What is Current flow: Definition and 138 Discussions

An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving particles are called charge carriers, which may be one of several types of particles, depending on the conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or holes. In a electrolyte the charge carriers are ions, while in plasma, an ionized gas, they are ions and electrons.The SI unit of electric current is the ampere, or amp, which is the flow of electric charge across a surface at the rate of one coulomb per second. The ampere (symbol: A) is an SI base unit Electric current is measured using a device called an ammeter.Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ordinary conductors, they cause Joule heating, which creates light in incandescent light bulbs. Time-varying currents emit electromagnetic waves, which are used in telecommunications to broadcast information.

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  1. M

    No Current Flow with Negatively Charged Plate & Resistor

    If you had a negatively charged plate connected to a wire that had a resistor and on the other side of the resistor was a ground connection would electrons not flow? I tried this at home with one side of a battery and couldn't measure any current on my voltmeter.
  2. F

    Understanding Current Flow in Two Loops

    Homework Statement [PLAIN]http://img805.imageshack.us/img805/4889/adszsj.png in two loops at the top, when different currents float in different loops, can they change their current or , while one of them is increasing, is other one decreasing..? i could not decide if the question is so easy...
  3. G

    Circuit : Current Flow And Voltage Across Two Point

    Homework Statement Find Voltage across a and b and the missing current (i) so this is the circuit http://img3.imageshack.us/img3/184/circuitsf.jpg Homework Equations KCL and KVL current towards the node is + away is - Et = E1 + E2 + E3 in series Et = E1 = E2 = E3 in parallel Ohms law E= IR...
  4. N

    Is current flow not equal to electricity?

    Before i start my question , i have to mention that I'm only a beginner for physics and chemistry , if possible , please explain in the way that easier to be understand. In simple cell , 2 different metals are immersed in an electrolyte and connected to ammeter , the metal which is more...
  5. D

    Transformers: Uniform magnetic filed in relation to current flow

    Homework Statement In our lab about transformers we have a question as follows: Consider a loop in a uniform magnetic field. If the field is suddenly turned off, in which direction will the current flow in the wire? Homework Equations The Attempt at a Solution My first thought...
  6. F

    Current flow through no resistance conductor

    Homework Statement How does the electric current flow through this circuit? 2. The attempt at a solution It would make sense for me to take the path where there's no resistance and skip the path with the resistance R1, but I'm not 100% sure about that. So how does it flow? pic1 or pic2...
  7. Femme_physics

    Current flow quandary. Capacitors VS Resistors

    I know that in the left circuit, current will not flow where the resistors are attached to the straight wire connecting A and B, but on the right one, current will flow where the resistors are attached to the straight wire x and y http://img824.imageshack.us/img824/880/this1p.jpg Is...
  8. S

    Exploring AC Current Flow in Pure Inductors

    if a pure inductor is connected to an AC voltage source! The Back emf in the inductor=Thr instantaneous AC emf! THEN How can the current flow through the inductor if the NET VOLTAGE=0? please explain
  9. K

    Voltage difference, current flow

    Homework Statement A voltage difference is applied to a piece of copper wire, a 5.0 mA current flows. The copper wire is replaced with a silver wire with twice the diameter of the copper wire. A) How much current will flow through the silver wire? The lengths of both wires are the same, and...
  10. J

    Which situation will induce the greatest current flow?

    Homework Statement Question 30 from http://www.bced.gov.bc.ca/exams/search/grade12/english/release/exam/0708PH_p.pdf Homework Equations I really don't know but here are some that I think can be used: E=-N(flux)/t B=(permeability of free space)(n)I The Attempt at a Solution I...
  11. R

    Weird Current Flow in DC Circuit

    Edit: Nevermind, I figured it out! I jumped the gun in making this post. I'm doing another problem from Schaum's Outline: Basic Circuit Analysis. The problem, #3.24, and its solution are found in this...
  12. I

    Give magnitude and direction of current flow

    Homework Statement Problem 3 Homework Equations The Attempt at a Solution 1) Find I and voltage across resistor 5 V=IR 12.6 = I * 5.08 I=2.48 .08*2.48= .1984 12.6-.1984= 12.4 V across battery. So would I and V across the resistor be I=2.48 and V=12.4? 2) Find current I (Forgot to mark...
  13. D

    Thermodynamics: Exothermic & endothermic reaction in counter current flow

    Hi guys, I have a scenario here; let's say we have a exothermic reaction and a endothermic reaction going in co-current flow reactor (separated by a thin wall to facilitate heat transfer). At steady state after some time, from the concentration profile, we have the endothermic reaction going at...
  14. V

    Analysis of current flow and EM fields in seawater?

    Hi, I have a few queries regarding the flow of electric current through (sea)water... In general, can the flow of electricity through seawater be treated the same as through a metal conductor? I am wondering whether the fact that it is ions rather than electrons that carry the charge has...
  15. Z

    Need help setting up FEMM for current flow problem

    I am new to FEMM 4.2 and need help setting up a simple current flow problem. I have a square copper sheet that has input and output terminals (square contacts) in opposite corners and and 1000A flowing across it. The sheet is 16" square and the contacts are 2" square. The sheet is 0.050" and...
  16. U

    Absolute begginer's question (direction of current flow)

    So I've been trying to wrap my head around the concept of the direction of current flow. I thought a voltage divider would be a good place to start. One website I've visited told me that the following image is a voltage divider. Both R1 and R2 will work together to affect the voltage of...
  17. M

    Grounding Wire: Preventing Current Flow & Circuit Breakdowns

    What stops current from flowing through the grounding wire? How come it can flow through once another part of the circuit breaks?
  18. H

    How does current flow in an antenna?

