What *exactly* is electrical current, voltage, and resistance?












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$begingroup$


I am taking AP Physics right now (I'm a high school student) and we are learning about circuits, current, resistance, voltage, Ohm's Law, etc. I am looking for exact definitions of what current, voltage, and resistance are.



My teacher, as I'm sure most physics teachers do, compared a wire with current flowing through it to a pipe with water flowing through it. The thinner the pipe, the more 'resistance'. The more water pressure, the more 'voltage'. And the faster the water travels, the higher the 'current'.



I took these somewhat literally, and assumed that current is literally the velocity of electrons, voltage is the pressure, etc. My physics teacher said that the analogy to the water pipe is only really used for illustrative purposes. I'm trying to figure out exactly what current, resistance, and voltage are, because I can't really work with a vague analogy that kind of applies and kind of doesn't.



I did some research, and found this page which provided a decent explanation, but I was slightly lost in the explanation given.



Let me know if this question has already been asked (again, remember: I don't want an analogy, I want a concrete definition).










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    1












    $begingroup$


    I am taking AP Physics right now (I'm a high school student) and we are learning about circuits, current, resistance, voltage, Ohm's Law, etc. I am looking for exact definitions of what current, voltage, and resistance are.



    My teacher, as I'm sure most physics teachers do, compared a wire with current flowing through it to a pipe with water flowing through it. The thinner the pipe, the more 'resistance'. The more water pressure, the more 'voltage'. And the faster the water travels, the higher the 'current'.



    I took these somewhat literally, and assumed that current is literally the velocity of electrons, voltage is the pressure, etc. My physics teacher said that the analogy to the water pipe is only really used for illustrative purposes. I'm trying to figure out exactly what current, resistance, and voltage are, because I can't really work with a vague analogy that kind of applies and kind of doesn't.



    I did some research, and found this page which provided a decent explanation, but I was slightly lost in the explanation given.



    Let me know if this question has already been asked (again, remember: I don't want an analogy, I want a concrete definition).










    share|cite|improve this question









    New contributor




    Addison is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.







    $endgroup$















      1












      1








      1





      $begingroup$


      I am taking AP Physics right now (I'm a high school student) and we are learning about circuits, current, resistance, voltage, Ohm's Law, etc. I am looking for exact definitions of what current, voltage, and resistance are.



      My teacher, as I'm sure most physics teachers do, compared a wire with current flowing through it to a pipe with water flowing through it. The thinner the pipe, the more 'resistance'. The more water pressure, the more 'voltage'. And the faster the water travels, the higher the 'current'.



      I took these somewhat literally, and assumed that current is literally the velocity of electrons, voltage is the pressure, etc. My physics teacher said that the analogy to the water pipe is only really used for illustrative purposes. I'm trying to figure out exactly what current, resistance, and voltage are, because I can't really work with a vague analogy that kind of applies and kind of doesn't.



      I did some research, and found this page which provided a decent explanation, but I was slightly lost in the explanation given.



      Let me know if this question has already been asked (again, remember: I don't want an analogy, I want a concrete definition).










      share|cite|improve this question









      New contributor




      Addison is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      $endgroup$




      I am taking AP Physics right now (I'm a high school student) and we are learning about circuits, current, resistance, voltage, Ohm's Law, etc. I am looking for exact definitions of what current, voltage, and resistance are.



      My teacher, as I'm sure most physics teachers do, compared a wire with current flowing through it to a pipe with water flowing through it. The thinner the pipe, the more 'resistance'. The more water pressure, the more 'voltage'. And the faster the water travels, the higher the 'current'.



      I took these somewhat literally, and assumed that current is literally the velocity of electrons, voltage is the pressure, etc. My physics teacher said that the analogy to the water pipe is only really used for illustrative purposes. I'm trying to figure out exactly what current, resistance, and voltage are, because I can't really work with a vague analogy that kind of applies and kind of doesn't.



      I did some research, and found this page which provided a decent explanation, but I was slightly lost in the explanation given.



