Current Definition and 1000 Threads

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...

i have seen several videos of thyristors but they never really explain the fundamentals they just say that cause there is a current flowing in there it keeps being on but why does a transistor then turn off when you remove gate voltage

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...

In my opinion, the voltage across the C1 should be 9V as the potential on the side of the positive plate of the capacitor should be (15-6)V and on the other be 0V. Similarly the potential across C2 should be (7-0)V. Here I'm basically assuming that the voltage at the negative terminals of the...

Hello, I have answered the question below but would like some advice on whether I can improve my answer or if anyone is able to check whether I have made any mistakes ? i. 1 V = 1eV in a 1:1 relationship, therefore; 6.5 TeV = 6.5 TV = 6.5 *10^12V ii. E=W W=V * Q Q=number of particles * charge...

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...

I know only about Laminated,Iron and wooden coil.I don't know what is Air cored coil. So according to me,it should be Wooden cored coil because less current will flow through wooden cored coil.Ans it will be maximum in Iron cored coil. Please tell,am I correct or not?I don't know the answer.

a. No, because only permanent magnets are suitable to be used as a compass. b. Yes, but only if the coil doesn't have an iron core. c. Yes, but only if the coil can turn easily. I choose (c) , Is that correct ?

a) Here I used the definition of current (reference: Tong notes, page 14) $$j^{\mu}_{\nu} = \frac{\partial \mathcal{L}}{\partial (\partial_{\mu} \phi_a )} X_a (\phi) - F^{\mu} (\phi), \ \ \ \ \ \ \ \ \delta \mathcal{L} = \partial_{\mu} F^{\mu}; \ X_a (\phi) = \delta \phi_a$$ In our problem we...

Preface to thread: The power source in both diagram 1 and diagram 2 is a wall outlet with alternating current power, not a battery. The load in both diagram 1 and diagram 2 is a light bulb, even though I forgot to label the load in diagram 2...

Hello there! I have seen some great eddy current brakes and wanted to learn more about it. The problem in the internet I can not the specific case I have in mind. I searched the internet and found a great deal of material about magnetic forces. I cannot, however, find the specific case I'm...

in an LC circuit the current does no drop to 0 but varies sinusoidally. The capacitor is recharged with a different polarization. Why is this so?

I'm trying to understand the valley degeneracy to calculate the tunneling current. Here is the equation of tunneling current.$$I_T=q\frac {g_sg_v} {L} \sum_{k} v_g(k)(f_v-f_c)T$$ ##g_v## is valley degeneracy. I thought it comes from the symmetry of structures, depending on a certain point in...

Hi, I've been stuck for a long time with this exercise. I am not able to calculate the potential vector, since I do not know very well how to pose the itegral, or how to decompose the disk to facilitate the resolution of the problem. I know that because the potential vector must be parallel to...

These are images from the book Introduction to Electrodynamics by David J. Griffiths . . . My problem is that I'm unable to understand how the current has zero ##\phi## component (I have underlined it in the first image)? I do understand cylindrical coordinates, I know...

An interview on NPR with virologists discussed the reasons that this current viral pandemic is different than others in the past. Key differences were: - Ability to make new viruses - apparently 1000 times more prolific than flu. - Unlike flu viruses, it does not appear to mutate because it...

On the left: my copy of the illustration in the problem. On the right: top view, with the angle. The problem gives the magnitude of the magnetic field, the radius of the rail, the resistance of the resistor, the initial rotational frequency of the bar. I am able to obtain the given solutions...

In the circuit below, the output is 23 W across the resistor with the resistance 6 Ohm. Calculate the amount of current in all parts of the circuit as well as the polarity and EMF ε of the unknown battery. Circuit: My attempt: I get 6 unknowns with 5 equations. I don't know how to find the...

I was thinking of a standard, high school level discussion of the displacement current. The need for introducing this quantity is demonstrated by considering a circuit with a charging capacitor, and (for the sake of simplicity) a circular loop whose axis is along the (straight) wire carrying the...

I made this scenario where I am looking for the total current running through a wire (I_0). I am also trying to model the current running through the wire (I_0) considering the harmonics contributed by the four loads. But since Fourier stated that a complex waveform is the discrete sum of some...

I don’t know the ratio of the CT. I’m just looking for an explanation on this. I thought in order to measure output voltage you need to pass the current through a resistor and read the voltage drop. A co worker put 400a through the CT and measured 130v. Something just seems off to me. Can you...

I = A_0 * sin(n_0wt + p) + A_1 * sin(n_1wt + p) + ... +A_n * sin(n_nwt + p) Looking at the equation, it only contains sinusoidal waves. Further, there is the possibility of waves having the same shift or no shift at all and even, having the same frequency. Is it really valid or correct to use...

So if I have a source of 5V and 20 amp then the maximum power I can get from the source will be: $$ P_{max} = 5*20 = 100W$$ but my load can only take in 5 watts, it will blow up. But, does this have to happen or does my load only take what current it needs? My guess is that the load takes in...

I’m self taught so I have a lot of holes in my understanding. I also have little to no mathematical understanding. Even though ironically, I tend to prefer to picture electricity as numbers rather than “water” in a pipe, etc. I’ve been studying displacement current recently and have a question...

No attempted solutions.

My son and i were discussing aerodynamics and he brought up a paper from https://phys.org/news/2012-01-wings.html It seems that the latest discussions seem to completely discount the differential velocity of air flow as a cause of differential pressure, but point to a differential pressure...

