Tagged Questions

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

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1answer
32 views

Why is electricity so successful (how to explain the variety of transducers we have discovered)

From piezoelectric crystals, to loudspeakers, microphones, hydrophones, strain gauges; electricity possesses the amazing ability to transfer energy/information to and from so many different media. I ...
0
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1answer
20 views

Solving kinetic energy exercise through electrical work formula instead of voltage formula?

While studying electric potential, I run into an issue on exercise 43 of Chapter 24 of Fundamentals of Physics 8th ed. Vol. 3 (Halliday et al.). The exercise states the following, paraphrased: A ...
-3
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0answers
24 views

What actually is Electrical Resonance? [on hold]

One series R-L-C circuit with parameters R1, L1, C1 is in parallel with another series R-L-C circuit with parameters R2, L2, C2. At what frequency of excitation of source which is purely sinosuidal, ...
4
votes
1answer
49 views

Distribution of current of a rotating cone

If I have a hollow cone (surface with no bottom cover ) as the one in the picture. The cone has surface charged density $\sigma$. It rotates around the symmetry axis with an angular velocity ...
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0answers
29 views

How to accurately mark with arrows an electric circuit

As I understood, we choose to mark the current with arrows going from the plus pole to the minus pole (even though we know that in reality it is the contrary). As I'm looking at electric circuits, I ...
4
votes
3answers
238 views

How is Kirchhoff's voltage law understood in the water flow analogy?

I met the Kirchhoff circuit laws in the past, but now I'm trying to associate them with a practical representation to be sure to understand them. Let's start with the Kirchhoff current law: If I say ...
0
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0answers
42 views

keyboard very strange behaviour [on hold]

I have a USB keyboard which has a somewhat faulty wire. On shaking the wire, the USB keyboard sometimes gets disconnected or sometimes gets connected. This is normal. But I have another very strange ...
0
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1answer
50 views

Does alternating current come from DC?

I wonder whether alternating current is produced from DC current or whether AC and DC are entirely different concepts. Is there any relationship between AC and DC?
2
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3answers
63 views

The Difference Between voltage and current

I know that this question has been asked many times before, and I have read over several of the threads asking this question, but they do not include the gripe I have with my problem of understanding ...
1
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0answers
31 views

Why are ammeters used in series and voltmeters in parallel?

As I'm reading a course on electricity, this one says that an ammeter should be branched inline and not on a bridge. Can someone explain to me physically why we branch a amperemeter inline and a ...
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0answers
9 views

writing node-voltage equations [on hold]

I tried at least four times but I can't solve the question. I don't know where my wrong is. Thank you for all appreciated answers. images:
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0answers
38 views

About the nature of the electric current

I'm currently studying electricity on my own, and as I read in a metal electrons are moving across the metal freely (depending on the attraction of the nucleus). As we close the circuit, an ...
0
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1answer
42 views

Why is the voltage negative?

What I don't understand is why the the two voltage sources are subtracted when working out the emf for part a, The graph does not show the orientation of the solar panel so I thought I was to ...
2
votes
3answers
49 views

Calculate the flux of a point charge with Gauss's law

I know from my class that to calculate the flux of a point charge with Gauss's law, I have to make a surface that intersects with all of the flux lines resulting from the charge, and then make this ...
0
votes
1answer
15 views

Electrical charge equilibrium and the piezoelectric effect

About the piezoelectric effect: if I press a crystal the electrical charges segregate and an electrical voltage appears on the other two faces of the crystal. See this link for example: ...
0
votes
2answers
43 views

Is there a relationship between the diameter of a copper wire and the bandwidth it can carry?

I'd suspect intuitively that the bandwidth should decrease as the diameter decreases, but I don't have any reasoning to back it up. Secondly, would the actual wavelengths that it can carry, also ...
0
votes
1answer
23 views

Transmission lines…which one is high? potential or potential difference?