      Let me know if this question has already been asked (again, remember: I don't want an analogy, I want a concrete definition).







      electric-circuits electric-current electrical-resistance voltage






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      Addison is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      share|cite|improve this question









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      edited 1 hour ago









      Qmechanic

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      asked 4 hours ago









      AddisonAddison

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      91




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      New contributor





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          4 Answers
          4






          active

          oldest

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          2












          $begingroup$

          In terms of circuits...



          Current is the rate at which charge flows past a point in a circuit.



          $$I=frac{dQ}{dt}$$



          The voltage between two points in a circuit is the negative of the line integral of the electric field along the circuit between those two points.



          $$Delta V_{AB}=-int_A^B mathbf{E}cdot dell$$



          The resistance of a segment of the circuit is the ratio of the voltage across that segment to the current through that segment.



          $$R=frac{V}{I}$$






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            For Current, what is charge? Can I interchange it with electrons? That is, can I say "Current is the rate at which electrons flow along a wire"? For voltage, I don't know any multivariable calculus, is there any explanation that uses just basic calculus, or some other operation? For resistance, I suppose that makes sense
            $endgroup$
            – Addison
            4 hours ago






          • 2




            $begingroup$
            Charge is what produces electric field. Electrons and protons have charge. In a circuit, electrons move and protons do not. Every electron has the same amount of charge. Therefore the current is the number of electrons per second passing a point in the circuit, times the charge on each electron.
            $endgroup$
            – G. Smith
            3 hours ago






          • 1




            $begingroup$
            There is nothing multivariable about a line integral. It is a one-dimensional integral, along the circuit.
            $endgroup$
            – G. Smith
            3 hours ago












          • $begingroup$
            There is a sign error in the equation for voltage. Your rhs gives $V_{BA}$ ($V_B-V_A$), not $V_{AB}$.
            $endgroup$
            – The Photon
            15 mins ago





















          2












          $begingroup$

          Before explaining current, we need to know what charge is, since current is the rate of flow of charge.



          Charge is measured in coulombs. Each coulomb IS a large group of electrons, 1.6x10^19 of them to be more exact.



          The “rate of flow” of coulombs/charge is simply charge/time and this calculation for a circuit give you the number of coulombs that went past a point in a second This is just what current is.



          Resistance is a circuit’s resistance to current, it is like you said measured in ohms, but it is caused by the vibrations of atoms in a circuits wire and components, which results in collisions with electrons, making charge passage difficult. This increases with an increase in temperature of the circuit, as the atoms of the circuit have more kinetic energy to vibrate with



          Voltage is the energy in joules per coulomb of electrons. This is shown though the equation E=QV where the ratio of Energy over charge= voltage. This is granted by the battery, which pushes coulombs of electrons, with what we call electromotive force. However when it is said that the potential difference across a component is X volts, it means that each coulomb is giving X that much energy.



          Note: if an equation doesn’t make intuitive sense to you, chances are it is a complicated derivation, and to understand it you’ll have to learn it’s derivation






          share|cite|improve this answer











          $endgroup$





















            0












            $begingroup$

            Voltage:



            This is the electrical potential energy difference. It's the difference in electric potential between two points. Which is a measure of how much energy it takes to move a test charge between the two points.



            Current:



            This is literally a measure of how much electric charge is currently being pushed past a point or region. A current is produced by introducing charge to a voltage. Note, that I use "electric charge" instead of "electrons" because any difference in voltage will result in current flow. For instance, electrochemical cells deliver current through molecular ions. Batteries fall in this category.



            Resistance:



            This is the measure of the opposition to current flow. Every wire has some resistance, however you want specific resistor materials to meaningfully resist current flow. It's affected by cross section, and the material used to make it.






            share|cite|improve this answer








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            • 1




              $begingroup$
              This explanation of voltage is confusing because it does not explain the distinction between potential energy and potential. And it does not hold when the electric field is induced by a changing magnetic field and is therefore non-conservative.
              $endgroup$
              – G. Smith
              3 hours ago





















            0












            $begingroup$

            This is not a complete answer, but a bit too much for just a comment. I want to just address a couple of points in your question.



