40 votes

What is watts, volts and amps?

I never really understood, and any definition I read, I just forget after a while. can someone explain in a way that I won't forget.

the water analogy doesn't help as I get confused between them. also, Watt is the most confusing for me shouldn't it with some unit of time ? like I could say how much water is flowing per second but just saying how much water is flowing without the time wouldn't be very useful, it could be seconds, minutes, hours. yet, the Watt is never written with respect to time, why is that?

48 comments

  1. [14]
    derekiscool
    (edited )
    Link
    A watt does have time! It's equal to 1 Joule per second of energy transfer. That's also why power consumption is often measured in Kilowatt-Hours, rather than just Kilowatts, by electric meters....

    A watt does have time! It's equal to 1 Joule per second of energy transfer. That's also why power consumption is often measured in Kilowatt-Hours, rather than just Kilowatts, by electric meters. 1KWh is equal to 1000 watts of power being used for 1 hour.

    Using the common water analogy you mentioned, the way I like to think of it is that Volts are like the water pressure, amps are the speed (or flow rate) of the water, and watts are the total water moved per second.

    In reality, the only difference is that instead of moving water, we're moving electrons. That's why the water analogy is so effective.

    I suppose this doesn't entirely answer your question, since I'm still using the water analogy, but I genuinely can't think of another way to explain it. I'll ponder for a while, maybe I can think of another analogy with some time.

    30 votes
    1. [12]
      updawg
      Link Parent
      Well, ackshually...

      In reality, the only difference is that instead of moving water, we're moving electrons.

      Well, ackshually...

      24 votes
      1. Baeocystin
        Link Parent
        ...so you want to field this one? :D

        ...so you want to field this one? :D

        20 votes
      2. [10]
        chocobean
        Link Parent
        I've been meaning to ask all thread, so the marbles through a tube style water analogy for electric fields is wrong right?

        I've been meaning to ask all thread, so the marbles through a tube style water analogy for electric fields is wrong right?

        3 votes
        1. [8]
          updawg
          Link Parent
          The electrons don't move. In DC, they move at something like a few millimeters per hour. In AC, they literally just oscillate back and forth without really moving. If you have a lot of time, here...
          • Exemplary

          The electrons don't move. In DC, they move at something like a few millimeters per hour. In AC, they literally just oscillate back and forth without really moving. If you have a lot of time, here are some explanations that will help you not understand electricity as well as anyone else doesn't understand electricity because basically no one really understands electricity that well:

          Veritasium: The Biggest Misconception About Electricity

          Comment 1 indicative of problems people had with the video I teach physics at the University of California, San Diego, including this very topic. Within an hour of watching this, I set up the experiment, and got the result. I have photographs of the experimental setup, and of the oscilloscope traces. I discussed the results at length with a physics professor friend, and we agree on the explanation. In fact, the load gets (nearly) the full voltage (almost) immediately; there is no (visible) ramp-up time, nor delay through the long wires (delay < 10 ns). This is fully consistent with transmission line theory that is well established for about a century. Dr. Muller's Veritasium series is great, but in this case, there are several claims that are incorrect, or at least misleading. There are many subtleties, and I cannot do them justice in a comment. I would enjoy talking with Dr. Muller to clear these up. For reference, I have a BS in Electrical Engineering, a PhD in physics, and I am author of "Quirky Quantum Concepts", an upper-division/graduate quantum mechanics text supplement. This is my first Youtube comment ever.

          Update: I love the Veritasium series, and I have learned a lot from it. To respond to some replies: I chose the simplest case, which I think illustrates the point that power can reach the load without going the whole length of the "wings." The analysis link below the video covers the more-complicated case. My "wings" are 50' hardware store extension cords. My propagation test confirms that coiling them doesn't matter, as expected. My analysis is fully transient, and the circuit transits to steady-state DC over time. Resistance can safely be approximated as zero, but inductance and capacitance cannot, as expected by theory. My load is 270 ohm, roughly the on-resistance of a 50 W incandescent bulb. The characteristic impedance Z ~53 ohm, which is substantially less than the load; that's what's needed for the simple case of near full response nearly immediately (the load is not matched to Z). In this case, the wing capacitance dominates the behavior.

