What is Current calculation: Definition and 30 Discussions

In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point. In SI base units, the electric current density is measured in amperes per square metre.

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  1. PhysicsTest

    Engineering Voltage and current calculation of circuit

    I am trying to find voltages and currents of the below circuit, 3.3 -22000*I2 - 2200(I2-I3) = 0 3.3 -24200*I2 + 2200*I3 = 0 -> eq1 -(10 - I3)*1500 - (I2 - I3)*2200 = 0 -15000 + 1500*I3 - 2200*I2 + 2200*I3=0 -15000 - 2200*I2 + 3700*I3=0 -> eq2 Solving equations 1 and 2 i get I2=0.38 Amps...
  2. simphysics

    Current calculation of a Y-junction

    Hello everyone! I've been trying to solve this circuit but there's something wrong. Firstly, I made a Delta-Y conversion so that1 and zA were in series, and so were z5 and zb. I really don't know if writing "I0=IA-IB" is correct, cause basically I0 is the current that flows between the nodes A...
  3. Mathhhew

    Rated current of a common mode choke

    Hello! I've obtained common mode choke from detached pieces, so I don't know anything about them, exept for their inductance/resistance. I'd like to know how could I determine the rated current of these coilsthank you in advance for your help
  4. Shan43

    B How to find the current density in an alkaline electrolyzer?

    To my understanding, current density is simply the current flowing through the alkaline electrolyzer divided by the area (the units for current density are A/m^2). But what would the area be in this situation? Is it the area of the electrodes or maybe the area of the electrolyte solution or...
  5. M

    Engineering Kirchoff's Law Problem about this Induction Generator circuit

    Hi, Please find attached below the Induction Generator circuit. I have the following parameters: Parameter Value Rs = Rr (Resistance on stator and rotor) 0.2 Ω Ls = Lr (inductance on stator and rotor) 5 mH = 0.005 H p (number of pairs of poles) 2 f (frequency) 60 Hz Vsl (stator line...
  6. PhysicsTest

    Understanding Inductor Behavior When Transistors Are Off

    a. When the transistors are ON. ##V_{CC} = V_L## ##V_{CC} = L \frac{di_L} {dt} ## ##i_L = \frac{V_{CC}t} L ## b. I am bit confused when the transistor is "OFF" The point "A" is floating? The transistors and the diodes all the elements seem to be open is it correct? I am confused here.
  7. J

    How Do Kirchhoff's Laws Help Calculate I1, I2, and I3 in a Circuit?

    According to the circuit in the figure; Can you calculate the values of the currents I1, I2, and I3. Can you send me a detailed solution to understand?
  8. Yani Botsanovski

    Eddy current calculation question

    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...
  9. E

    Electric current and resistance question

    Homework Statement:: problem solving You build a wire by combining an 8 inches copper wire with a 10 inches nichrome wire. If their combine resistance is 10 kΩ, find the cross section area of both wires. The nichrome wire has twice the area of the copper wire. Homework Equations:: I = V/R...
  10. Ruskointhehizzy

    Need help finding current on RC circuit

    Homework Statement In the circuit shown in the figure each capacitor initially has a charge of magnitude 3.60nC on its plates. After the switch S is closed, what will be the current in the circuit at the instant that the capacitors have lost 80.0% of their initial stored energy? the shown 3...
  11. mheruian

    Understand the Current Consumption of an IC in its Datasheet

    << Mentor Note -- Thread moved to the EE forum >> Hi, I'm new here and maybe this is the best section where I could need help :) I've been interested in electronics lately (not schooling anymore, more on self-study, but I'm not that smart, just a dedicated one and i can't understand everything...
  12. Hamood97

    Find the two figures and the get value of the resistor and current

    Homework Statement finding the resistor and current which is following through the circuit[/B]Homework Equations kirchhoff law The Attempt at a Solution almost as fig 1 ( 9v=3.458 mA and 12v=11.122 mA) fig 2 (9v=1.472 mA and 12v=12.882 mA) i3=2.48 mA
  13. I

    How to find a current is this specific circuit

    Homework Statement Find the voltage Vo for this circuit. Given: is = 36 A Link to circuit: https://session.masteringengineering.com/problemAsset/1824621/4/pr_2-32.jpg Homework Equations V = IR Kirchhoff's laws for current and voltage.The Attempt at a Solution I first noticed that the...
  14. Umar Awan

    What is the reason for using high KVA transformers in electrical heaters?

    Note: I have a feeling this is below Electrical Engineering requirements, but I couldn't find a more suitable category, so I think I'll extort the advantages of a forum base with electrical understanding more than I think may be required(ofcoarse I know very little about the field, so I may fall...
  15. Z

    Proving an expression / help with defining electric current

    Homework Statement http://imgur.com/AotzH28 Two long, straight conducting wires with linear mass density λ are suspended from cords so that they are each horizontal, parallel to each other, and a distance d apart. The back ends of the wires are connected to each other by a slack,low-resistance...
  16. S

    What is the required current for maximum torque in a 33 kg cm servo motor?