            When you say "current is the velocity of electrons", you're half right. Current measures the total quantity of charge moving through a surface (for example, a cross-section of a wire) per unit time. It could increase if the velocity of the carriers increases, or if there's simply more carriers present moving the same speed. And the carriers could be electrons, or they could be protons (for example, in an ionic solution or a wet cell), or they could be electron holes, but explaining that is probably getting beyond what you need to learn right now.



            When we say "voltage is like pressure", there we really are making a very loose analogy. Differences in voltage are what exert forces on charge carriers, so differences in voltage are what cause current to flow. In the same way differences in pressure are what cause water to flow in a pipe. But that's where the analogy ends. You shouldn't read anything into it about what creates differences in voltage, how voltage might be distributed in a wire, etc.



            You should also realize that voltage is not really fundamental. In electrostatics, it's just a way of summarizing the effects of electric fields (as pointed out in another answer, electrostatic voltage is just the integral of electric field along a path). More generally, it can also be produced by changing magnetic fields. But really it's the electric field that actually produces a force on charged particles, not the voltage per se.






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              4 Answers
              4






              active

              oldest

              votes








              4 Answers
              4






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              2












              $begingroup$

              In terms of circuits...



              Current is the rate at which charge flows past a point in a circuit.



              $$I=frac{dQ}{dt}$$



              The voltage between two points in a circuit is the negative of the line integral of the electric field along the circuit between those two points.



              $$Delta V_{AB}=-int_A^B mathbf{E}cdot dell$$



              The resistance of a segment of the circuit is the ratio of the voltage across that segment to the current through that segment.



              $$R=frac{V}{I}$$






              share|cite|improve this answer











              $endgroup$













              • $begingroup$
                For Current, what is charge? Can I interchange it with electrons? That is, can I say "Current is the rate at which electrons flow along a wire"? For voltage, I don't know any multivariable calculus, is there any explanation that uses just basic calculus, or some other operation? For resistance, I suppose that makes sense
                $endgroup$
                – Addison
                4 hours ago






              • 2




                $begingroup$
                Charge is what produces electric field. Electrons and protons have charge. In a circuit, electrons move and protons do not. Every electron has the same amount of charge. Therefore the current is the number of electrons per second passing a point in the circuit, times the charge on each electron.
                $endgroup$
                – G. Smith
                3 hours ago






              • 1




                $begingroup$
                There is nothing multivariable about a line integral. It is a one-dimensional integral, along the circuit.
                $endgroup$
                – G. Smith
                3 hours ago












              • $begingroup$
                There is a sign error in the equation for voltage. Your rhs gives $V_{BA}$ ($V_B-V_A$), not $V_{AB}$.
                $endgroup$
                – The Photon
                15 mins ago


















              2












              $begingroup$

              In terms of circuits...



              Current is the rate at which charge flows past a point in a circuit.



              $$I=frac{dQ}{dt}$$



              The voltage between two points in a circuit is the negative of the line integral of the electric field along the circuit between those two points.



              $$Delta V_{AB}=-int_A^B mathbf{E}cdot dell$$



              The resistance of a segment of the circuit is the ratio of the voltage across that segment to the current through that segment.



              $$R=frac{V}{I}$$






              share|cite|improve this answer











              $endgroup$













              • $begingroup$
                For Current, what is charge? Can I interchange it with electrons? That is, can I say "Current is the rate at which electrons flow along a wire"? For voltage, I don't know any multivariable calculus, is there any explanation that uses just basic calculus, or some other operation? For resistance, I suppose that makes sense
                $endgroup$
                – Addison
                4 hours ago






              • 2




                $begingroup$
                Charge is what produces electric field. Electrons and protons have charge. In a circuit, electrons move and protons do not. Every electron has the same amount of charge. Therefore the current is the number of electrons per second passing a point in the circuit, times the charge on each electron.
                $endgroup$
                – G. Smith
                3 hours ago






              • 1




                $begingroup$
                There is nothing multivariable about a line integral. It is a one-dimensional integral, along the circuit.
                $endgroup$
                – G. Smith
                3 hours ago












              • $begingroup$
                There is a sign error in the equation for voltage. Your rhs gives $V_{BA}$ ($V_B-V_A$), not $V_{AB}$.
                $endgroup$
                – The Photon
                15 mins ago
















              2












              2








              2





              $begingroup$

              In terms of circuits...



