Current Definition and 1000 Threads

  1. X

    Current flow in a two source circuit

    Hi guys, is the current flow in this picture correct? I'm trying to understand current flow in a two source circuit.
  2. M

    Lethal Voltage vs. Current: Exploring the Truth Behind Electrocution

    Hi there, I have very big doubts about this. I keep hearing that it's not the volts that kill you but rather the amps. 60 mA are supposedly enough to kill a person. Let's consider a person with 100.000 Ω resistance. If V = R⋅I, then V = 0.06 A ⋅ 100.000 Ω = 6000 V, and that would be the...
  3. R

    Calculate the RMS current of an ac circuit

    Homework Statement : [/B] calculate rms value of current i= 3+ 4 sin(ωt+π/3)Homework Equations : [/B] Irms2=(∫0T [I(t)]2dt)/TThe Attempt at a Solution: I tried to integrate but I'm getting a T term.
  4. Harshna

    Engineering Find Currents I1 and I2 in an Electric Circuit

    Homework Statement I need to find the currents I1 and I2 in the attached image, but am having some difficulties grasping the concepts. I am given E(t) = 338sin(t) as well as values for R, L and C. I think I know what I need to use but I am not sure how to put it all together Homework Equations...
  5. V

    Induced current in an inductor

    I am struggling with the concept of induced current in a circuit consisting of an inductor and how that induced current establishes back EMF . Please see the page of the textbook attached . There is a circuit consisting of an inductor , a series resistance (not shown) and a battery ( not shown...
  6. C

    What are the difference between electrical current and RF?

    Hi. This might be really basic. But I am really struggling to grasp the difference between electrical currents such as AC and DC and RF. For the case of AC current, it alternates currents at a certain frequency.. which makes me wonder how AC and RF are different. Also, if you could, could you...
  7. R

    Electric Current and Potential Difference

    when the external electrical potential difference is applied across the conductor ,electrons flow in the direction opposite to the current.Whether the number of free electrons in the conductor decrease?
  8. B

    Engineering How Is Current Linkage Constant in a Salient Pole Motor's Amperian Loop?

    Homework Statement I have a doubt about the current linkage, Θf, in figure 2.2b of a salient pole motor. In this textbook, the current linkage is expressed by ∫H⋅dl = Θf = ∑i. However, in the figure 2.2b between q(left) and q(right), how can the Θf be constant? Since, the author doesn't show...
  9. A

    Induced current in magnet (what would happen if....)

    Homework Statement Homework Equations N/A The Attempt at a Solution [/B] I'm having a lot of trouble understanding induced magnetic fields. I was wondering if someone can explain it for me and confirm if I have the right answers? a) I labelled it [North | South], and the direction of the...
  10. Wrichik Basu

    Neutral wire in electric power distribution between substations

    I had learned from a book in a lower class that electric power distribution from the generating station is done in phases. Like in India, we have three phases of power transmission: the red, green and yellow colours distinguish the three phases. I believe the same is the case in any other...
  11. Wrichik Basu

    Understanding the Flow of Electrons in AC Circuits

    In DC, we have learned that the electrons move from their position through the conductor, resulting in a current. They leave their positions on the application of a potential difference, and move or flow in the direction of higher to lower potential, thereby causing a current. But what about...
  12. G

    Engineering Voltages and current in a circuit: incorrect signal?

    Homework Statement Consider the circuit in the figure and calculate V1, V2 and IA. Notice that the symbols V and A represent, respectively, an ideal voltmeter and an ideal ammeter. Homework Equations Ohm's Law $$V=RI$$ KVL The sum of the voltages of a mesh in a circuit equals zero. We...
  13. S

    What Is the Formula for Solenoid Magnetising Current?

    Homework Statement Part d of attached question Homework Equations Solenoid equations B=uo n i The Attempt at a Solution B (absence)=B (presence) Uo n (i+im)=u n i im=798A But answer is 794A.[/B]
  14. Y

    What force does the current carrying coil feel?

    Homework Statement What direction does the force that the current carrying coil feel point to when a magnetic field is turned on? A magnetic field is turned on and points from bottom to top and passes through a current carrying coil that has current passing through it CCW. Here is a diagram...
  15. davidge

    Can quantum mechanics be used to explain electric current in materials?