          Consolidating my previous reply: Examples of subtleties: Do two electrons repel each other? (a) Most people would say yes, and I agree. But one could argue (b) No, one electron creates an electric field, and that field pushes on the other electron. This is also correct; it's slightly more detailed, and from a somewhat different viewpoint, but (a) is still correct, as well. But (c) In calculating the force of (b), we use only the E-field from one electron, even though we know both produce E-fields. To use the full E-field, we have to compute force with the Maxwell stress tensor; this is also correct. There are multiple correct views one can take. The video's chain analogy is very good, and correct. Separately, a few replies have hit on the most-direct (IMO) explanation: the capacitance in the wires provides an immediate, physically short path for the electricity to reach the load. The path of current changes over time. Your gut might tell you that the capacitance is too small, but a quantitative transient analysis using standard circuit theory matches the experiment. Special Relativity still stands. More subtleties: characteristic impedance, etc. I do similar demonstrations in class, so I happen to have all the equipment and experience ready to go.

          Comment 2

          EE here; I think most of this info is technically correct, but potentially misleading in some areas.

          For one, while it's true that energy is transferred in the space around a conductor, as opposed to through the conductor, the vast majority of that transfer is taking place extremely close to the conductor (we're talking millimeters, typically), due to both the magnetic and electric field strengths decreasing exponentially with distance from the conductor. So in reality, the energy being transferred actually decreases superexponentially with distance from the conductor. Now, in power lines, the ground is still a concern because it's a very long conductor, carrying very high voltage, at very high currents; it's a somewhat extreme case. Yet, even though the cable is miles long, we only need to separate it from the ground by tens of meters to significantly reduce losses over that long distance. Furthermore, the ground is only a problem because power lines are AC. If they were DC, you could lay the cable right on the ground, and you wouldn't get any significant energy loss.

          Edit: see below, the dropoff is not actually superexponential, but the general idea that energy transfer is greater closer to the conductor is still accurate.

          For two, the analogy of electron flow being like water through a tube is actually still accurate in the case of the undersea transmission line. The metal rings around the cable cause a change in electrical impedance for that section of the cable. In the case of water in a tube, this would be analogous to having an air bubble trapped in your tube. As a pressure wave travels through the water, it will suddenly hit this air pocket, which is far more compressible than the water (i.e. has a different impedance), which will cause the waveform to distort in precisely the same manner as the electric wave does in the cable. Some energy will pass through the bubble, creating your distorted (attenuated) waveform, and the rest of the energy will actually become a wave reflected back in the other direction. This is precisely what's causing the distortions in the undersea transmission line. There's a bunch of reflected waves bounding back and forth between all the iron rings that stretch and distort the original signal. (for the real electrical nerds, check out "time domain reflectometry", which uses this principle to precisely detect where a fault exists on a power line)

          Third; yes, energy transfer from the switch to the bulb will occur in 1/c time (by the way, I think you could clarify this by representing it as d/c time, where d is distance from the switch to the bulb. You never really state where the 1 comes from in that equation (at first I thought you were implying it was a constant value, unrelated to this distance)). And yes, you do clarify that it will only be a fraction of the steady state energy. But I think you should stress that this would be an extremely small portion of that steady state energy. The initial energy that the bulb receives will only be due to the capacitive and magnetic coupling between the two long portions of the conductor. And in the case of wire separated by 1 meter, both the capacitive and magnetic coupling would be practically zero. This again is due in part to the exponentially decaying electrical and magnetic field strengths with distance from the conductor, as well as the poor electric and magnetic permiativity of the dielectric (air) between the conductors.

          Fourth; addressing your question about "why is energy transferred during one half cycle, but not returned back to the plant in the other half of the cycle", I think your physical demonstration actually explains that perfectly. No matter which end of the chain you pull, there's something down the line offering resistance to the motion of the chain. Heck, you even get friction between the chain and the tube, which is like resistance in electrical conductors. However, if you attached a sort of clock spring to your wheel (such that the spring always worked to return the wheel to its at-rest position), you would indeed see some energy returned to the power plant (you) on the second half of the cycle. This is analogous to powering a capacitive load with AC.

          Veritasium: How Electricity Actually Works

          Styropyro: Is it the volts or amps that kill?

          I'm sure there are more, possibly better explanations, but these do go through a lot of misconceptions and they may help illustrate why I was comfortable commenting "Well, ackshually..." but not anything further!

