Electric current Definition and 18 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. V

    Do electrons flow through a battery or is it something else?

    This is a confusing question. I am not sure if electrons flow through the battery from positive terminal to negative terminal against the electric field within the battery; or the electrons deposit on positive plate resulting in a chemical reaction that releases electrons at the negative plate...
  2. fluidistic

    I Energy flux direction in a conducting wire?

    On the Internet, I have read that the energy doesn't flow in the wire, for example in a very simple electric circuit made of a battery and a closed loop. When one computes the Poynting vector ##\vec S \propto \vec E \times \vec B##, one gets that its direction is towards the center of the wire...
  3. A

    Finding a good descriptive model of the electric circuit (for 8th graders)

    Since this quesstion popped up in this thread I thought it might be better to create a new thread: https://www.physicsforums.com/threads/a-question-about-an-electrons-movement-in-a-dc-circuit.997736/ The question is the following: What kind of descriptive model could/should one use while first...
  4. J

    Electric current calculation

    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?
  5. Adesh

    How can electrons flow all the way through the circuit?

    Electric currents and the things within are generally explained through the help of intuitive water current examples, where potential difference is explained through the pressure difference and electric current is explained as the flow of water. But I like to think in terms of some driving force...
  6. Shivang kohlii

    Why is resistance of similar cases calculated differently?

    Homework Statement 1.In the WE-11 resistance is calculated by integrating and that too by taking length as dr and area as the CSA of the small cylinder .. Shouldn't length be l and area by 2πrdr..? I also don't understand why can't we simply use Dl/A formula , Where A =π((2R)^2 - R^2) 2)...
  7. P

    I Why is displacement current excluded from the four-current?

    To put this in another way, is there some reason from first-principles as to why we have j as the spatial component of the four-current rather than the total current density which includes the displacement current? Has anyone tried to see what the experimental consequences of this would be...
  8. C

    Symmetry in Electrical Circuit Analysis

    How is symmetry used to solve electrical circuits? I have seen several problems in books in which currents in two resistors are said to be equal due to 'symmetry'. That is a concept that I fail to understand and thus cannot apply. In class, we were shown a few circuit diagrams which were...
  9. H

    Find the current I in this electrical circuit

    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
  10. hackhard

    Conductivity of an electrolyte

    I know that electric conductivity of metallic conductors increases with decrease in its absolute temperature(kelvin) . But is it the same for electrolytes such as water. Is cold water a better or worse conductor of electricity than warm water at same pressure and concentration.
  11. 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...
  12. F

    Calculate resistance if the switch is closed 2 battery with different voltage

    Homework Statement before that, can you tell me about "current flow in this circuit" if : A. the switch is open B. the switch is closed the Question is No. 1 Calculate the resistance of R if the value of the current I in the figure is 0.50 A. ( i think it is related to no 2) no 2...
  13. F

    I Show me how terms with Q disappear

    The general Ampere force law equation given by Maxwell is: According to Maxwell, all terms containing function ##Q(r)## will vanish after closed integration w.r.t. ##s'## because they will get reduced to functions of ##r## and the upper and lower integration limits will be same since the...
  14. S

    AC Current in GHz Frequency and Zero Resistance

    Hello Experts, I am a physics newbie with big ideas. I have a question. I am thinking about how to produce a zero Resistance Current. We know we can do this using super-conductors in sub zero temperature, but maybe there's another way. My assumptions (which could be wrong): 1) Resistance in a...
  15. donaldparida

    Will any charge flow through the circuit?

    https://drive.google.com/open?id=0B3IenBvKWb4PZW9rRWg4cXptT2c I had to find the resistance of this circuit between A and B. My teacher said that since the blank wires have zero resistance, the potential difference across the ends of the blank wire is zero(according to v = ir) and thus 1,4 are...
  16. G

    220V 50Hz Equipment vs. 230V 60Hz Equipment compressor

    If If you have a compressor designed for US 60 HZ 230 V what are the risks with applying it in 220 V 50 HZ ? I understand there will be a ~20% derate in power but are there any safety or failure concerns ? would the lifespan of equipment change? Do I need a transformer ? This equipment...
  17. V

    Some questions on terminology (for native English speakers)

    Hello! I am a beginner in English terminology. I know that direct current is a flow of electricity that moves in one direction only (i.e. does not change its direction). I also know that alternating current is an electric current that reverses direction at regular intervals. However, I cannot...
  18. P

    How is electrical current delivered into houses?

    How is the potential difference done? How do they make electrons move? Do they use electrical field using positive (to atract them) or negative charges (to repel them)? Do they use variables magnetic fields?