              Current is the rate at which charge flows past a point in a circuit.



              $$I=frac{dQ}{dt}$$



              The voltage between two points in a circuit is the negative of the line integral of the electric field along the circuit between those two points.



              $$Delta V_{AB}=-int_A^B mathbf{E}cdot dell$$



              The resistance of a segment of the circuit is the ratio of the voltage across that segment to the current through that segment.



              $$R=frac{V}{I}$$






              share|cite|improve this answer











              $endgroup$



              In terms of circuits...



              Current is the rate at which charge flows past a point in a circuit.



              $$I=frac{dQ}{dt}$$



              The voltage between two points in a circuit is the negative of the line integral of the electric field along the circuit between those two points.



              $$Delta V_{AB}=-int_A^B mathbf{E}cdot dell$$



              The resistance of a segment of the circuit is the ratio of the voltage across that segment to the current through that segment.



              $$R=frac{V}{I}$$







              share|cite|improve this answer














              share|cite|improve this answer



              share|cite|improve this answer








              edited 3 hours ago

























              answered 4 hours ago









              G. SmithG. Smith

              11k11432




              11k11432












              • $begingroup$
                For Current, what is charge? Can I interchange it with electrons? That is, can I say "Current is the rate at which electrons flow along a wire"? For voltage, I don't know any multivariable calculus, is there any explanation that uses just basic calculus, or some other operation? For resistance, I suppose that makes sense
                $endgroup$
                – Addison
                4 hours ago






              • 2




                $begingroup$
                Charge is what produces electric field. Electrons and protons have charge. In a circuit, electrons move and protons do not. Every electron has the same amount of charge. Therefore the current is the number of electrons per second passing a point in the circuit, times the charge on each electron.
                $endgroup$
                – G. Smith
                3 hours ago






              • 1




                $begingroup$
                There is nothing multivariable about a line integral. It is a one-dimensional integral, along the circuit.
                $endgroup$
                – G. Smith
                3 hours ago












              • $begingroup$
                There is a sign error in the equation for voltage. Your rhs gives $V_{BA}$ ($V_B-V_A$), not $V_{AB}$.
                $endgroup$
                – The Photon
                15 mins ago




















              • $begingroup$
                For Current, what is charge? Can I interchange it with electrons? That is, can I say "Current is the rate at which electrons flow along a wire"? For voltage, I don't know any multivariable calculus, is there any explanation that uses just basic calculus, or some other operation? For resistance, I suppose that makes sense
                $endgroup$
                – Addison
                4 hours ago






              • 2




                $begingroup$
                Charge is what produces electric field. Electrons and protons have charge. In a circuit, electrons move and protons do not. Every electron has the same amount of charge. Therefore the current is the number of electrons per second passing a point in the circuit, times the charge on each electron.
                $endgroup$
                – G. Smith
                3 hours ago






              • 1




                $begingroup$
                There is nothing multivariable about a line integral. It is a one-dimensional integral, along the circuit.
                $endgroup$
                – G. Smith
                3 hours ago












              • $begingroup$
                There is a sign error in the equation for voltage. Your rhs gives $V_{BA}$ ($V_B-V_A$), not $V_{AB}$.
                $endgroup$
                – The Photon
                15 mins ago


















              $begingroup$
              For Current, what is charge? Can I interchange it with electrons? That is, can I say "Current is the rate at which electrons flow along a wire"? For voltage, I don't know any multivariable calculus, is there any explanation that uses just basic calculus, or some other operation? For resistance, I suppose that makes sense
              $endgroup$
              – Addison
              4 hours ago




              $begingroup$
              For Current, what is charge? Can I interchange it with electrons? That is, can I say "Current is the rate at which electrons flow along a wire"? For voltage, I don't know any multivariable calculus, is there any explanation that uses just basic calculus, or some other operation? For resistance, I suppose that makes sense
              $endgroup$
              – Addison
              4 hours ago