          15 votes
          1. [2]
            teaearlgraycold
            Link Parent
            The electro magnetic force is just really really strong. If all of the electrons in a wire were pumped through in a second it would create a sizable explosion. If your left hand had 1% more...

            The electro magnetic force is just really really strong. If all of the electrons in a wire were pumped through in a second it would create a sizable explosion. If your left hand had 1% more electrons than your right you’d explode with as much force as a nuclear bomb. When something holds an electrical charge it’s only got a tiny fraction of an excess (or deficit of) electrons.

            5 votes
            1. updawg
              Link Parent
              More sensationalist lies, smh. You'd really explode with the force of tens of millions of nuclear bombs.

              If your left hand had 1% more electrons than your right you’d explode with as much force as a nuclear bomb.

              More sensationalist lies, smh. You'd really explode with the force of tens of millions of nuclear bombs.

              4 votes
          2. [5]
            chocobean
            Link Parent
            [image of Chocobean falling into an infinite dark spiral of dual confusion and amazement at our universe] :| are there ..... super dumb introduction physics books you could recommend for middle or...

            [image of Chocobean falling into an infinite dark spiral of dual confusion and amazement at our universe]

            :| are there ..... super dumb introduction physics books you could recommend for middle or highschool level? I pity-passed highschool physics kinda gave up after that. Took Calculus/Physics for programmers and passed because that I can do. Not sure if it's the ADHD of making small mistakes at the beginning of calculations that snowball downhills, or something more fundamentally wrong about retention of my understanding of basic concepts. I had good teachers too, it wasn't their fault.

            4 votes
            1. [2]
              Banazir
              Link Parent
              I don't have any book recommendations at the moment, but I highly recommend taking a step back and learning kinematics before you touch the physics of electricity and magnetism. Kinematics is just...

              I don't have any book recommendations at the moment, but I highly recommend taking a step back and learning kinematics before you touch the physics of electricity and magnetism. Kinematics is just the physics of bigger stuff - if you throw this ball at this angle and this velocity, how far will it go? There's a surprising amount of overlap between concepts, but with kinematics you can see or visualize the effects pretty easily.

              For books, maybe check your local library first? Usually the kids section has a sub-section for science, and while it may be lower level than you wanted it could also lead to some good results.

              9 votes
              1. chocobean
                Link Parent
                That's a good idea to re-start with kinematics and firm up on that first, thanks :)

                That's a good idea to re-start with kinematics and firm up on that first, thanks :)

                5 votes
            2. [2]
              updawg
              (edited )
              Link Parent
              I would say the fun part is that there isn't, really. You can always simplify, but the more you do that, the more it breaks down, and I don't think you can break it down anymore without it falling...

              I would say the fun part is that there isn't, really. You can always simplify, but the more you do that, the more it breaks down, and I don't think you can break it down anymore without it falling apart.

              We're at the point where even a lot of intelligent, educated people misunderstand. Even I'm basically just regurgitating stuff without much of a deeper understanding. That shouldn't surprise anyone who saw my E&M grades in college...

              7 votes
              1. kacey
                Link Parent
                Not that this helps, but on the topic of there not being great introductory books on electromagnetism which also do not take liberties with the mathematics, I've always wanted to write an edugame...

                Not that this helps, but on the topic of there not being great introductory books on electromagnetism which also do not take liberties with the mathematics, I've always wanted to write an edugame to teach this stuff on a human scale. There've been some (relatively) fun puzzle games which play around with special relativity, for example, and which provide a better intuition than drilling through textbook questions.

                Slowing down waves, scaling up quantum phenomena, visualizing invisible fields, etc. seem like they could do a lot for helping people build a strong foundation to work off of. Play is such an underexplored teaching method, especially in adults.

                2 votes
    2. davek804
      Link Parent
      I wonder if the whole duality of light thing would be useful to bring into the discussion when using the water metaphor to explain electricity? Duality of light: a photon is both a wave and a...

      I wonder if the whole duality of light thing would be useful to bring into the discussion when using the water metaphor to explain electricity?

      Duality of light: a photon is both a wave and a particle. Generally, at least when I was in basic chemistry, we didn't have a way to observe both states at once. You build a form of measure and can see one or the other

      So yeah, mentally, when I think of electricity, I think of it as both a particle and a wave. But I'm just a non-scientific pleb.

