 views

Why the shunt resistor would not protect the ammeter when the ammeter connected in parallel?

when you connect the ammeter in parallel it will burn or damage the ammeter. My question is, why the shunt resistor in the ammeter would not protect the ammeter when the ammeter connected in parallel. ...
-1
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0answers
20 views

Current flow between two batteries

If we connect a bulb or led between a +ve terminal of one cell and -ve terminal of the other, and leave the other terminals of the cells unconnected, will the bulb or led glow? Will it glow if we ...
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1answer
36 views

Electromagnetic radiation from AC circuit?

Is it possible that an AC circuit emit electromagnetic radiation? I have read somewhere that due to change in polarity of the current continuously, electron oscillates in SHM at a mean position. ...
0
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0answers
11 views

Change in magnetic field region reduces overall voltage due to change in resistance?

Consider the following diagrams: Diagram(1): A large conductive slab($C$) with resistance ($R$) and region with magnetic field($B$), the conductor moves to the right as indicated with ($v$). ...
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1answer
40 views

relationship between voltage and current

I know that this question had been asked many times but I think it will be a new info in Ohm’s law: $$R = V/I$$ So Voltage is directly proportional to Current In Electric Power’s law: $$P = ...
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0answers
20 views

Does the voltage of a spark depend on length and thickness of a spark across a gap? [closed]

Can the voltage that creates a spark be estimated by the length and thickness of the ark it creates across a gap? I made a zvs flyback driver with 2 IRFP250 MOSFET transistors running from 2.5 Amps ...
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0answers
10 views

What is the role of the Cowling, Pedersen and Hall resistivities (or conductivities) in plasma physics?

The current density $\vec{j}$ can be computed as $\vec{j} = \vec{\vec{\sigma}} \vec{E}$, where $\vec{\vec{\sigma}}$ is the conductivity tensor and $\vec{E}$ is the electric field. This conductivity ...
2
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2answers
67 views

Showing that the magnetic field inside an infinite current carrying cylinder is zero

I'm doing some self studying of introductory physics, and was working a question from a textbook that has several parts. The first few parts asked me to show that the magnetic field of an infinite ...
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0answers
17 views

Voltmeter across two loops

If one terminal of a voltmeter is connected to a closed loop with current and the other to an open loop, will there be a reading? Theoretically, there is a potential difference across the terminals, ...
0
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0answers
40 views

Finding the magnetic field due to a current carrying field at a point within the circumference

This is a question me and my friend were wondering about. How can one calculate the magnetic field due to a current carrying loop at a point in the area enclosed by the loop. For example, at point P ...
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2answers
18 views

Time constant for this RC circuit

Well one problem boiled down to the following RC ciruit- $C_1$ was initially charged with $q_o$ and I thought after closing switch connecting $C_1$ and $C_2$ the maximum current discharging will be ...
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1answer
47 views

Two Current Carrying Loops: Multiple Choice Question

I'm studying some simple multiple choice questions from an old test in electrostatics and I have some trouble intuitively grasping this question. I hope someone can explain the solution! Two current ...
1
vote
1answer
26 views

Why does the axle need to be rotated in a turbine generator?

Inside a turbine a wire rotates between the poles of a magnet, i.e. rotating inside the magnetic field, so that the field forces the electrons in the wire to move and generate current. But why does ...
2
votes
1answer
36 views

Electron Flow Notion

I would like to ask something that bothers me. A lot of us know of the electron flow notion, which it is the technical representation of how the electron charge really flows, starting from the ...
0
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1answer
35 views

Which power equation to use: P = (I^2) * R or P = V^2 / R

Ideal max voltage V = 200V and max current I = 5A (these are both given) Therefore ideal resistance R = V/I = 200 /5 = 40 ohms Therefore Ideal max power P=IV = 5 * 200 = 1000W 1st power equation: P = ...
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votes
3answers
40 views

About the flow of current

Generally it is said that current is due to the flow of electrons; how can we make this claim? I mean, generally we say the atom contains a nucleus which consists protons (positively charged ...
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2answers
55 views

How can be the neutral wire at 0 volts when current flowing through it?

Voltage is potential difference, and current flows because of voltage. So if the voltage is zero, how can current flow through the neutral wire.
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1answer
42 views

Eddy Currents – Tubes with slits

When a magnet falls down a tube, eddy currents form and flow around the tube, perpendicular to the direction in which the magnet falls. However, when there is a vertical slit in the tube, are ...
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0answers
21 views

Current flow direction, based off the equipotential line?

From the following diagram: Given the wires are only connected to a certain portion of the conductor, will current flow all around the conductor? Or only throughout the equipotential line(diagram ...
0
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1answer
19 views

Does doping and size determine the characteristics of a semi-conductor?

Does the maximum voltage and current that a semiconductor can withstand (without being damaged) depend upon the size and doping of the semiconductor? If so, then please explain, 1.What is the reason ...
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votes
2answers
60 views

Rate of flow of electrons in a simple circuit, given the current? [closed]

I have this question: The correct answer is C. I understand that the flow of electrons should be from Y to X because electrons flow opposite to "conventional current", which is from positive to ...
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1answer
98 views

Difference in induced current, when magnetic field “span” is reduced?

A conductor of known volume $(V)$ passes a uniform magnetic field$(B)$with a constant velocity $(v)$ the conductor is a source of induced EMF, a power source to a circuit. The induced EMF can be ...
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1answer
38 views

Spin-resolved current [closed]

What is spin-revolved current? Is it the spin current?
0
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1answer
51 views

Current Electricity

If $$ \frac{dQ}{dt} = I $$ and if an accelerated current produces E.M. waves (radiation), does that mean $d^2Q/dt^2$ (second derivative of a charge w.r.t. time) will give me the magnitude of the wave ...
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1answer
49 views

What happens if I have a square conducting wire being permeated by a magnetic field and the field suddenly disappears?

