Current Definition and 1000 Threads

<< Mentor Note -- thread moved from the technical forums, so no Homework Template is shown >> I'm studying controlled rectifiers and for full wave bridge rectifiers the notes(that I'm studying from says) It says that the average load current is Id / 2 I don't understand how. Why should the 2...

Homework Statement Hello, the question is number 35 in this picture here: http://uploads.im/uEWAf.jpg It states, ''A suitable fuse rating for the mains supply has current rating - (A)10A (B)15A (C)30A (D)60AHomework Equations V = IR P = IV P = I^2 R P = V^2/R The Attempt at a Solution I...

Homework Statement A long straight wire of radius a and resistance per unit length R carries a constant current I. Find the Poynting vector N = E × H at the surface of the wire and give a sketch showing the directions of the current, the electric field E, the magnetic field H, and N. Integrate...

If you had a box made of mu-metal and and a magnetic material inside the box, then took an insulated wire and wrapped outside the mu-metal box and applied a current, then applied a magnetic field outside the box, which one would magnetize the mu-metal, even for a brief amount of time? Also, if...

Hi, My understanding of an electromagnet is that it is a material with low susceptibility and high permeability, i.e. the magnetic field is not permanent but in the application of a current then the material gets a large magnetic field. In the application of a current the spins of the electrons...

Homework Statement Prove the following equation: ## \Delta U=\frac {R_1R_4}{(R_1+R_4)^2}(\frac {\Delta R_1}{R_1}-\frac {\Delta R_2}{R_2}+\frac{\Delta R_3}{R_3}-\frac{\Delta R_4}{R_4})E## This is used in Wheatstone bridge Homework Equations [/B] U=RI The Attempt at a Solution This has...

Homework Statement Homework EquationsThe Attempt at a Solution Output voltage and output current of an OP-Amp Taking the OP-Amp as an ideal OP-Amp, the voltage at terminal 1 is 0 with respect to ground. The voltage at B is ## V_B = - 0.5 V ## ## i_{in} ## is from A to B. There is...

Homework Statement A current at point A of 2A flows through a resistor (3 ohms), a battery of 20V (negative terminal first), another resistor (1 ohm) and a battery of 6V (positive terminal first). What is the potential difference between A and B Homework EquationsThe Attempt at a Solution I...

Hi, so I was hoping to get an EE's explanation for what just happened. So my son was apparently over by the light switch pointing a UV pen light at the switch. Suddenly there was very loud, gunshot-like pop, sparks flew, and I had to go reset the breaker. Maybe correlation doesn't imply...

Homework Statement [/B]Homework Equations [/B] I = G * U The Attempt at a Solution [/B] Hello, i know the solution is 5.0 A/V but i don't know if my way of solving this was correct. I rearranged it to G= I/U and solved this equation for all the values in the table and then added them...

its a simple circuit one branch has a resistor and its in parallel with a short i understand that the short branch has no resistance other than the wire itself which means it has super small resistance and by ohm's law I = V/R where the voltage is divided by a super small value means the...

Homework Statement Homework Equations I = VR Series = current the same, voltage different Parallel = current different, voltage the sameThe Attempt at a Solution Is the 1 ohm and 15 ohm parallel? I'm still learning to differentiate it. If yes, then R = 15/16 ohm Is the R series to 5ohm? If...

Homework Statement There is a conductor with the square-shaped area. the Radii are r1 , r2 with width b and resistivity ## \rho_R##. Find the resistance R between A and B 2. Homework Equations ##I = \iint_A\vec J \cdot d \vec A## ## \vec J = \kappa \vec E ## ## \vec E = \rho \vec J## ## V =...

I was modeling current distribution in a component: And I plotted the ##\vec J## to simulate & understand the current distribution throughout the conductor, all the flows make sense, however, at the edge of the conductor like so: Current would distribute all around the area, which is...

Homework Statement Homework Equations V = I.R The Attempt at a Solution 6 ohm and 3 ohm are series = b Then b pararel to 9ohm = c = total resistance b = 9ohm c = 9/2 ohm I = V/R I = 9.6/c I = 2,13 A Can you help me? Is it right? My friend's answer is 0,8

Hi, I'm studying the "Child Langmuir law". We have a grounded cathode that is an infinite plane with free electrons, and an anode with a positive voltage V. The text says that the current density J is constant between the two plates for the "Charge conservation principle". I was not able to...