      3 votes
  2. [12]
    Barney
    (edited )
    Link
    I'm going to try a different analogy, maybe that helps you a bit! You asked about 3 things, watts (power), amps (electric current) and volts (electric potential). Current (amps) I'll start with...

    I'm going to try a different analogy, maybe that helps you a bit!

    You asked about 3 things, watts (power), amps (electric current) and volts (electric potential).

    Current (amps)

    I'll start with current, since that's the easiest. I'm going to operate under the assumption that you know what electrons are. Current is how many electrons flow / go in a particular direction. Amps is the international unit we use today, but it could be anything, really. It's some factor of "number of electrons / second" going in this direction.

    Voltage (volts)

    Imagine having a ball on a flat surface. If you just leave the ball there, nothing happens. That's 0 volts, or 0 electric potential. Now if you imagine a hill, if you put a ball anywhere on the slope, that ball will want to roll downhill. By doing some work yourself, you can roll the ball uphill, but it will want to roll downhill normally, and you need to work against that. The steeper the hill, the higher the voltage. You can imagine electric potential like that too, just for electrons and wires instead of a ball and a hill. The wall outlet is generally 230V (or 110V if you're in the US) 200-240V in most places, and 100-130 in a select few. This is just a metric for "how strong the electrons want to come out of there". This isn't perfectly accurate, but I hope it gets the idea across.

    Aparte: here's a handy map for supply voltage if you're interested. Thanks for letting me know @kari and @sparksbet, I actually did not know this!

    Power (watts)

    This is pretty simple too. It's how much work the given thing is doing per second. A watt is defined as "Joule / second", but it's essentially just "energy / time". A fun little addendum, power is voltage * current, so: watt = volts * amps. :)

    11 votes
    1. [2]
      Sunbutt23
      Link Parent
      We always said in physics class

      We always said in physics class

      Power is Very Important (P=V*I)

      12 votes
      1. kari
        Link Parent
        I always said (to myself) “penis in vagina” => P=IV lmao

        I always said (to myself) “penis in vagina” => P=IV lmao

        14 votes
    2. [6]
      kari
      (edited )
      Link Parent
      Hey, we’re 120V. There’s also Japan where it’s 100V and, depending whether you’re east or west of Tokyo, can have different frequencies (50Hz in half the country, 60Hz in the other half)

      The wall outlet is generally 230V (or 110V if you're in the US)

      Hey, we’re 120V. There’s also Japan where it’s 100V and, depending whether you’re east or west of Tokyo, can have different frequencies (50Hz in half the country, 60Hz in the other half)

      7 votes
      1. [5]
        chocobean
        Link Parent
        Two frequencies ??? Why is that and why haven't they tried to unify to just one frequency and does it affect electronics or why not?

        Two frequencies ??? Why is that and why haven't they tried to unify to just one frequency and does it affect electronics or why not?

        3 votes
        1. [4]
          updawg
          Link Parent
          Companies in Japan bought technology from Europe and from the US. Then is was too difficult and expensive to merge. These days, almost everything there is dual voltage, anyway, so it isn't worth...

          Companies in Japan bought technology from Europe and from the US. Then is was too difficult and expensive to merge. These days, almost everything there is dual voltage, anyway, so it isn't worth it really.

          6 votes
          1. [3]
            chocobean
            Link Parent
            Dare I ask how dual voltage works? Like, the wall sockets deliver both or that appliances expect either? If it's the former is it kind of like a line of kids at the top of two water slides and...

            Dare I ask how dual voltage works? Like, the wall sockets deliver both or that appliances expect either? If it's the former is it kind of like a line of kids at the top of two water slides and each can choose which slide to go down depending on which one seems ready for more kids? Or if it's like the latter then each appliance can speak French and English?

            3 votes
            1. sparksbet
              Link Parent
              I'm fairly certain it's the latter. You already probably own several dual voltage appliances yourself -- most laptops and similar electronics are dual voltage. The chonky part of the charger...

              I'm fairly certain it's the latter. You already probably own several dual voltage appliances yourself -- most laptops and similar electronics are dual voltage. The chonky part of the charger (whether it's separate from or part of the actual bit you plug in to the wall) does the work of converting the voltage (and presumably other attributes of the electricity) to whatever the device expects.

              This is why, when you're an American traveling to Europe, you can bring your laptop and charge it with only a plug adapter, whereas if you do this with an appliance that isn't dual voltage, especially one that uses heat or has a motor, you will have a very bad time unless you get a voltage converter.

