A third rail, also known as a live rail, electric rail or conductor rail, is a method of providing electric power to a railway locomotive or train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway track. It is used typically in a mass transit or rapid transit system, which has alignments in its own corridors, fully or almost fully segregated from the outside environment. Third rail systems are always supplied from direct current electricity.
The third-rail system of electrification is not related to the third rail used in dual gauge railways.
Is the drift velocity of gas' free electrons during the gas discharge higher than the one of the conductor's electron fliquid while the voltages supplied to these two substances are the same?
In Star Trek, they mention a Chromo-electric pulse and Chromo-electric force field. I know chromo-electric fields hold the nuclear force together with gluons but could a highly advanced civilization use chromo-electric fields for weapons or protection?
TL;DR Summary: Electronic Circuits
How do I calculate the voltage v1 using KCL?
I don't understand how I should express the current I3 to get the equation right.
I already watched this video but I don't know what to do when there are two resistors.
Hi ,
Consider Single phase induction motor.
What will be torque of induction motor, if we increase supply frequency 10 times, if the motor uses same supply current.
Let's say Torque (Supply frequency 50 Hz, Supply current 10 Amperes ) = N
What is Torque (Supply frequency 500 Hz, Supply...
I know that ##\dot e_{gen} = \frac {R_{e}i^2} {\pi r^2 L}## the thing is I don't know the value of i. I didn't write it, but another thing that the problem asks is to determine the flow of electric current. The model I came up with using heat generation due to electrical current is $$ \frac...
Can anyone explain to me why grounded means zero electric potential. I confuse what's the relation between infinite ground conducting plane and its electric potential (the method of images).
I have a several question:
1. Why the conductor plane must be infinite, while in reality there's no...
Hi!
For this problem,
Why is the area of each ring segment dA equal to (2π)(r)(dr)?
However, according to google the area of a ring segment (Annulus) is,
Many thanks!
The amount of power generated by a coil in a changing magnetic field is determined by the area perpendicular to the field, the field strength, and how quickly those values change over time, and is multiplied by the number of loops in the coil.
But that made me wonder what would happen if one...
So my idea was that to reach the equilibrium position, the final moment of force has to be 0 (so in the end the forces will “eliminate” each other). And I found the equation Fm=B*I*l*sinα, which should characterize the force, which affects wire with the current in a magnetic field, and Fleming’s...
Whether in vacuum inside a CRT, or in a metal, a potential difference has to be applied for free electrons to move from the negative to the positive terminal.
However, the reality is that free electrons are still moving when no voltage is present at the 2 ends of a metal conductor. In this...
Consider a purely inductive circuit with an inductor of self-inductance ##L## and sinusoidally varying AC source of peak voltage ##V_{m}##.
First of all, Why is ##V_{ac} = ε_{ind}## (where ##ε_{ind}## is the back emf)?
Now, at ## t=0 ##, voltage is increasing at a fast rate. Hence, due to the...
The main problem is the verse of the 2 currents ## i1 ## and ## i2 ## . I think they both go clockwise, so in the node A we should have ##i1+i2=20A##. Now let's apply the second law (going clockwise). So ##ΔV1-R1*i3 - R2*i4 + ΔV2=0##, where ##i3## and ##i4## are the currents which pass through...
I'm trying to understand the physical reason why when you drive an ideal inductor (no series resistance) with an ideal voltage step input (no series resistance), e.g. some Vin(t) = V0u(t), the output current will be a linear ramp. I can see how to derive this from the inductor equation, v = L...
I've learned that moving charges produce magnetic fields which in turn affect other charges in motion. After seeing explanations that point to special relativity, I am kind of confused. Can **ALL** magnetic fields be accounted as some kind of electric field from a particular reference frame...
Suppose we have a connected electrical network with only resistors. We also assume that each vertex is connected to at least ##k## vertices, where ##k\geq2##. Suppose all resistors in the network has resistance between 1 and 2. Suppose we flow 1 unit of current from vertex ##a## to vertex ##b##...
By the use of symmetry, I have found that equal currents will flow through opposite edges like A-C and C'A', but still, the use of kirchhoffs current and voltage laws lead to four equations in four variables which I am not able to solve, neither I am sure that the four equations which I have...
It's ABCD question with answers attached.
Problem is that, I don't think that neither of those are correct. From KVL the equation seems to be i = (E2-E1)/(2r1+2r2 + R). I've attached images of the circuit, answers, and my solution.
Can someone please point me if I am wrong, and if yes, where's...
Let's say we have a circuit, and in that circuit there's a resistor, and there's a wire that goes around it so that the current can flow freely without getting to the resistor.
my question is this: how does the current "knows" to flow towards the around the resistor? how does it know not to get...
I am trying to calculate the interaction energy of two interpenetrating spheres of uniform charge density. Here is my work:
First I want to calculate the electric potential of one sphere as following;
$$\Phi(\mathbf{r})=\frac{1}{4 \pi \epsilon_{0}} \int...
The syllabus states : "Explain that the potential difference which is needed to apply across any electric circuit to flow current is supplied by an electric source".
To explain this and make notes, I want to first understand what an electric source particularly is. And how all those electric...
This is the question: You want to make an electric instantaneous water heater in which 5.0 liters of water flows past a resistance per minute and heats water from 10.0 ° C to 45.0 ° C. Calculate the magnitude of the resistance to use and the amperage. The flow-through is connected to 230V
So...
