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

learn more… | top users | synonyms

0
votes
2answers
36 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
21 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 ...
0
votes
2answers
26 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
votes
0answers
57 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
0answers
23 views

Conceptual resources for understanding Physics [on hold]

Before I ask my question, I would like to note that this is a request for resources, and not a question dealing with the principles of Physics. Conceptual tools help us bridge our perception, ...
0
votes
0answers
27 views

Is there transversal current inside real conductor in transmission line? [on hold]

At first, consider transmission line with two conductors where TEM mode is established and conductors are perfect. As we know, on surface of conductors we will have surface currents (connected to ...
0
votes
2answers
45 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?
0
votes
1answer
29 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
vote
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
23 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
votes
3answers
69 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
824 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
191 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
vote
1answer
14 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
51 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
24 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
36 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
26 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
45 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
59 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 ...
1
vote
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
326 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
27 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
80 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
44 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
29 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
391 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
51 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?
0
votes
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
28 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 ...
3
votes
0answers
15 views

If you toss a handful of confetti onto a comb, why does some of it stick and some of it fly away?

My guess is some paper pieces happen to be charged with the opposite charge compared to the comb, so they are attracted, but once they touch the comb, their charge is neutralized. But the comb is ...
4
votes
2answers
172 views

Voltage drop due to a resistor

I'm afraid this question is going to sound rather dumb but here it is: Suppose I have a very simple circuit: one battery and one resistor. The sum of the voltages in this circuit has to equal zero. ...
1
vote
3answers
102 views

Why is equivalent resistance in parallel circuit always less than each individual resistor?

There are $n$ resistors connected in a parallel combination given below. $$\frac{1}{R_{ev}}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}+\frac{1}{R_{4}}+\frac{1}{R_{5}}.......\frac{1}{R_{n}}$$ ...
0
votes
1answer
34 views

Why is the loop rule from circuit theory applicable for 'any' loop?

While proving Kirchoff's loop rule in class or any physics book, we take a simple one-loop system for the proof. In such a case, the current actually goes round the loop and the same current flows ...
1
vote
1answer
48 views

Speed of a charge in a magnetic field

Does speed of a charged particle change in a non-uniform magnetic field? I know that a uniform magnetic field cannot change the $KE$ of the particle, i.e. $\frac{1}{2}mv^{2}$ is constant. And we ...
1
vote
2answers
40 views

What causes the random movement of particles inside a conductor?

I'm reading about currents in electricity right now, and it was mentioned that even if there's no electric field inside a conductor, charged particles inside are still undergoing random movement. I ...
2
votes
3answers
59 views

Electron flow in a wire [duplicate]

How do electrons that constitute a current flow move in a wire? Some say it's like a wheel.If you give it a push,every part of the wheel moves instantly. Is that what happens to electrons?Do they ...
-1
votes
1answer
28 views

Difference in the amount of heat produced in two circuits having two different metals

There are two circuits to the first nichrome is connected like this and in the other a copper wire instead of the nichrome wire when electricity is passed through which wire gets more heated? Since ...
1
vote
1answer
18 views

Can data be transmitted from one object to another one during electrostatic discharge (ESD)?

Did this ever happen to you?, after you touch something (or someone) 'Ouch'! you get a static electric shock. Can (any kind of) information be transmitted between two people during accidental ...
1
vote
1answer
42 views

Why is the current in an electric circuit constant?

Considering electrostatics, suppose we have two charges of equal value and opposite sign and we put electrons along the road between them: We know that the electrical force or field is different from ...
1
vote
2answers
52 views

What is the difference between a circuit with a resistor and one without it in energy terms?

In Fundamentals of Physics (HRW), an equation is derived for the current in a circuit in terms of its emf and resistance by the 'Energy method'; that is, deriving emf=i.r and saying that the work done ...
0
votes
1answer
45 views

Potential Differences (Voltage) from Point Charges [closed]

Identical +1.8 micro Colomb charges are fixed to adjacent corners of a square. What charge (magnitude and algebraic sign) should be fixed to one of the empty corners, so that the total electric ...
3
votes
2answers
94 views

Will a microwave heat sand?

I want to cook Turkish coffee on heated sand at school. I have difficulty accessing some easier method of heating, so I was going to try to heat sand in a microwave. It was then pointed out to me that ...