Current Definition and 1000 Threads

I'm a mechanical engineer by trade, but I am working on developing a testing apparatus that oscillates a neodymium magnet between two solenoids offset by by a 180 degree phase shift. Basically, one solenoid pushes, the other pulls. To get this, current is essential. I need each solenoid to get a...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > in the solution sheet, He took the 18 ohms parallel with the 9 ohms and not the 6 ohms. I don't understand why he took this approach. I was going to take 18 ohms parallel with the 6 ohms and find...

Basic Question Alert ! (I need to brush up my basics and need your help) Problem Statement: I wish to make a current carring cable loop to generate a controlled magnetic field. http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/curloo.html As I understand, the magnetic field generated depends...

I am doing a series of videos on the history of electricity and I am working on a video on Volta and the first battery. Anyway, I want to compare the voltaic pile to a typical li-ion battery running my iPhone. Now the voltaic pile could easily create 20 V of potential but it had high...

Hi, I need to calculate the current in a 400nm piece of graphene. Can some one help me please? I found online that graphene has electron mobility of 200,000 cm^2/( V s). My best attempt is as follows. Using the equation vd = uE where E is the magnitude of the electric field applied to a...

Homework Statement The current source and voltage source in the circuit shown in the Figure below are connected in parallel so that they both have the same voltage, vs. The current source and voltage source are also connected in series so that they both have the same current, is. Suppose that...

In my physics textbook it says that ammeter in circuit C shows higher current than ammeter in circuit A and D. And the voltmeter shows higher voltage in D than in B, and C. It's explained in the book that way: some electric current is passing through the voltmeter in C, thus the ammeter will...

Does anyone know of a simple relation between dark current and dark count in photon collection devices?

I have a silly question. In a simple electrical circuit, we know that the two ends of the wire are connected to different potentials of a battery through the load. Potential difference causes the current flow. But how the wire comes to know that the other end of it, is connected to different...

Greeting . It is clear to me that the resistor represents a physical obstruction to the passing current I do not know how exactly it works and I will try to show what I was really interested in the diagram.

Homework Statement 1) what is the total resistance of this circuit between points A and B? 2) if the horizontal resistor was replaced with an ammeter what would it read if a 6V battery was placed between points A and B? let R = 20 ohms Homework Equations The Attempt at a Solution had...

Homework Statement A 2400-turn solenoid is 2.4 m long and 10 cm in diameter. The solenoid current is increasing at 1.4 kA/s . Find the current in a 5.0-cm-diameter wire loop with resistance 9.0 Ω lying inside the solenoid and perpendicular to the solenoid axis. Repeat for a similarly oriented...

I am trying to formulate the Current Density for a Loop of wire with a diameter,d, current,I, and an cross-sectional Area of the wire ##\pi(d/2)^2##. With spherical coordinates (radial, azimuthal, polar) ##\bar j## = ##\frac{I}{\pi(d/2)^2}*cos \theta *sin \phi \hat x##...

If a current flows in a straight wire, a certain amount of magnetic flux will be generated around it. Now suppose I put an iron tube around the wire (but don't change the current). I know the inductance will increase, but is that because more total flux is now being generated, or is the total...

Given the circuit in the diagram I was wondering would I be able to make ib equal to the mesh i3. I have the equation for my Super Mesh at i1 and i3 which is: -25+30i3+5Va+20(i3-i2)+10(i1-i2)=0 (1). The mesh i2 is equal to -2A (2). subbing (2) into (1) gives: -25+50i3+5Va-30i2+10i1=0 (3)...

Hello Everyone, Could anyone please explain the difference between the conduction current density (J=σE) and the convection current density (J=ρvd)? I really appreciate any examples or applications to further elaborate these two theories. Note: vd is the particles' average drift velocity...

Homework Statement I am working on this problem. They start out by giving me: I am asked to find Rref such that Vcc=8V and Icopy=0.38mA. Homework Equations Transistor equations The Attempt at a Solution In this case, they never specify if IB=0A (sometimes it does ?) but I would assume that...