The electric potential at generating station is 11,000 V...why such high potential is generated there? From generating station it is transferred to local station...is there any electric potential at ...
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2answers
32 views

Calculate expected Voltage at a distant electrode

Firstly, please forgive me for misconceptions and errors as my knowledge of Physics is very basic. I have EEG data (uV vs time) traces for an array of platinum electrodes placed on the surface of ...
0
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0answers
58 views

Is ohm's law violated in electric transmission lines?

Electricity is generated at a very high voltage say, 11,000 V... Does that voltage refer to the potential difference across the transmission line or does it refer to the electric potential at the ...
0
votes
2answers
51 views

Why the current decreases with increase in voltage in transmission lines? But according to Ohm's law current should increase with Voltage

Is the Ohm's law violated here? And also why is electricity generated at 11,000 V in India?
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1answer
31 views

What happens when I reverse an electrical generator?

I am trying to find out whether I could run a generator in reverse as well as forward. It will be a wind generator converted to run from a different power source. This is a new invention to which I ...
1
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3answers
68 views

Reality of “electrical explosion”

I have often heard people who have been electrocuted refer to the "explosion" and how they were "thrown back" by the "blast". Sometimes the force of the blast is reported to throw people many metres. ...
0
votes
1answer
24 views

Why the emf of a battery doesn't depend on distance between the two electrodes?

I have read that resistance of a conductor is directly proportional to its length...So ,the emf of a conductor(electrolyte of battery) should increase with increase in length/distance between the ...
1
vote
3answers
35 views

Is a flow of ionized water an electric current?

If $H_2O$ ions have a net electric charge and electric current is the flow of electric charge, can a stream of water ions be considered an electric current? If so, is it conceivably possible (not ...
0
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3answers
73 views

Given Ohm's law, how can current increase if voltage increases, given fixed resistance?

According to Ohm's law, V=IR (voltage equals current times resistance). So if the voltage increases, then the current increases provided that the resistance remains constant. I know that Voltage or ...
0
votes
1answer
16 views

Can a current source provide Voltage to a resistor?

We know that the tension between a perfect current source is 0 We have Va-Vb= 0 but we also have by ohm's law Va-Vb=RI=5V so 5 = 0?
7
votes
3answers
845 views

Which dissipates more power, a small or big resistor?

I was talking to someone about trying to dissipate the most heat from a metal crucible (essentially just a resistor $R$). He argued that you wanted the resistor to have a high resistance because ...
2
votes
4answers
194 views

Justification of root mean square [duplicate]

In the top answer to the question Why do we use Root Mean Square (RMS) values when talking about AC voltage, the following was stated: This RMS is a mathematical quantity (used in many math ...
1
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1answer
16 views

Variation of Peak Current and Peak Voltage with Capacitance in an AC circuit

The relation of Peak current, Peak voltage and Capacitive Reactance in Alternating Current is given by: $$i_m=\frac{v_m}{X_c}$$ and $$X_c=\frac{1}{C\omega }$$ So if we have a circuit with a ...
1
vote
3answers
54 views

Potential due to a continuous charge distribution on ring

Derive the formula for the potential at point $P(0,0,z)$ directly above the center of a ring of charge with radius $R$ and uniform charge density $\lambda$. My attempt: Since $$\lambda= ...
0
votes
1answer
25 views

trying to understand the electricl potential and potential energy

I am trying to understand some facts on electrical potential and potential energy. It is quite confusing in the text to say that the zero potential could be freely chosen for convenience. In that ...
0
votes
2answers
37 views

Equivalent formulas for electric current density

I am reading an article that states that the "ratio of current to the area for a given surface is known as current density" and is defined as $J = \frac{I}{A}$ where $I$ is the current and $A$ is ...
0
votes
2answers
27 views

Explain the concept of “accumulated momentum” for an electron

I need someone to help me understand this equation: $ \Delta p = qEt$ where $q$ is the charge, $E$ is the electric field and $t$ is in seconds. I thought that we were supposed to write momentum in ...
0
votes
2answers
46 views

Does turning a light off save electricity in a room heated by an electric space heater?