Hi, new member with a question that I might be asking wrong. A week ago I read an article or something on building a windmill generator, which I come back to every few years. So, this week, I was reading about how to calculate the voltage based on loops, turns, Teslas, area, RPMs and such, and I...

Hey everyone, I'm hoping that you guys will be able to help me with some calculations. I was on YouTube and came across this: I then began to wonder if I could make a solenoid using bitter disk as in the video, granted no where near as powerful. I would say 1 tesla using an iron core. After...

What is the difference between the Magnetic Field Lines of the Dipole and Circular Current Carrying Wire at the centre?

Hi, I'm studying Sync Generators. In one problem I got Ia as 1.59 angle of -159.9 degrees. How do you calculate power factor for such a current? Book says Ia leads Terminal Voltage by 23.13 degrees. I guess they got that value by 180 - 159.9 But why?

Homework Statement Homework Equations Efficiency = o/p divided by i/p I/P KW divided by input voltage gives input current Field Current = voltage divided by field resistance armature current = total current - field current Back Emf = V - IaRa T proportional to Ia Back Emf proportional to...

I have created a make-shift transformer using a circular core and some wire: It is quite basic, but I have some questions about the currents induced when one side of this transformer has a 220 V AC current passed through it. I have an oscilloscope from which I have the graph: The perfect...

Hello, I was thinking that using AC to supply power to a lamp would cause it to flicker, considering that the potential difference keeps changing signs. This would mean that the current supplies voltage to the lamp, only to take it back after a really small amount of time. Voltage say's...

Homework Statement [/B] It is required to find the current through the ammeter, marked A, in the above figure.Homework Equations ##V=iR##The Attempt at a Solution I've redrawn the circuit as follows - But don't know how to obtain the value ##i_3##

Homework Statement If I have two current carrying conductor carrying current is same direction, they move towards each other so kinetiisc energy increases. So which force does work here? Homework EquationsThe Attempt at a Solution I know magnetic force can't do work, is work done by some...

Homework Statement A thick slab in the region 0 \leq z \leq a , and infinite in xy plane carries a current density \vec{J} = Jz\hat{x} . Find the magnetic field as a function of z, both inside and outside the slab. Homework Equations Ampere's Law: \oint \vec{B} \cdot d\vec{l} = \mu_0...

Homework Statement I am trying to figur out whether there is or isn t an Electric Field along the surface of a cylindrical current carrying wire With radius r and length L, current I and resistance R. I was trying to see if someone already asked this and i found one discussion, however where a...

Homework Statement In Fig. 27-66, R1= 10.0 kΩ, R2 = 15.0 kΩ, C = 0.400 µF, and the ideal battery has emf E = 20.0 V. First, the switch is closed a long time so that the steady state is reached. Then the switch is opened at time t = 0. What is the current in resistor 2 at t = 4.00 ms? This is...

I have a digital circuit , to find the energy consumed by the circuit, I am monitoring the current drawn from the supply and integrating it to get the charge pumped into the circuit ... and the total charge*V supposed to give me total energy consumed by the circuit. But I am getting a small...

Hello all, I've been pondering a problem with a current carrying wire in a magnetic field. The Lorentz force is easy, ILB, with a velocity 90 degrees to the B field. So let the force accelerate the wire. Assume only one segment of the wire that has current in one direction, say up, is in the...

Homework Statement The rotor blades of a quadcopter are 10cm long. Given that the thrust force generated by each rotor is 1N (giving a total of 4N for 4 rotors), calculate the torque () on each rotor, and the current drawn (I) from a 10V battery, given the following: Density of air, a = 1...

Homework Statement A square loop, side a, resistance R, lies a distance s from an infinite straight wire that carries current I (pointing to the right). Now someone cuts the wire, so I drops to zero. In what direction does the induced current in the square loop flow, and what total charge...

Homework Statement Find io for t≥0. Express your answer in terms of t, where t is in milliseconds. There is no energy stored in the circuit in (Figure 1) when the switch is closed at t = 0. Homework Equations ##x(t)=x_f+[B_1cos(ω_dt)+B_2sin(ω_dt)]e^{-αt}## The Attempt at a Solution Let...

I was just in a conversation with someone regarding the magnetic field resulting outside of a solid cylinder, with a current moving down the center of the cylinder, and then the resulting magnetic field after removing the current. Now I haven't thought about magnetic fields/magnets for a while...