              2




              2




              $begingroup$
              Charge is what produces electric field. Electrons and protons have charge. In a circuit, electrons move and protons do not. Every electron has the same amount of charge. Therefore the current is the number of electrons per second passing a point in the circuit, times the charge on each electron.
              $endgroup$
              – G. Smith
              3 hours ago




              $begingroup$
              Charge is what produces electric field. Electrons and protons have charge. In a circuit, electrons move and protons do not. Every electron has the same amount of charge. Therefore the current is the number of electrons per second passing a point in the circuit, times the charge on each electron.
              $endgroup$
              – G. Smith
              3 hours ago




              1




              1




              $begingroup$
              There is nothing multivariable about a line integral. It is a one-dimensional integral, along the circuit.
              $endgroup$
              – G. Smith
              3 hours ago






              $begingroup$
              There is nothing multivariable about a line integral. It is a one-dimensional integral, along the circuit.
              $endgroup$
              – G. Smith
              3 hours ago














              $begingroup$
              There is a sign error in the equation for voltage. Your rhs gives $V_{BA}$ ($V_B-V_A$), not $V_{AB}$.
              $endgroup$
              – The Photon
              15 mins ago






              $begingroup$
              There is a sign error in the equation for voltage. Your rhs gives $V_{BA}$ ($V_B-V_A$), not $V_{AB}$.
              $endgroup$
              – The Photon
              15 mins ago













              2












              $begingroup$

              Before explaining current, we need to know what charge is, since current is the rate of flow of charge.



              Charge is measured in coulombs. Each coulomb IS a large group of electrons, 1.6x10^19 of them to be more exact.



              The “rate of flow” of coulombs/charge is simply charge/time and this calculation for a circuit give you the number of coulombs that went past a point in a second This is just what current is.



              Resistance is a circuit’s resistance to current, it is like you said measured in ohms, but it is caused by the vibrations of atoms in a circuits wire and components, which results in collisions with electrons, making charge passage difficult. This increases with an increase in temperature of the circuit, as the atoms of the circuit have more kinetic energy to vibrate with



              Voltage is the energy in joules per coulomb of electrons. This is shown though the equation E=QV where the ratio of Energy over charge= voltage. This is granted by the battery, which pushes coulombs of electrons, with what we call electromotive force. However when it is said that the potential difference across a component is X volts, it means that each coulomb is giving X that much energy.



              Note: if an equation doesn’t make intuitive sense to you, chances are it is a complicated derivation, and to understand it you’ll have to learn it’s derivation






              share|cite|improve this answer











              $endgroup$


















                2












                $begingroup$

                Before explaining current, we need to know what charge is, since current is the rate of flow of charge.



                Charge is measured in coulombs. Each coulomb IS a large group of electrons, 1.6x10^19 of them to be more exact.



                The “rate of flow” of coulombs/charge is simply charge/time and this calculation for a circuit give you the number of coulombs that went past a point in a second This is just what current is.



                Resistance is a circuit’s resistance to current, it is like you said measured in ohms, but it is caused by the vibrations of atoms in a circuits wire and components, which results in collisions with electrons, making charge passage difficult. This increases with an increase in temperature of the circuit, as the atoms of the circuit have more kinetic energy to vibrate with



                Voltage is the energy in joules per coulomb of electrons. This is shown though the equation E=QV where the ratio of Energy over charge= voltage. This is granted by the battery, which pushes coulombs of electrons, with what we call electromotive force. However when it is said that the potential difference across a component is X volts, it means that each coulomb is giving X that much energy.



                Note: if an equation doesn’t make intuitive sense to you, chances are it is a complicated derivation, and to understand it you’ll have to learn it’s derivation






                share|cite|improve this answer











                $endgroup$
















                  2












                  2








                  2





                  $begingroup$

                  Before explaining current, we need to know what charge is, since current is the rate of flow of charge.



                  Charge is measured in coulombs. Each coulomb IS a large group of electrons, 1.6x10^19 of them to be more exact.



                  The “rate of flow” of coulombs/charge is simply charge/time and this calculation for a circuit give you the number of coulombs that went past a point in a second This is just what current is.