If we take electric current to be the rate of flow of (signed) charge past a certain point in a given reference direction, this unambiguously tells us all the information that we need to know. If we label a current arrow with ##-6A##, then in ##1## second we either think of a charge of ##-6C##...

Hi everyone I have drawn what I think what the setup should look like, and worked out the equivalent resistance of the parallel connected resistors Not so sure where to go next with this problem? Any help would be greatly appreciated!

Is the four current in relativity an invariant quantity? I know the divergence is zero for the four gradient, i.e. the continuity equation. But is the four current a vector in the sense that it has invariant properties?

Consider the following experiment: from a lacquered copper wire we cut off twenty to thirty pieces of about 10 cm. From them we form a bundle of parallel wires and connect the two ends with one more wire each. The other ends of these two wires are connected to a sensitive analog ammeter. We hold...

Hi there! I have recently been given this question by my teacher as shown below I'm struggling to see the set up arrangement for this circuit This is what I have drawn so far How would I fit in the third wire here and ensure I have closed loop circuit so that current can begin to flow...

Sorry if the answer is obvious, but I was wondering if positive and negative electrodes (cells in series) can share the same current collector as depicted below? I want to create a 12V battery with cells inline in series without creating cells with individual current collectors. Note that the...

I can create a fairly strong magnetic field by leading current through a copper coil. However, I cannot then with that magnetic field create a current (not a useful one at least) in an object made out of copper. I understand that this is because copper lacks of magnetic properties. For instance...

I was reading about ideal current and voltage amplifiers and the book says that an ideal current amplifier should have 0 input impedance and infinite output impedance while an ideal voltage amplifier should have an infinite input impedance and 0 output impedance. I am not quite sure I...

This is the problem, first time i am attempting the Ampere's law problem From the above question this is my attempt, the picture is ∫B.ds = μ*Ienc; ----> Ampere law , where Ienc is the current enclosed in the amperian loop. I assume the circle as the amperian loop, is it correct? Can i...

Why when a certain current limit is breached is superconductivity destroyed in a material, what atomically causes this effect when J > Jc? Secondary question what causes H0's value to be higher or lower atomically and chemically for a given material?

Here are a few problems I have been trying which are shown below Here is what I have done The correct answers for these Q's are: I'm not sure what I have done wrong for Q4, I assumed that all 12 cells were connected in series thus each individual emf sums up to 24V Similarly the...

Greetings, I realized that I don't understand a fundamental fact of common Li-ion batteries. During the charging process, electrons are forcefully extracted from the cathode and pushed into the anode. Charge balance then yields a flow of positive Li ions from the cathode to the anode (through...

In my idea the tension change after connecting the circuit to a battery is immediate, while the current takes some time before moving. That should be sufficient to prove my question but, so why in a RC circuit the opposite happens?

Summary:: I was trying to derive the equation for the output impedance of the ICIS circuit. Here's what I've tried so far. What I have derived does not agree with the one provided in my book. Since it is a current source the negative feedback must increase the output impedance. The one I...

To find out what the induced loop current was i used the formula: V=R×I To find out what the value of V was i used the formula that links electromotive force (fem) to angular speed: Fem=ω×B×A The only thing that's missing is the loops area but considering that it's a semicircle and that the...

We are given that ##i_D = 8\cdot 10^{-12} (e^{v_D/20m} - 1)## Hence ##i_D' = e^{50 v_D}/2500000000## and ##i_D'' = e^{50 v_D}/50000000## Then I have that ##\delta i_D \approx\frac{ e^{50 v_D}}{2500000000} \cdot \delta v_D = \delta v_D / 5## Cancelling ##\delta v_D## from boh sides and solving...

I honestly don't know how to quite even begin this problem. Looking at Fig 3-2, the slopes of the graphs are 1/R, and hence where the slopes are 0, we have infinite resistance, in which case current wouldn't flow through that resistor and hence simplify the circuit. So I was trying to find...

From the circuit I have: ##-v_b + v_a + V = 0## ##v_b - V = v_a## ##i_1 = (v_b - V)/R_1## ##I + i_2 = i_1## ##(v_b - V)/R_1 = I + v_b/R_2## From this last equation I get ##v_b = 10.8## and hence ##v_a = 5.8##. However, apparently that is wrong. (And hence my answers to #2 were all wrong as...

Hello, I start by applying the integral for the vector potential ##\vec{A}## using cylindrical coordinates. I define ##r## as the distance to the ##z##-axis. This gives me the following integral,$$\vec{A} = \frac{\mu_0}{4\pi} \sigma_0 v 2 \pi \hat{x} \int_0^{\sqrt{(ct)^2-z^2}}...

I don't get this. Since we have analyzed the circuit separately for each source, adding them should give me the final values of I1, V2, I2, V1 etc. However, that's not quite true—from cases 1 and 2, I should have I1 = 4 + 5 = 9 mA, but it's 8mA. Hence, I thought that the black box consumes 1mA...

I have no problem getting the ##R_{TH}## since from the special element's POV, the resistors are in parallel, and that's the answer. However, I don't really understand how to get ##V_{TH}##. Ignoring the special element, it seems that I have the resistors in series this time. But I'm not too...

I don't really understand or see the correct way to approach this. Letting the current in question be ##i_x## (as shown in Fig. 1), and the unknown (changing) resistance be $R_x$, I can write: ##-V_s + R_s i_s + i_x R_x = 0##, and ##R_p i_p = i_x R_x##. Hence we can also write ##-V_s + R_s i_s...

I need to do question 1. I understand the right hand rules but am lost on what to do here.

I found the Req which is 13.6 and also found the It which is 0.74. I'm having trouble finding the separate current and potential difference numbers.