Faraday's law states that emf is proportional to change in flux. The scenario I am using is a magnet is moved towards a closed loop. As it moves towards the loop, flux through the loop is increased causing a emf to be induced. Does I also know that a current is induced. So does that mean current...

Hi, so the scenario is that the primary coil of a transformer is attached to a battery in a circuit with a variable resistor. The resistor is set to the maximum resistance. As I increase the current in primary coil by reducing resistance at a constant rate, will the current in the secondary...

For a Dipole and a Torad (or a Solenoid) I need to find the scalar Potential,phi, Charge Density,rho, and then 4-Electromagnetic Current,J(rho*c,j) where A and J are 4-vectors and a and j are 3-vectors. -grad^2(phi) + 1/c^2*d/dt(phi) = rho/epsillon0 where grad(A(phi/c,a)) = -1/c^2*d/dt(phi)...

Hello I'm working through a book (with answers) but am struggling with voltage, current, resistance and circuits. Please check my understanding below and let me know if I've finally understood. Thank you. In particular I'm confused in Q2 Q1. A student connects light bulbs, A and B, and...

Homework Statement [/B] Hey everyone, I recently got two problems on capacitance and inductance and need some help on them. Here are the two problems: 1. A Royal Red Robin Burger contains 1230 food calories. Also, more that the daily requirement for protein, fat, sodium ..., even without fries...

Hello everyone, Recently, i have designed a capacitor bank for a company which they already have their main switch board with metering stuff. The ammeter of the main switch board has its own CTs but for the capacitor bank I need to install a CT separately. The spec of existing CTs for main...

My question is :what is the role of neutral conductor in the 230v European single-phase system .My assumption how it works that a neutral conductor serves to close the circuit between phases and to carry the imbalance current between different phases If all the phases are balanced then the...

I have to configure a power system for a furnace which demands very high current of the order of 50KAmps with low voltage of the order of 100 volts. Can anyone help me to get insight into how to configure the power system in boarder way. I am planning to use a transformer with thyristors .

Homework Statement A half wave rectifier circuit has a transformer inserted between the source and the remainder of the circuit. The source is 240Vrms and 60 Hz, and the load resistance is 20ohms. 1) Determine the required Turns Ratio of the transformer such that the average load current is...

How can I increase the output current from a piezoelectric trasnducer using PZT ceramic? The requirement is about 1.2 Amp but currently I'm only getting about 0.2 mA per unit.

Homework Statement A 120-V generator is run by a windmill that has blades 2.0 m long. The wind, moving at 12 m/ s, is slowed to 7.0 m/ s after passing the windmill. The density of air is 1.29 kg/ m3. If the system has no losses, what is the largest current the generator can produce? [Hint: How...

Homework Statement In an AC circuit of periodic current we know: ##E=6[V]##, ##R_g=50[Ω]##, ##L_g=\sqrt3 [nH]## and ##ω=50*10^9[s^{-1}]##. Calculate: a) All available power of the ##E## b) The resistance of ##R## so that the average power is max c) That average power from part b) Homework...

Homework Statement What is the current through the resistor marked 'R' in all three circuits just after the switch is reopened after being closed for a long time? The Attempt at a Solution The explanation that we were given for (1) is that I = V/2R and (2) I = V/3R and (3) I = V/(R/2) but I...

i was reading about CSI and the first paragaph said "A constant current source is assumed here, which may be realized by using an inductance of suitable value, which must be high, in series with the current limited dc voltage source. " and it says nothing else about it , so clearly it's a basic...

G'day guys So I currently have a 2x 8" stoke 150lbs dynamic force actuators with a maximum current draw of 5A. The exact one is the FA-PO-150-12-XX in the link below: https://www.firgelliauto.com/products/feedback-rod-actuator The load I have on it causes the actuators to draw almost its'...