                  Resistance is a circuit’s resistance to current, it is like you said measured in ohms, but it is caused by the vibrations of atoms in a circuits wire and components, which results in collisions with electrons, making charge passage difficult. This increases with an increase in temperature of the circuit, as the atoms of the circuit have more kinetic energy to vibrate with



                  Voltage is the energy in joules per coulomb of electrons. This is shown though the equation E=QV where the ratio of Energy over charge= voltage. This is granted by the battery, which pushes coulombs of electrons, with what we call electromotive force. However when it is said that the potential difference across a component is X volts, it means that each coulomb is giving X that much energy.



                  Note: if an equation doesn’t make intuitive sense to you, chances are it is a complicated derivation, and to understand it you’ll have to learn it’s derivation






                  share|cite|improve this answer











                  $endgroup$



                  Before explaining current, we need to know what charge is, since current is the rate of flow of charge.



                  Charge is measured in coulombs. Each coulomb IS a large group of electrons, 1.6x10^19 of them to be more exact.



                  The “rate of flow” of coulombs/charge is simply charge/time and this calculation for a circuit give you the number of coulombs that went past a point in a second This is just what current is.



                  Resistance is a circuit’s resistance to current, it is like you said measured in ohms, but it is caused by the vibrations of atoms in a circuits wire and components, which results in collisions with electrons, making charge passage difficult. This increases with an increase in temperature of the circuit, as the atoms of the circuit have more kinetic energy to vibrate with



                  Voltage is the energy in joules per coulomb of electrons. This is shown though the equation E=QV where the ratio of Energy over charge= voltage. This is granted by the battery, which pushes coulombs of electrons, with what we call electromotive force. However when it is said that the potential difference across a component is X volts, it means that each coulomb is giving X that much energy.



                  Note: if an equation doesn’t make intuitive sense to you, chances are it is a complicated derivation, and to understand it you’ll have to learn it’s derivation







                  share|cite|improve this answer














                  share|cite|improve this answer



                  share|cite|improve this answer








                  edited 3 hours ago

























                  answered 3 hours ago









                  Ubaid HassanUbaid Hassan

                  40216




                  40216























                      0












                      $begingroup$

                      Voltage:



                      This is the electrical potential energy difference. It's the difference in electric potential between two points. Which is a measure of how much energy it takes to move a test charge between the two points.



                      Current:



                      This is literally a measure of how much electric charge is currently being pushed past a point or region. A current is produced by introducing charge to a voltage. Note, that I use "electric charge" instead of "electrons" because any difference in voltage will result in current flow. For instance, electrochemical cells deliver current through molecular ions. Batteries fall in this category.



                      Resistance:



                      This is the measure of the opposition to current flow. Every wire has some resistance, however you want specific resistor materials to meaningfully resist current flow. It's affected by cross section, and the material used to make it.






                      share|cite|improve this answer








                      New contributor




                      GregoryNeal is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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                      $endgroup$









                      • 1




                        $begingroup$
                        This explanation of voltage is confusing because it does not explain the distinction between potential energy and potential. And it does not hold when the electric field is induced by a changing magnetic field and is therefore non-conservative.
                        $endgroup$
                        – G. Smith
                        3 hours ago


















                      0












                      $begingroup$

                      Voltage:



                      This is the electrical potential energy difference. It's the difference in electric potential between two points. Which is a measure of how much energy it takes to move a test charge between the two points.



                      Current:



                      This is literally a measure of how much electric charge is currently being pushed past a point or region. A current is produced by introducing charge to a voltage. Note, that I use "electric charge" instead of "electrons" because any difference in voltage will result in current flow. For instance, electrochemical cells deliver current through molecular ions. Batteries fall in this category.



                      Resistance:



                      This is the measure of the opposition to current flow. Every wire has some resistance, however you want specific resistor materials to meaningfully resist current flow. It's affected by cross section, and the material used to make it.






                      share|cite|improve this answer








                      New contributor




                      GregoryNeal is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.