Suppose I've got a basement that kept heated to 20 degrees Celsius using an electric space heater with thermostat. There are no windows in this basement (light is not escaping the room in any ...
3
votes
2answers
60 views

What exactly is resistance and Ohm?

Ohm is defined as "a resistance between two points of a conductor when a constant potential difference of 1.0 volt, applied to these points, produces in the conductor a current of 1.0 ampere, the ...
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3answers
41 views

Uses of Static Electricity

Is it possible to store static electricity in any type of battery and can they be used in electric appliances(light,bulbs mainly)?
3
votes
2answers
329 views

How can there be current if all paths have same potential difference

I am learning about circuit analysis now, but there is something that I can't wrap my head around. Imagine this simple circuit: ...
-1
votes
2answers
43 views

Why in series combination of circuit has same amount of current flow in every conductor? [duplicate]

Why in series combination of circuit has same amount of current flow in every conductor? Whereas in parallel combination the amount of voltage is same?
0
votes
1answer
29 views

How long does it take for $25~\text{mC}$ to pass a point if the current is $12.5~\text{mA}$? [closed]

How long does it take for $25~\text{mC}$ to pass a point if the current is $12.5~\text{mA}$? I = 12.5mA Q = 25mC t = ? The formula for this question was: I = Q/t, where I is amps, Q is Coulombs and ...
0
votes
1answer
33 views

Parallel plate capacitor

How does a parallel plate capacitor emit a constant electric field between its plates? Isn't the electric field governed by an inverse square law? Then what would happen if I put a charged particle ...
1
vote
2answers
83 views

Voltage and resistors

I've read in many books and through many answers on this and other sites about this concept. Now I'm not sure what to "believe". In the subject at my university, we are taught that conducting wires ...
1
vote
2answers
46 views

What really causes terminal voltage?

In class we see how a current reduces the voltage across the battery if it has internal resistance. And we see that Vterminal=EMF-Ir. We don't really see the theory behind this, and I went on to ...
0
votes
2answers
30 views

In low voltage (3-12V) DC applications, which is safer to be exposed or touchable + or - terminal?

The - side has a surplus of $e^{-}$s and the opposite is true for the + side of the power supply. Does it not matter, or depends on your configuration / contact with Earth? Please explain!
1
vote
1answer
45 views

Calculate the equivalent resistance between A and B [closed]

Find the equivalent resistance between A and B. I tried using nodal but there were too many unknown variables. Please help. Thank you!
0
votes
0answers
14 views

Mechanism of Current flow in Metals [duplicate]

I do not fully understand the mechanism of current flow in conductors. It cannot be that a current starts only when an electron from one terminal of the electric supply physically reaches the other ...
3
votes
1answer
396 views

Power dissipation in circuits:Why is high voltage used in power lines?

I know this question has been asked before, but there is one doubt I still cannot clear. Power dissipation is proportional to $I^2R$. Does this not mean that it is also proportional to $V^2/R$? If ...
1
vote
1answer
35 views

Household Electricity

What is actually moving in the wires? Electrons and energy, right? With alternating current, electrons move from atom to atom, practically back and forth in the wires. Mainly, it is energy that is ...
5
votes
1answer
52 views

What experiment disproved single fluid theory of electricity?

I just can't understand how history of electricity goes on. What experiment disproved Benjamin Franklin's fluid theory of electricity?
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1answer
17 views

Binding Energy of an Electric Dipole

My question is structured in two parts: Is there any way to isolate the charges of an electric dipole? What is the binding energy of an electric dipole? To put it in another way, is there ...
1
vote
1answer
29 views

Does magnitude of a charge influence magnitude of force that individual charge exerts on another charge [closed]

two point charges, q1 and q2, are placed 0.3m apart on the x-axis, as shown in the figure above. Charge q1 has a value of -3 nano Coulomb and q2 has a value of +4.8 x10^-8 C. The net electric field ...