All sites and books give different answers for this question:( Homework Statement predict the polarity of the capacitor in the diagram below Homework Equations right hand thumb rule AB is capacitor The Attempt at a Solution The side facing south pole becomes south and north facing side...

Hi, I'm trying to form an expression for a rectifier supplying a DC link with current, without actually rectifying a 3-phase input. Usage of the model is really only concerned with the RMS values and the active power drawn from the AC supply. The DC link is just a capacitor so that: dVDC/dt =...

Homework Statement In Fig. 32-4( a) there is a uniform magnetic field in the + x-direction, with a value of B = 0.20 T. The circular loop of wire is in the yz-plane. The loop has an area of 5.0 cm2 and rotates about line CD as axis. Point-A rotates toward positive x-values from the position...

Homework Statement Homework EquationsV = IRThe Attempt at a Solution For the first question, I understand that mathematically, the resistance is decreasing even though the graph is linear (R = V/I, and this ratio decreases with every increase in V). However, I don't understand why this...

Do alternators obey Ohm’s law? The alternator output voltage is proportional to the rotor excitation current. When reducing rotor excitation, the output voltage drops and the load resistance stays constant. Can why still use ohm law to determine the output current. Example alternator 480 v / 4...

Dear All, This is my first question to the forum. "Assume there is a + dc voltage across a inductor. So current will continue to increase. Now if the current through the inductor is forced to stop using some means ( eg. Current was flowing in inductor through a ON switch and then switch turns...

Homework Statement Homework EquationsThe Attempt at a Solution I solved the first part. I = 4πσV/(1/a - 1/b) Here, it is solved assuming that both the shells have positive charges and the charge flows from the inner shell to the outer shell . So, in the part c, it is assumed that each...

Homework Statement Homework Equations ## V=IR## The Attempt at a Solution This is an I-V graph so the slope must represent ##\frac{1}{R} ## Now, $$ R∝Temperature$$ {This is assuming that the wires are of metal} Now , since the graph is of ##\frac{1}{R} ## , the steeper the slope the higher...

Hi there, I attached an image of a basic linear motor. I'm a little confused if I use the right hand rule or left hand rule. I did it both ways and I think the left hand rule is the only rule that allows for a force being applied to the right. I assume the current is going down rather than...

My thoughts are concerning an infinite sheet carrying current in a direction. I wish to induce a unidirectional electric field outside of the sheet via induction. My ideas were that if the current was changed linearly in a sawtooth fashion, then I would achieve the induced electric field in...

Why are they circular? You know, like this: Why not straight toward the wire?

Homework Statement In Fig. 26-5, how large must R be if the potential drop from A to B is 12 V? (The figure has been pasted into the attached file). The answer to this problem is 3.0 ohms. I keep trying to solve this problem but I get a wrong answer. The answer I get from my calculations does...

Hi, I am looking for some information regarding maximum current density in conducting mediums, such as a conducting fluid. Say that we have a setup like the figure that I have attached. We are looking down on a conducting medium with a uniform magnetic field coming out of the page and the...

Homework Statement Res-monster maze. In Fig. 27-21, all the resistors have a resistance of 4.0 and all the (ideal) batteries have an emf of 4.0 V. What is the current through resistor R? (If you can find the proper loop through this maze, you can answer the question with a few seconds of mental...

Hi, initially I would like to share this link related to derivation of maxwell equation : http://www.physicspages.com/tag/amperes-law/ My question is : in this link, it states interesting situation in electrodynamics is one where the current density is constant in time, but the charge density...

how we can mathematically prove that in a purely inductive circuit current lags behind voltage by a phase angle of π/2?

Please explain me the following answer Q)When a current is passed through a conductor, will it be charged? A)Charge carriers participating in conduction in a conductor are not excess charge carriers. The number of free charge carriers is equal to the number of opposite charge on the nearly...

If there is a rotating wire in a constant magnetic field what is the direction of the induced current ? The problem is the direction of the area vector which is arbitrary, if it is parallel to the magnetic field the current will flow in a direction, if it is anti-parallel it will flow in the...