                      $endgroup$









                      • 1




                        $begingroup$
                        This explanation of voltage is confusing because it does not explain the distinction between potential energy and potential. And it does not hold when the electric field is induced by a changing magnetic field and is therefore non-conservative.
                        $endgroup$
                        – G. Smith
                        3 hours ago
















                      0












                      0








                      0





                      $begingroup$

                      Voltage:



                      This is the electrical potential energy difference. It's the difference in electric potential between two points. Which is a measure of how much energy it takes to move a test charge between the two points.



                      Current:



                      This is literally a measure of how much electric charge is currently being pushed past a point or region. A current is produced by introducing charge to a voltage. Note, that I use "electric charge" instead of "electrons" because any difference in voltage will result in current flow. For instance, electrochemical cells deliver current through molecular ions. Batteries fall in this category.



                      Resistance:



                      This is the measure of the opposition to current flow. Every wire has some resistance, however you want specific resistor materials to meaningfully resist current flow. It's affected by cross section, and the material used to make it.






                      share|cite|improve this answer








                      New contributor




                      GregoryNeal is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.






                      $endgroup$



                      Voltage:



                      This is the electrical potential energy difference. It's the difference in electric potential between two points. Which is a measure of how much energy it takes to move a test charge between the two points.



                      Current:



                      This is literally a measure of how much electric charge is currently being pushed past a point or region. A current is produced by introducing charge to a voltage. Note, that I use "electric charge" instead of "electrons" because any difference in voltage will result in current flow. For instance, electrochemical cells deliver current through molecular ions. Batteries fall in this category.



                      Resistance:



                      This is the measure of the opposition to current flow. Every wire has some resistance, however you want specific resistor materials to meaningfully resist current flow. It's affected by cross section, and the material used to make it.







                      share|cite|improve this answer








                      New contributor




                      GregoryNeal is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.









                      share|cite|improve this answer



                      share|cite|improve this answer






                      New contributor




                      GregoryNeal is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.









                      answered 3 hours ago









                      GregoryNealGregoryNeal

                      11




                      11




                      New contributor




                      GregoryNeal is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.





                      New contributor





                      GregoryNeal is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.






                      GregoryNeal is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                      Check out our Code of Conduct.








                      • 1




                        $begingroup$
                        This explanation of voltage is confusing because it does not explain the distinction between potential energy and potential. And it does not hold when the electric field is induced by a changing magnetic field and is therefore non-conservative.
                        $endgroup$
                        – G. Smith
                        3 hours ago
















                      • 1




                        $begingroup$
                        This explanation of voltage is confusing because it does not explain the distinction between potential energy and potential. And it does not hold when the electric field is induced by a changing magnetic field and is therefore non-conservative.
                        $endgroup$
                        – G. Smith
                        3 hours ago










                      1




                      1




                      $begingroup$
                      This explanation of voltage is confusing because it does not explain the distinction between potential energy and potential. And it does not hold when the electric field is induced by a changing magnetic field and is therefore non-conservative.
                      $endgroup$
                      – G. Smith
                      3 hours ago






                      $begingroup$
                      This explanation of voltage is confusing because it does not explain the distinction between potential energy and potential. And it does not hold when the electric field is induced by a changing magnetic field and is therefore non-conservative.
                      $endgroup$
                      – G. Smith
                      3 hours ago













                      0












                      $begingroup$

                      This is not a complete answer, but a bit too much for just a comment. I want to just address a couple of points in your question.



                      When you say "current is the velocity of electrons", you're half right. Current measures the total quantity of charge moving through a surface (for example, a cross-section of a wire) per unit time. It could increase if the velocity of the carriers increases, or if there's simply more carriers present moving the same speed. And the carriers could be electrons, or they could be protons (for example, in an ionic solution or a wet cell), or they could be electron holes, but explaining that is probably getting beyond what you need to learn right now.



                      When we say "voltage is like pressure", there we really are making a very loose analogy. Differences in voltage are what exert forces on charge carriers, so differences in voltage are what cause current to flow. In the same way differences in pressure are what cause water to flow in a pipe. But that's where the analogy ends. You shouldn't read anything into it about what creates differences in voltage, how voltage might be distributed in a wire, etc.