              5 votes
            2. kovboydan
              Link Parent
              Appliances expect either, probably. I don’t know about Japan specifically, but if you look at the back of your game console / appliances / PSU with a removable power cable (C8 or C13). On many,...

              Appliances expect either, probably. I don’t know about Japan specifically, but if you look at the back of your game console / appliances / PSU with a removable power cable (C8 or C13). On many, but not all, devices there will be tiny text that says 100/240v 50-60hz).

              Orange Amps have it too but I think most require a different fuse as well as the flip of a switch.

              5 votes
    3. [3]
      sparksbet
      Link Parent
      I appreciate not being strictly US-centric here, but given that this site is based in Canada, it would probably be better to say "North America (and a couple other exceptions)". It would also be...

      The wall outlet is generally 230V (or 110V if you're in the US)

      I appreciate not being strictly US-centric here, but given that this site is based in Canada, it would probably be better to say "North America (and a couple other exceptions)". It would also be more accurate (and less Eurocentric) to say 220-240V rather than 230V, since you do cover most of the world with that range but not necessarily with 230V specifically.

      5 votes
      1. [2]
        lostwax
        Link Parent
        I think most of the 240V world has moved to 230. My hazy understanding is that Australia did this, at least at first, by changing absolutely nothing, just saying 230 instead of 240 and making the...

        I think most of the 240V world has moved to 230. My hazy understanding is that Australia did this, at least at first, by changing absolutely nothing, just saying 230 instead of 240 and making the acceptable tolerance include what was already the case.

        1 vote
        1. sparksbet
          (edited )
          Link Parent
          While it's true that there are very few (albeit not zero) countries on 240V, a sizeable chunk of the world is on 220V, however, including the world's most populous country and large portions of...

          While it's true that there are very few (albeit not zero) countries on 240V, a sizeable chunk of the world is on 220V, however, including the world's most populous country and large portions of South America and Africa. Especially given the history of Europe failing to acknowledge that it isn't the center of the world, it's preferable to spend the trivial energy of putting the range to more accurately describe most of the globe rather than expecting parts of the world where you don't live to fall into the "acceptable tolerance." Particularly since the comment contained another inaccuracy to edit for anyway, it's probably worth the 4-5 keystrokes to be more accurate and inclusive.

          And anyway the person I replied to already edited their comment, and we all got to learn a little bit about mains voltage around the world. That map certainly made me wanna figure out wtf Brazil has going on with its mains voltage, for instance.

          1 vote
  3. kari
    Link
    Power is energy over time and, like @derekiscool said, 1 W = 1 J/s, so it’s just inherently there. Horsepower is also a measure of power, equal to 745.7 W or 745.7 J/s, but you probably never...

    the Watt is never written with respect to time, why is that?

    Power is energy over time and, like @derekiscool said, 1 W = 1 J/s, so it’s just inherently there. Horsepower is also a measure of power, equal to 745.7 W or 745.7 J/s, but you probably never question why cars aren’t rated in “hp/second” or something like that. It’s the same idea.

    9 votes
  4. [3]
    tomf
    Link
    This might help - https://i.imgur.com/yNMWeDv.jpeg
    6 votes
    1. [2]
      0x29A
      Link Parent
      Would it be appropriate then to consider "watts" a measurement of the combined "amount of work being accomplished" by the amp and volt beings (in this image) per second? I was going to say effort,...

      Would it be appropriate then to consider "watts" a measurement of the combined "amount of work being accomplished" by the amp and volt beings (in this image) per second?

      I was going to say effort, but that sounds more like volts, and then I was going to say "the calories the amp and volt beings are expending per second in the image" but then I remembered the whole calories and joules relationship and then the analogies maybe get messy lmao... still fun to try and analogize/visualize these

      3 votes
      1. tomf
        Link Parent
        yeah, I think its fair to say that about watts. Watts is just v*a of all things, I think this always has the best and worst analogies.

        yeah, I think its fair to say that about watts. Watts is just v*a of all things, I think this always has the best and worst analogies.

        1 vote
  5. [2]
    skybrian
    Link
    Watts tell you energy consumption. For example, a light bulb consumes a steady amount of electricity when it’s turned on. A 100 watt light bulb consumes twice as much as a 50 watt bulb, or the...