    Electric current can be studied using classical electromagnetism. In that case, the explanation is that there is a net flow of free electrons through a wire, say. Looking more close on the situation, what happens is that there is a difference on the energy level of some atoms and electrons can...
  16. A

    Calculating/3D Modeling Salt Water Current Paths

    Just to clarify, this is not a homework or coursework question. I was wondering, if you have a large container of salt water and place two electrodes on either side, the current will pass from one electrode to the other through the salt water medium. Is the a way to calulate or 3D model the...
  17. T

    Relation between current and flux

    So I learned that voltage/emf is proportional to the negative change in flux so the graph of the voltage is the negative derivative of the flux graph. What is the relation between flux and current. In a motor, a change in flux induces a current that creates an opposing magnetic field, and...
  18. T

    How to Calculate Current Density (Petri Dish/Graphite 0.7 mm)

    Hello all, I have a petri dish 8.7 cm in diameter filled with 20 mL of TSB media. I have set up a .7mm graphite at the 0cm mark of the diamter and measured current at 4.6Volts over the entire distance of the petri dish (8.7cm) with .5 cm step sizes. For example: When the probes are 1cm apart I...
  19. Q

    Relationship between line current & surface current density

    Homework Statement In a configuration having axial symmetry about the z axis, a line current I flows in the −z direction along the z axis. This current is returned at the radii a and b, where there are uniform surface current densities Kza and Kzb , respectively. The current density is zero in...
  20. R

    Calculate current flowing from one cylinder to another

    Homework Statement Two long concentric cylinders of radii .04 m and .08 m are separated by aluminum. The inner cylinder has a charge per unit length of \Lambda at any time. When the two cylinders are maintained at a constant potential difference of 2 V via an external source, calculate the...
  21. C

    Resistance, Voltage, and current

    Homework Statement Homework EquationsThe Attempt at a Solution I chose A, I understand how the resistance is the gradient, but if it is the gradient and the gradient is constant , shouldn't the resistance stay constant? (But the answer is B) Please help~thanks a lot~
  22. C

    Resistor and current in a circuit

    Hello , I have to teach a group of 9th grade students role of resistor in a circuit and how it affects the current in the circuit . This will be their first exposition to circuits .So I need a good and simple analogy so that students can grasp these concepts easily . This is what I plan to...
  23. prakhargupta3301

    Why isn't the Heat generated = Voltage*Charge carried?

    I found out that Power of an electrical circuit will be equal to the work done divided by the time T for which the power by the cell or battery is exerting to keep a potential difference V in the circuit for a charge Q. Hence, Power= Voltage*Charge/time Which then can be written as: Power=...
  24. B

    How does using a 12v starter motor on 24v affect power and current draw?

    hello, if i use a 12v 1.2kw starter motor on 24v. how the power will change and how much current will it consume.
  25. Ken Gallock

    I Lorentz transformation and its Noether current

    Hi. I'd like to ask about the calculation of Noether current. On page16 of David Tong's lecture note(http://www.damtp.cam.ac.uk/user/tong/qft.html), there is a topic about Noether current and Lorentz transformation. I want to derive ##\delta \mathcal{L}##, but during my calculation, I...
  26. G

    Eddy current losses in microelectric generators?

    For a microscale electric generator (where the driving force is a fraction of a Newton), can losses from eddy currents be significant enough to noticeably alter the rotational velocity of the rotor? Because my understanding is that the rotation is basically taken as a constant when examining the...
  27. B

    How do solar cells generate current from pn-junctions?

    Looking for a practical description. I have a feeling I am grossly misunderstanding something fundamental about electric circuits and apologize if my questions are confusing because of it. I have these two sources: acs hyperphysics My (probably naive) understanding of the process is as...
  28. R

    Vibrating a loop with current - will it radiate?

    Hi, I am new here so hopefully this is the right place to ask a question like this. Forgive me if I have trampled a rule. If I have, please let me know what I should do to ask this question. If you take a wire with a flowing DC current and vibrate it, can it radiate as a radio transmission...
  29. S

    Short Circuit Current on 161kv line

    I work at a electric arc furnace. We measure a lot of items on our furnace and found that some weeks we preform well and other we do not (kwh/ton). With everything else being equal i believe that the utility's available short circuit current is affecting this. The utility feeds our substation...
  30. S

    How Does Current Direction Affect Magnetic Field Orientation?

    Homework Statement current in wire is in east to west direction.direction of magneetic field below the line Homework Equations right hand thumb rule The Attempt at a Solution i used the right hand thumb rule to find the direction of magnetic field but the magnetic field comes out in in the...
  31. T

    Torque on current carrying loop/Diploe moment of loop

    Homework Statement The current loop of the radius b as shown in figure is mounted rigidly on the axle,midway between the two supporting cords.In the absence of the external magnetic field,the tension in the two cords are equal and are T.What will be the tension when a vertical magnetic field B...
  32. T

    Hall effect/Force on a current carrying wire

    Homework Statement A conducting rectangular solid of dimensions dx=5m dy=3m dz=2m moves at a constant velocity through a uniform magnetic field B=(30mT)j. What are the resulting a)electric field within the solid,in unit vector notation? b)potential difference across the solid? Homework...
  33. W

    Mathematica Is the integral for current correct?