                      You should also realize that voltage is not really fundamental. In electrostatics, it's just a way of summarizing the effects of electric fields (as pointed out in another answer, electrostatic voltage is just the integral of electric field along a path). More generally, it can also be produced by changing magnetic fields. But really it's the electric field that actually produces a force on charged particles, not the voltage per se.






                      share|cite|improve this answer









                      $endgroup$


















                        0












                        $begingroup$

                        This is not a complete answer, but a bit too much for just a comment. I want to just address a couple of points in your question.



                        When you say "current is the velocity of electrons", you're half right. Current measures the total quantity of charge moving through a surface (for example, a cross-section of a wire) per unit time. It could increase if the velocity of the carriers increases, or if there's simply more carriers present moving the same speed. And the carriers could be electrons, or they could be protons (for example, in an ionic solution or a wet cell), or they could be electron holes, but explaining that is probably getting beyond what you need to learn right now.



                        When we say "voltage is like pressure", there we really are making a very loose analogy. Differences in voltage are what exert forces on charge carriers, so differences in voltage are what cause current to flow. In the same way differences in pressure are what cause water to flow in a pipe. But that's where the analogy ends. You shouldn't read anything into it about what creates differences in voltage, how voltage might be distributed in a wire, etc.



                        You should also realize that voltage is not really fundamental. In electrostatics, it's just a way of summarizing the effects of electric fields (as pointed out in another answer, electrostatic voltage is just the integral of electric field along a path). More generally, it can also be produced by changing magnetic fields. But really it's the electric field that actually produces a force on charged particles, not the voltage per se.






                        share|cite|improve this answer









                        $endgroup$
















                          0












                          0








                          0





                          $begingroup$

                          This is not a complete answer, but a bit too much for just a comment. I want to just address a couple of points in your question.



                          When you say "current is the velocity of electrons", you're half right. Current measures the total quantity of charge moving through a surface (for example, a cross-section of a wire) per unit time. It could increase if the velocity of the carriers increases, or if there's simply more carriers present moving the same speed. And the carriers could be electrons, or they could be protons (for example, in an ionic solution or a wet cell), or they could be electron holes, but explaining that is probably getting beyond what you need to learn right now.



                          When we say "voltage is like pressure", there we really are making a very loose analogy. Differences in voltage are what exert forces on charge carriers, so differences in voltage are what cause current to flow. In the same way differences in pressure are what cause water to flow in a pipe. But that's where the analogy ends. You shouldn't read anything into it about what creates differences in voltage, how voltage might be distributed in a wire, etc.



                          You should also realize that voltage is not really fundamental. In electrostatics, it's just a way of summarizing the effects of electric fields (as pointed out in another answer, electrostatic voltage is just the integral of electric field along a path). More generally, it can also be produced by changing magnetic fields. But really it's the electric field that actually produces a force on charged particles, not the voltage per se.






                          share|cite|improve this answer









                          $endgroup$



                          This is not a complete answer, but a bit too much for just a comment. I want to just address a couple of points in your question.



                          When you say "current is the velocity of electrons", you're half right. Current measures the total quantity of charge moving through a surface (for example, a cross-section of a wire) per unit time. It could increase if the velocity of the carriers increases, or if there's simply more carriers present moving the same speed. And the carriers could be electrons, or they could be protons (for example, in an ionic solution or a wet cell), or they could be electron holes, but explaining that is probably getting beyond what you need to learn right now.



                          When we say "voltage is like pressure", there we really are making a very loose analogy. Differences in voltage are what exert forces on charge carriers, so differences in voltage are what cause current to flow. In the same way differences in pressure are what cause water to flow in a pipe. But that's where the analogy ends. You shouldn't read anything into it about what creates differences in voltage, how voltage might be distributed in a wire, etc.



                          You should also realize that voltage is not really fundamental. In electrostatics, it's just a way of summarizing the effects of electric fields (as pointed out in another answer, electrostatic voltage is just the integral of electric field along a path). More generally, it can also be produced by changing magnetic fields. But really it's the electric field that actually produces a force on charged particles, not the voltage per se.







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered 18 mins ago









                          The PhotonThe Photon

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