Homework Statement Find ##i(0^+) ## and ##i(t), t≥0^+## Homework EquationsThe Attempt at a Solution [/B] I'm having trouble finding the current through this capacitor. I tried using a KVL loop for ##t=0^+##, but I'm doing it incorrectly or something. Earlier in the problem I found...

i've built a bridge rectifier with a Zener Voltage regulator. 12V peak secondary 3300uF Capacitor 1k ohm load 1k ohm series resistor for the zener and a 1n4728A Zener diode. i'm getting a 2.8V steady voltage, but when i measured the current going through the load with my DMM it's measuring...

Hi Forum I am trying to get a better grasp of the relation between electric field and the magnetic field. The overall question is "What is The origin of selfinductance in a current loop?" Here are my thourghts: A battery is connected to a say circular wire with some resistance. The current...

Homework Statement I am working on the following problem: And ideal single phase transformer 240V/2880V is supplied with a 240V source via a resistance cable of 3ohm. If we connect a R=720ohm resistance to this, determine the primary current and the dissipated power in R. (I'm sorry if some...

Homework Statement Then solve these equations for i1-4 Homework Equations V=IR The Attempt at a Solution 80i_1-50i_2-30i_3 = -120 -50i_1+100i_2-10i_3-25i_4 = 0. -30i_1-10i_2+65i_3-20i_4 = 0. -25i_2-20i_3+100i_4 = 0. i_1=-4.18239492 i_2=-2.66455194 i_3=-2.71213323 i_4=-1.20856463...

Homework Statement i'm trying to calculate the charge operator for a complex scalar field. I've got the overal problem right but I'm confused about this: On page 18 of Peskin, it is written that the conserved current of a complex scalar field, associated with the transformation ##\phi...

Homework Statement Homework Equations at point C: i2 - i3 - i4 i2 = i3 + i4[/B] The Attempt at a Solution I labeled all the currents going through each resistor in the picture[/B] for loop ABC: 2000i1 = 3000i2 + 4000i3 for loop BDC: 3000i5 = 2000i4 + 4000i3 at point C: i2 - i3 - i4 i2...

Homework Statement 1. In Figure A-1 of Experiment 18, assume that Vdc = 8Volts, R1 = 1kOhms, R3 = 7kOhms and there is no R2 resistor. Determine the current in R1 when the transistor is fully on and carrying current. Express your answer in mA. 2. In the circuit of Figure A-1, Experiment 18...

I recently watched this Varitasium video where he explains the magnetic field due to a current carrying wire. In the video he explains how what we see and describe as the magnetic field produced by a current carrying wire is actually just a electric force caused by the an imbalance of charges...

Homework Statement Find the exact magnetic field a distance z above the center of a square loop of side w, carrying a current I. Verify that it reduces to the field of a dipole, with the appropriate dipole moment, when z >> w. Homework Equations (1) dB = μ0I/4πr2 dl × rhat (2) r =...

Hi everyone - here's a concept that I'd like a few opinions on: As part of a project, I'm looking at using a brushless DC motor mounted on a high-speed vehicle as a generator. Once the vehicle hits its top speed, the batteries should disconnect from the motor and the vehicle's own velocity will...

Homework Statement I need to first find phase current in the load and line current from the supply Homework EquationsThe Attempt at a Solution I thought it would be easier to work with a star because then the Ztl would be in series with it... I am not sure how to find the current but my best...

Homework Statement Many experiments in physics call for a beam of charged particles. The stability and “optics” of charged-particle beams are influenced by the electric and magnetic forces that the individual charged particles in the beam exert on one another. Consider a beam of positively...

Homework Statement I have a solenoid with a wire carrying current in the center. The wire has a radius of a, the solenoid has a radius of b. I need to find the magnetic field inside of each region. Inside of the wire, mu =/= muo. Homework Equations Wire B field = uo I/2*pi*r Solenoid B field...

Homework Statement "The switch in the circuit in the figure has been closed for a long time and is opened at t = 0. Find i(50 ms)." I attached an image of the circuit below.Homework Equations KVL: Ri + q(t)/C - q(0)/C + vc(t) + Li' = vs(t) Li'' + Ri' + i/C = vs'(t) Where vc is voltage across...

In node analysis, after labeling the nodes. I don't know how to choose currents direction to apply KCL. it seems too complicated.. and I end up every time getting different answers the the solution sheet. I've an exam tomorrow. would be much appreciated if you could help me better understand the...