    Let's say we have a dipole antenna that we are using to radiate a signal. The dipole antenna (think rabbit ears) has two ends that appear to me to be open circuits. Maybe my problem is that I have too much circuit background and not enough EM, but how does current flow through these rabbit...
  19. S

    What makes current flow in a transmission line?

    In a transmission line, what makes the current flow? I understand that the line is excited by an AC voltage at one end. This sets up a changing electric field between the conductors and therefore a changing magnetic field. However, there is no voltage along the line, so what makes the current...
  20. S

    Probability of current flow through circuit

    The probability of the closing of the ith relay in the circuits shown is given by p_i. Let p_1 = 0.9, p_2 = 0.6, p_3 = 0.1, p_4 = 0.7, p_5 = 0.2. If all relays function independently. what is the probability that a current flows between A and B for the respective circuits...
  21. B

    Magnetic Field and Current Flow: Explained

    Homework Statement Hello: I have the following: The component of the magnetic field parallel to a plane of sheet is the same magnitude on both sides, but changed direction by \frac{1}{2}\pi in going through the sheet. I am supposed to explain what is going on. So B were to change...
  22. I

    Question on current flow through polarized capacitors

    If a current enters the negative terminal of a polarized capacitors, does the negative plate have to be fully charged before it passes through to the positive plate.
  23. L

    Measuring Current Flow in Open Circuit R Phase

    how do i measure the current flow threw the neutral wire if phase R is open circuited? the impedance per load is 3+7j
  24. M

    Will the battery current flow correctly?

    I am designing my own rocket. In order to launch a series of rockets in midair, an electric current must flow to the rocket engines. To be able to do this, I have sketched the design included below. Above, are the three rockets which will be ignited. The metal ends on the bottom of the...
  25. A

    Electric current flow in a circuit when a capacitor is fully charged?

    Why doesn't electric current flow in a circuit when a capacitor is fully charged? I mean there is still the battery making the E field, why is it unable to move the electrons of the wire of the circuit?
  26. F

    How can current flow in A/C circuits?

    How can current flow in A/C circuits!? Hello everyone! In alternating current circuits, such as the North American main power grid, voltage swings from 120V to -120V at a rate of 50-60 cycles per second, right? If that's true, than how can current ever reach the load?? It seems like the...
  27. T

    Engineering Finding Current Flow in a Circuit: KCL Solutions

    Ok So how do i find the current going through here. I understand the whole tope a node, and bottom is. How would i set it up using KCL. I struggle with the problems were current is just given no voltage. Can someone please help If its hard to see picture the 6A is to far left then going...
  28. B

    Can Adjacent Coils in a Solenoid Touch Without Affecting Its Functionality?

    To create a solenoid, conductive wire is coiled with n # of turns per unit length. To create a real solenoid can each coil touch the adjacent coil or does there have to be some non-conductive material between them? The reason I ask is it seems if they were touching that current would flow...
  29. C

    Variance of resistance with significant current flow

    The value of a real-world resistor ( ) changes with significant time as the resistor conducts a current. Answer choices Never Rarely Sometimes Usually Always Explain why.
  30. E

    What is the Direction of Current Flow in a Parallel Conducting Wire?

    Homework Statement There an electron and its moving parallel to and above a horizontal conducting wire. When A current is allowed to pass through the wire the electron is seen to move towards the wire. The direction of current flow is...Homework Equations None/hand thumb rule The Attempt at...
  31. rohanprabhu

    Questioning of fundamentals of current flow

    Although i do understand how current is same in electrical components in series.. but why does the voltage remain constant in parallel? Also since voltage remains constant in parallel, is that the reason change in voltage is generally chosen as the signal in digital circuits?
  32. S

    Does Electron Flow Reverse the Conventional Current Direction?

    Homework Statement I'm much too confused about direction of flow of current.Conventionally, it's said that flow of charge is due to +ve charge carriers & high potential end of battery being +ve & low potential end being -ve,current flow will be from positive(high) to negative (low)...
  33. M

    Analyzing Conditions for Current Flow Through Resistor R

    Homework Statement The drawing shows a wire loop near a current -carrying wire. Under what conditions would current flow through resistor R from Right to left? Homework Equations Lenz's law The Attempt at a Solution 4 answers a) when the current I is increasing b)when the...
  34. K

    Which Diagram Shows Accurate Current Flow?

    Homework Statement There are 4 diagrams for this questions. Which one do you think it's true? (The diagram has a battery with a lightbulb attached to it) Homework Equations N/A The Attempt at a Solution I think that the current flows from one end to other end but not sure if the...
  35. F

    How Does Time Affect Current Flow?

    Hi, I want to ask a qusetion about the electrons, what the time plays with the current flow? what will be happen for example with current 0.5A in the wire with 5 ohm? thx
  36. B

    Rail Guns: Dual Rods & Current Flow

    Ok, so we learned about rail guns today (they are so freakin' cool), and I understand how it moves one rod down the rails... however, what happens if there are two? Won't both move down the rails (away from battery) since the current is flowing clockwise, or will they repel each other?
  37. P

    T vs MOSFET: Which one is better for current flow control?

    Current flow in a generator?? In an AC generator what are 2 things that are going to determine the current flow (or the direction of I)?
  38. T

    How does current flow through a capacitor?

    this is a fundamental thing that has been bothering me does current even flow through a capacitor at all?? the plates are separated right, so I would think no I can imagine the electrons coming out of the battery and collecting on the capacitor plate, and pushing the ones on the other side...
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