Summary:: I am a student and i plan to study electrical electronics but i don't know how to go about it.Anyone who is into it can you please guide me on how to become one
I am a student and i plan to study electrical electronics but i don't know how to go about it.Anyone who is into it can you...
Summary:: Trying to find Rth but I do not get the same value as the one from the solution.
[moderator: moved from a technical forum. No template.]
I am trying to find Rth to solve this problem, however once I simplified it, I get a value of 700.745 Ω while in the solution, the answer is...
In my attempt, I tried
1) I1 = I2 + I3
Then set up these two equations based on Kirchhoff's second rule:
2) U1 = R1 (I2) + R3 (I3) and
3) U1 + U2 = R1 (I1) + R2 (I3).
From what we have
10 = 0.1* I_2 + 0.2 * I_3
22 = 0.1* I_2 + 0.02*I_3
I_3 = 50 - 0.5 I_2
That means
I_2 = 233.3 A
I_3 = -66.7A...
Hello,
In high school, I had been taught about finding substitution resistance from Wheatstone bridge.
The formula:
a. If the cross product of ##R1## and ##R3## is same as ##R2## and ##R4##, the galvanometer in the middle (##R_5##) can be omitted and use series-parallel principle to solve for...
Hello,
As far as I know, the standard sign convention for Kirchhoff's law are:
For resistor: the potential difference (voltage) is negative if the chosen loop direction is the same as chosen current direction through the resistor, positive otherwise.
For battery: the voltage is positive if the...
Summary: Make a circuit that counts the number of nodes in a standing wave generator
I have a an assignment to complete this Term, the assignment consist in making a machine that would produce standing waves in various frequencies, (for example the typical motor connect to a string with...
I think I have to assume a point like P in the semicircle. The point in terms of r and θ: P (r,θ).
So the magnetic field at that point:
B = µI/2π(R+rcosθ) .
So the magnetic flux:
Φ = ∫B.dA= µI/2π ∫∫ rdrdθ / R+rcosθ .
Is this the correct solution?
I am working on derivation of Lorentz force. (I know that Lorentz force is in some sense definition of fields, but still there is nontrivial dependence on velocity).
I want to derive that the force is linear in components of velocity, so for example $$F_x=q(E+Av_x + Bv_y + Cv_z ),$$where ##A...
Hello, the problem is better illustrated at the picture below.
The capacitor is isolated, with an initial charge Q0. I understand that Q0 does not distribute along the plates homogeneously. How could it be solved with the equivalent parallel circuit?
What forces are acting on electron in a circuit?
What is the source of such kind of forces?
Do electrons act on each other in electric current?
If i have an ordinary electric circuit with only one resistor, then if i raise resistance, the electric current goes down. As I understand it happens...
I suspect that at first the electrons on the other side of the plate in the capacitors are pushed to the light bulb that is the plate becomes more positive to compensate for the increase of electron on the other plate. Was this right? And can anyone refer me to a study or law regarding it?
Hi,
I've a question about electricity in the following scenario: consider an accumulator (e.g. a 9V battery) and an analog/digital voltmeter having a probe connected to the accumulator + clamp and the other to the ground (for instance connecting it to a metal rod stuck in the ground).
Do you...
This question is from 1977 AP Physics C so I suppose it would be clear enough, but I am confused about question c. Question a is easy (it rotates counterclockwise), question b too (Στ=6*rxF=6*r x (I*i x B)=0.06). Question C is where I am stuck.
The diagram provided with the question looks like...
Hello,
I am currently a mechatronics engineering student, I am working on a school project: retrofitting a tensile machine.
The goal of the project is to improve the human-machine interface as it is a very old machine, it is a JJ LOYD T20K, my problem is that the machine no longer works(it...
Homework Statement
L = 20mH = 20 x 10-3 H
i = 40 mA for t≤0
i = A1e-10,000t + A2e-40,000t A for t≥0
The voltage at t=0 is 28 V.
I have to find the equation for the voltage for t>0.
Then I have to find the time when power is zero.
Homework Equations
v(t) = L* di/dt
p(t) = L*i* di/dt
The...
Let us consider a negatively charged object. We want to neutralize this object, so we touched it by our hands to remove the excess of negative charges by Grounding. Now the question is : Will our body (The Ground) be negatively charged as it gained those negative charges? then why it is called...
Hello! today I have a question regarding the most efficient way to generate electricity by moving a magnet across a coil. The theoretical magnet would be moving in a circular motion fixed to the outer circumference of a driver wheel like in many simple generators, how does the physical torque...
1. Two identical flat plate capacitors are inserted in each other. First, none of the plates was charged, but then they have been connected to sources of current, keeping the constant voltage ## V_1 ## and ##V_2 ##. Find the potential difference between inner plates, which are kept at the...
Homework Statement
A distribution of charge with spherical symmetry has volumetric density given by: $$ \rho(r) = \rho_0 e^{ \frac {-r} {a} }, \left( 0 \leq r < \infty \right); $$
where ##\rho_0## and ##a## is constant.
a) Find the total charge
b) Find ##\vec E## in an arbitrary point...
Hello!
new here. recently I've developed an interest in the way electricity is produced, I've seen some mechanisms, most of them are steam turbine based.
i have a few questions about the topic, mainly about thermodynamics.
if i want to create enough energy to move a steam turbine that requires...
HiI was reading about capacitors and potential energy. But the equation seems counter to how i thought.
For potential energy you have:
U = Q^2 / 2C
or
U = CV^2 / 2
But doesn't this suggest you lose potential energy the more capacitance you have? Since in the first equation as C increases U...