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# Tag Info

## New answers tagged electric-circuits

1 vote

• 3,112
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### 3 Aspects of Voltage that contradict each other

Perhaps the best mental picture for voltage is elevation. Taking Gravitational Potential Energy $E_g= mgh$ divided by the mass, gives us Gravitational Potential: $$V_g= \frac {E_g}{m} = gh$$ And since ...
• 10.1k
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### 3 Aspects of Voltage that contradict each other

(Electric) potential energy $U$ is associated with a charge $q$ and its location in an electric system. (Electric) potential $V=U/q$ is (electric) potential energy per charge, a measure that makes it ...
• 51.7k
5 votes

### 3 Aspects of Voltage that contradict each other

1- Voltage is Potential Difference: Voltage is the difference between the energy levels. The potential difference between two points is the work required per unit charge to move the charge between ...
• 75.7k
7 votes
Accepted

### 3 Aspects of Voltage that contradict each other

Basically the problem here is using the same words for similar and related concepts that are nonetheless not identical. The fundamental concept that is behind "voltage" is the concept of ...
• 2,367
1 vote

### Why doesn't an EMF source directly affect the internal charges in a wire, but only the surface charges

In steady state, in a uniform conductor, the charge density within the body of the conductor is $0$. All net charge lies on the surface(s) of that conductor. Proof: In steady state, all derivatives ...
• 3,112
0 votes

### Why doesn't an EMF source directly affect the internal charges in a wire, but only the surface charges

does the battery field only affect surface charges, or both surface and inner charges. In stationary regime, inside a uniform conductor, whether the current is zero or not, net charge density ...
• 39.6k
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### Are $U^2/R$ and $I^2*R$ the same?

The correct formula is $P=IV$. Here is a simple argument to understand this, based on Newtonian mechanics: The power dissipated by an electron moving with velocity $v$ under action of force $F=eE$ is:...
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3 votes
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### Are $U^2/R$ and $I^2*R$ the same?

You made a mistake in using the formula. In that formula, U is not the transmission voltage, but the potential difference across the electric line. Even though we usually transmit at 220kV, that ...
• 428
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### How do circuits work at a subatomic level?

The voltage of a circuit is determined by the potential difference of the source. If I take a 4.5V battery and short-circuit it, then theoretically (neglecting the internal resistance of the source ...
• 10.6k
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### Can the speed of light inhibit the synchronisation of a power grid?

A related problem is instability. I don't think the current means to control synchronization issues using dynamic reactive compensators (as mentioned above) is going to be good enough when there are a ...
4 votes
Accepted

### The work-energy theorem in a resistor

The work energy theorem states that the net work done on an object equals its change in kinetic energy. Note my emphasis on net. The reason the kinetic energy does not increase is the resistance does ...
• 75.7k
5 votes

### How do circuits work at a subatomic level?

Circuits do not work at the subatomic level. Circuits are an approximation to an approximation of what happens at the subatomic level. Electromagnetism at the subatomic level is governed by quantum ...
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1 vote

### How do circuits work at a subatomic level?

Since these resistors resist the flow of charge, therefore, they take in some of that original push. Now it seems as if since the electrons in the resistor can’t move as freely, the current decreases.....
• 75.7k
2 votes

### Coaxial cable and faraday cage: why those shielding properties precisely?

But is it still true in the context of wave propagation? Yes, a coaxial cable still has its shielding effect during wave propagation. If I assume I send a current pulse on the outer shield, will it ...
• 131
26 votes

### Can the speed of light inhibit the synchronisation of a power grid?

You are correct, so what does the industry do? Grid Design and Control: Power grids are engineered to account for phase differences and signal propagation times. They use various devices, such as ...
• 487
11 votes

### Can the speed of light inhibit the synchronisation of a power grid?

Even worse than that - any piece of wire has its own inductance and capacitance, which are non-negligible when the line is long. Essentially, a power line acts as a waveguide, which sustains its own ...
• 61.8k
1 vote

### Arduino -> bulb brightness

If you trace the wires in your actual circuit (not your drawing of a circuit which is different) you see it's two resistors in parallel, then that combination is in series with a LED. In a circuit ...
• 1,537
2 votes

### Assistance Needed to Identify PhD Advisor of Herbert Joseph Reich

Although this may be the wrong place to ask your question, this may provide the answer to your question: Frederick Bedell (Cornell) according to https://academictree.org/etree/tree.php?pid=871990 I ...
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### Arduino -> bulb brightness

EDIT. The original answer was meant to deal with incandescent bulb lights The electric circuit you have graphically represented is not the same as your "physical" circuit: the physical ...
• 10.8k
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### Doubt in Potentiometre Resistance

The circuit you are investigating is shown below and you are going to compare potential differences across the battery, ie across nodes $A$ and $B$, $V_{\rm AB}= \dfrac{\mathcal E \,R}{r+R}$. The ...
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0 votes
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### Doubt in Potentiometre Resistance

if we connect an external resistance in parallel to the cell, then why is resistance added like seris while calculating the current flowing through the cell and resistance ? The confusing aspect (...
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1 vote
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### What is the difference between turns and layers in winding?

Imagine you are winding a coil onto a cylindrical bobbin. your winding machine "lays" the wire down as you go and for every complete turn of the bobbin, it advances the wire spool by one ...
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### Voltage drop in a forward biased diode

I'm trying to understand why is there a voltage drop when a diode is in a forward bias. Here is an image of the electric potential between and around the plates of a capacitor. (image modified from ...
• 3,112
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### Stating Kirchhoff's Voltage Law

But is it correct to state the law as the algebraic sum of the voltage rises equals to the algebraic sum of the voltage drops in a closed loop? Yes. Kirchhoff actually stated the law as the sum of ...
• 3,112
1 vote

### Mirror symmetry in circuits

Remove heater A. In terms of a vertical line through the centre the resistors and heater on the left side of that line are arranged in the same way as the resistors and heater on the right side of the ...
• 98.6k
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### Why are electrons in a wire so slow and what exactly makes them move?

Imagine you have a narrow circular trough (like a moat), and to make visualization easier, imagine it's filled with a line of ping-pong balls instead of water. You push one of the balls a short ...
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