    I have recently purchased this servo motor ,which has rated stall torque of 33 kg cm at 6V. Statical current :16 mA Stall Current: 3+0.6 AOur technical query is,in order to obtain the maximum torque..what current do we need to be able to supply it Is 16 mc sufficient..or we need 3.5A?
  17. M

    Maximum current carrying capacity of Bus Bar

    If I have to transfer 250 MWh through 3 phase aluminium tubular busbar what is the maximum current carrying capacity under normal condition at 80c temperature and voltage is 132kv at busbar from each 60mw 04 transformers 50hz 132/11kv stepup transformers connected on that busbar, this is not...
  18. sandeep agari

    Circuit Current: How to Calculate IA, IB, IC, ID

    hello, while making a circuit ( uploaded pic) ,the specifications of leds are 50mA/2V, i found the current ( ID )just before the leds to be around 180mA. i just want to know how to determine the currents in the circuit at various points( IA, IB , IC, ID). in general i want to know how to...
  19. V

    Calculate Current for 5V Sinusoidal Input Voltage

    I am doing an experiment where am giving 5 volts sinusoidal input voltage to a coil and receiving 1.5 volts in other coil how can i calculate current flowing through it..? if i take current as the ratio of input voltage to impedance of circuit will it be correct...?
  20. D

    Engineering RLC circuit - Differential equation - Stationary current calculation

    Homework Statement I'm decent with differential equations for RLC circuits, and I KNOW the stationary current will be zero, but I need help to work it out mathematically, because my maths gets me -2.4A (...) L: 0.05H C: 0.04F R: 3 Ω U (source) = 1 V I've got the transient solution: c1e-10t +...
  21. G

    Engineering Complex current calculation in Parallel R L Circuit

    Homework Statement I need to find the complex current in this circuit http://imageshack.us/photo/my-images/51/figure1j.jpg/ Homework Equations I calculated the inductor's impedance and found that impedance = 12.57 Ohms so I used it in the equation for the Current. I need to write the answer...
  22. L

    How Do You Calculate Current in Basic Circuit Problems?

    Homework Statement Required data provided on the http://futureislong.tumblr.com/image/35265986925Homework Equations Not requiredThe Attempt at a Solution I can easly calculate the voltage but no idea how to calculate current... Here is the image: Please help me calculate all the currents...
  23. O

    Engineering Conductor inside an electric motor current calculation

    Homework Statement A 500 mm conductor inside an electric motor has a force of 1.5 Newtons exerted on it. If it is at right angles to a magnetic field of flux density 0.6 T, calculate the current flowing in the conductor. Homework Equations F=B.I.L The Attempt at a Solution B = 0.6T F =...
  24. J

    3-Phase Circuit - Line Current Calculation Question

    Hello, While reviewing my professor's notes and my textbook I've run to a discrepancy in regard to how to calculate line current in a 3-phase circuit. In these particular examples, you are given a 3-phase balanced y-source connected to a y-load with equal impedance on each phase. In...
  25. I

    Drift current calculation drift verlocity not given

    Calculate drift current. length of wire 1m for 10V cross sectional area = 0.001m^2 e = 1.602 x 10^-19 ue = 3.18 x 10^-7 n = 10^23 electrons / m^3 what does ue stand for? how do i calculate drift verlocity? 3. The Attempt at a Solution i am using the formula I = nAVq where...
  26. Femme_physics

    Electronics current calculation

    Homework Statement http://img560.imageshack.us/img560/2759/theprob.jpg Calculate the direction and value of I1 going through R1 The Attempt at a Solution Can you let me know if this is correct? Seems to make sense to me. http://img220.imageshack.us/img220/8484/72041802.jpg
  27. I_am_learning

    What is the fault current calculation for a broken line touching a pole?

    Last time I was talking about Isolated Voltage, and some of you people were really helping me about, but I posted (did) something stupid and got the thread deleted. I am sorry for that. Now, I want to talk about my confusion in a different (safe) way. The above figure shows a...
  28. S

    Voltage and current calculation on a mixed circuit

    Homework Statement I have the following circuit http://informatici.vankeer.eu/files/2/Untitled.png R1 = 22 ohm, R2 = 39, R3 = 82, R4 = 100,R5 = 10 and V = 2volt I'm asked to calculate the voltage and current over de resistors when the switch is open and when the switch is closed...
  29. S

    3 Phase System Line to Ground fault Fault current calculation

    Six, 6.6kV ,3phase, alternators are connected to a common set of bus bars. Each has positive negative and zero sequence reactances of 0.90 ohm, 0.72 ohm, 0.30 ohms respectively . An Earth fault occurs on one bus bar . Determine the value of fault current if all alternator neutrals are solidly...
  30. I

    Current Calculation Problem (Probably Simple)

    A really basic circuit problem which I just don't understand. In the attached figure, C is a cell of e.m.f. 2V and internal resistance 1 Ohm. Calculate: a) the current through A b) the current through B c) the p.d. between the terminals of the cell I really don't understand how to calculate...