    Hi, I am using Mathematica to calculate density of states and current of the Green's function times self energy in most simple form. I am not sure if I am getting current integral over energy implemented correctly. Shouldnt first current plot be a line with a slope? Below is my code...
  34. D

    Temperature related to Current flow on BBr or cables

    Temperature with hot spot by Ir thermal cameras of modern development is being used for measuring on the object of terminal surfaces and cable working temperatures in particular working loads. However, so far no measurements has been designed to obtain the result on the flow of current...
  35. giokrutoi

    Find Current Through Battery in Circuit: 3/11 or 21/19?

    Homework Statement the image of circuit is in attachment the question is to find the current through the battery Homework EquationsThe Attempt at a Solution I think that there is a y connection so above two and centered one form y from formula the whole resistance is 1 than I imagine bottomed...
  36. Mzzed

    Decaying current power calculation

    I would like to find the power loss over 0.3 seconds due to a resistance of 0.0015 ohms with a current following the function: I = e-15.24t-e-39984.75t where t is time. I would have imagined summing all the current over that 0.3 second period via integration would then allow me to find...
  37. T

    Hall effect/force on current carrying wire

    Homework Statement A metal strip 8.5cm long,0.65 cm wide,0.76 mm thick moves with constant velocity v through a uniform magnetic field B=0.2mT directed perpendicular to the strip,as shown in figure.A potential difference of 3.9 microV is measured between points x and y across the...
  38. an_single_egg

    Is a moving magnet the only way to induce a current?

    Homework Statement My class was watching a video on electricity and magnetism, and after showing how current is induced in a loop of wire when a magnet moves through it, our teacher asked us if there is another way to induce current in a loop of wire - he told us that there were in fact two...
  39. P

    Voltage and current phase shifting/Current without voltage?

    Hello, I've recently been learning about capacitance and inductance causing the current to lead or lag. But how can the current possibly maintain the same waveform? Shouldn't the zeros of voltage and current always align? How can there be current without voltage?
  40. S

    Website for current El Nino - La Nina conditions?

    Is there website that shows recent El Nino -vs-La Nina conditions in concise form? - or is the intensity of El Nino too vague a concept to quantify?
  41. J

    Capacitor - why does current flow

    I have question, why can condesator get charged, when connected to voltage source, if for current to flow, there most be closed wire, but here it is not, but there still is current? Thanx for answers.
  42. G

    Current flow on the surface of a permeability bigger than 1

    Hi, Quick description of the problem at hand: spherical perfect conductor around the origin with radius a, spherical shell (with radius b) around it made of a material with given magnetic permeability bigger than 1. Uniform Magnetic field in the area. The solution I am looking at (which I won't...
  43. bachir1994

    Neutral current in three-phase systems

    Hello, In three-phase systems, star coupling for example, and in the case where single-phase sources are supplied using the three phases L1, L2 and L3 with a common neutral return, My first question is: when one is balanced il1 = il2 = Il3 is what the current flowing in the neutral is...
  44. bachir1994

    Current and voltage relationship in an electric motor

    Hello, I can not understand that a motor (pumping) requires a current of 63 A under a voltage of 390 vac, and requires a current of 72 A under a voltage of 365 vac. Normally when the voltage increases the current increases with (ohm law). Is that the power delivered by the engine which is 37 kw...
  45. Berg88

    Fan Current to Speed (Percentage)

    Hi All, I have a VFD running supply fans and I currently have two values I can see. One is the VFD actual speed percentage from the VFD. The other is a calculated Fan Speed based off of VFD current. (I control off the calculation). The calculation is (Current^.33)*25.54=%. Does anyone know this...
  46. A

    Why is the electric field inside the dielectric cancelling?

    So, I was studying force between the plates of a capacitor when a dielectric is inserted. Here is my question https://ibb.co/cenvXk Shouldn't it be like this picture below https://ibb.co/kOUsCk So, why is my teacher saying that the electric field inside the dielectric cancelling. So, what...
  47. T

    Displacement current in coaxial cables

    To calculate the displacement current in a coaxial cable (with equal and opposite currents on the inner and outer conductors), most standard texts use the magnetoquasistatic approximation, which ignores the time-varying electric field term in Ampere’s Law. Using this approximation, the...
  48. Muthumanimaran

    Finding the maximum value of current

    Homework Statement galvanometer with 50 divisions on the scale requires a current sensitivity of 0.1 m A/division. The resistance of the galvanometer is 40Ω. If a shunt resistance 0.1 Ω is connected across it, find the maximum value of the current that can be measured using this ammeter...
  49. D

    Problem regarding periodic current functions

    Homework Statement Three periodic currents have the same ##f=100 Hz##. The amplitude of the second current is ##4 A##. and is equal to half of the amplitude of the third current. Effective value of the third current is 5 times that of the first current. At time ##t_1=2ms## third current...
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