Suppose there is a square conducting wire in a magnetic field. The two vertical branches will have the same emf, and the two horizontal branches will have 0 emf, resulting in a net emf of zero and ...
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1answer
32 views

How does a bulb light up when it's connected in a circuit with an uncharged capacitor and a cell?

Since there is a capacitor, isn't it an incomplete circuit? How does the current flow across the dielectric medium? If a bulb was connected to a cell alone and if there was a break in the wires of the ...
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1answer
43 views

Can electromagnets repel?

So I saw a video here https://www.youtube.com/watch?v=wzXRFp0DDrU (See the full video first) I don't understand that how is the electromagnet repelling things in the second half of the video? Also ...
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0answers
15 views

Show that the electric dipole term vanishes for a particular current

I'm interested to show that given a ring with radius a where there's a current $I_0 \cos \omega t$ ($I_0$ is a constant) there is no radiation due to the electric dipole term (appearing in the ...
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0answers
13 views

Current pass through different branch of network [duplicate]

How current knows that resistance in any branch of network is law show that more proportion of it pass through that branch?
-1
votes
2answers
120 views

Electrical resistivity: the effect of adding electrons

Consider a copper wire of fixed length and cross-sectional area, and apply an electric field to the wire induced by a fixed potential difference $V$ across the two endpoints of the wire. By Ohm's law, ...
0
votes
4answers
115 views

How power lines use high voltages with a low current?

I've read that power lines use high voltages and low currents to reduce power loss due to resistance. Looking at the formula for power - P = VI So to increase P, you increase V rather than I for ...
2
votes
3answers
81 views

Proof for Resistance is directly proportional to length and inversely proportional to the area of cross-section?

I have heard that Resistance is directly proportional to length and inversely proportional to area of cross-section. Can someone give me a practical explanation for this?
8
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5answers
3k views

How can one derive the Ohm's Law?

I am looking for the derivation of the Ohm's Law i.e., V is directly proportional to I. Can someone help me with it?
3
votes
1answer
50 views

Would a solenoid move if a magnet went through it?

If you were to have a solenoid (0 current) floating still in space, and shot a magnet through it, would the solenoid move, or would it only create a DC current (what if it has a closed/open circuit)? ...
0
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0answers
32 views

Can current be stopped using magnetic field?

Is it possible to stop a current "running" through wire only by using a magnetic field around the wire?
1
vote
1answer
50 views

What is the defintion of a current-current diagram?

Right now I am facing some Feynman diagram calculations and in the instructions I am reading the phrase current-current diagram appears quite often so I wanted to know: What is the definition of a ...
0
votes
2answers
134 views

Induced EMF, additive to conductor's closed circuit?

Assume the following conductor, with current flowing, powered from a source $S$: Now, I've introduced a magnetic field($B) to the conductor covering a small area of it like so: The change in ...
0
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0answers
19 views

Why is Ampere not a derived SI unit? [duplicate]

From my understanding, Ampere is amount of elementary charge per time. So, you should be able to derive it from mol, which is amount, and seconds, which is time. My question: Why is Ampere a base ...
0
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0answers
37 views

Gravitomagnetic railgun

Would a gravitomagnetic analogue of a railgun work as expected, in theory? Consider replacing the electric currents on each rail with mass currents. Then place a mass between the rails, moving with ...
0
votes
1answer
101 views

Current on both sides of a capacitor

When a capacitor is connected to a DC circuit, what ensures that the current on both sides of the capacitor is the same? When charges arrive at one end of the capacitor they stop moving; presumably ...
1
vote
3answers
76 views

Why is $\nabla \cdot \vec{J} = 0$ where $J$ is the current density?

This is quoted from Purcell's Electricity & Magnetism: ...if charge forever pours out of, or into, a fixed volume, the charge density inside must grow infinite, unless some compensating charge ...
2
votes
3answers
49 views

Why is resistance across a load the V per I rather than the V per Q?

There is a load that resists the flow of electrons. This causes a voltage drop, meaning it creates a potential difference between the 2 sides of itself. This property, a load creating a voltage drop, ...
0
votes
1answer
39 views

Will the current flow from the battery?

I am just trying to find out if the current enters into the positive terminal of the battery (if there is a battery with bigger emf ) will it get charged and charge will be stored and current will ...
-3
votes
2answers
45 views

Doubt on resistor circuit [closed]

How are we able to flip the triangular resistor to the opposite breaking its connection with the lower 2r resistor?
0
votes
1answer
31 views

Is internal resistance relevant in motional EMF?

When a conductor passes a magnetic field and connected to a circuit, the induced voltage is calculated via the motional EMF($\epsilon$): $$\epsilon=-vBL$$ Is the conductor's resistance (or internal ...
0
votes
2answers
50 views

why in the case of electric field the path of electrons is curved? [closed]

I was wondering ,that why in the presence of uniform electric field the electrons are moving in a curved path.
0
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2answers
54 views

Why is voltage essential in circuits?

I understand what voltage is, but why is it necessary for an electric circuit to function? Why can't current flow without a voltage?
0
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1answer
40 views

Reducing eddy currents, changes the property of the conductor & circuit?

In an attempt of reducing the eddy currents in a conductor, such as having gaps to break the induced eddy currents, would that by any chance change the conductor's orientation from series to parallel? ...