    Watts tell you energy consumption. For example, a light bulb consumes a steady amount of electricity when it’s turned on. A 100 watt light bulb consumes twice as much as a 50 watt bulb, or the same as two 50 watt bulbs.

    (When connected in parallel, and ignoring things like dimmer switches.)

    As others have said, it’s implicitly per second. You need to multiply by the time that the light bulb is left on to get energy used.

    If you want a water analogy, a bigger pipe will let more water flow through it than a smaller pipe. But you could have two smaller pipes that are equivalent to a bigger one.

    4 votes
    1. kovboydan
      Link Parent
      To explicitly connect this with the 1 J/s parts of comments: 1 W for one second would be 1 J/s x 1 s, the seconds would cancel out, and you’d be left with 1 J.

      As others have said, it’s implicitly per second. You need to multiply by the time that the light bulb is left on to get energy used.

      To explicitly connect this with the 1 J/s parts of comments: 1 W for one second would be 1 J/s x 1 s, the seconds would cancel out, and you’d be left with 1 J.

      5 votes
  6. [2]
    Englerdy
    (edited )
    Link
    I'll take a stab at something really short and maybe a bit more conceptual*: Watts: How much energy is flowing every second Volts: How strongly motivated electrons are to move Amps: How many...

    I'll take a stab at something really short and maybe a bit more conceptual*:
    Watts: How much energy is flowing every second
    Volts: How strongly motivated electrons are to move
    Amps: How many electrons are flowing every second


    And then some slightly longer explanations maybe:
    Watts is power transfer which comes from the combination of voltage (motivation for electrons to move) and amps (how many electrons are flowing). Watts can also be used for heat flow (how much thermal energy moves every second) which may or may not be helpful for remembering.

    Voltage is often called a potential. You could almost think of it like a rubber band or spring. Without pulling it has zero potential, but as you stretch it, there's increasingly greater potential energy that can be released when you let it go for it to jump back to its unexpanded state. Voltage relates how motivated electrons are move from a high voltage ("stretched out") to a low voltage (a resting state).

    Amps are measuring the individual electrons as they race from a high voltage to a lower voltage (which is electric current). This is the water in the water analogy. But could also be marbles rolling down a hill. It's counting how many run by every second on their way down.

    You didn't mention it, but thinking of resistance also helps intuition. For the rubber band/spring anology, resistance is kind of like the air the rubber band or spring is sitting in. When the spring gets released, air doesn't really resist it snapping back to its original shape. But if you held the spring in honey or molasses and stretched it, you'd see it contract more slowly because of it needing to move really thick liquid out of the way. Resistance slows down the rate that electrons move from high voltage to low voltage. So for the same voltage, it affects how quickly electrons flow and as a result, how much energy moves every second.

    *Trying to keep this pretty abstract, I know these aren't especially rigorous explanations.

    4 votes
    1. cuteFox
      Link Parent
      I didn't mention resistance because it was actually the easiest for me to understand, it's just really intuitive

      I didn't mention resistance because it was actually the easiest for me to understand, it's just really intuitive

      1 vote
  7. chocobean
    Link
    Not an expert, in fact, someone also often confused and trying to figure it out again. I'm assuming, @cutefFox, you're like me in that when I'm actively reading the definitions and such it makes...

    Not an expert, in fact, someone also often confused and trying to figure it out again. I'm assuming, @cutefFox, you're like me in that when I'm actively reading the definitions and such it makes sense, and then when I turn around I forget which is which. It's not so much understanding as remembering. When one has to remember "arbitrary" or separate easily confused things, sometimes it helps to be completely absurd. I'll attempt with Watts/power since P = V * I

    (Incidentally, I in italicized-French is initially intensité du courant )

    Corrections very much begged for, please and thank yous

    summary of definitions others have given about Watts /Power.

    It's how much work the given thing is doing per second. A watt is defined as "Joule / second", but it's essentially just "energy / time". --- @Barney

    A watt does have time! It's equal to 1 Joule per second of energy transfer. That's also why power consumption is often measured in Kilowatt-Hours, rather than just Kilowatts, by electric meters. 1KWh is equal to 1000 watts of power being used for 1 hour. --- @derekIsCool

    Watts tell you energy consumption. For example, a light bulb consumes a steady amount of electricity when it’s turned on. A 100 watt light bulb consumes twice as much as a 50 watt bulb, or the same as two 50 watt bulbs. (When connected in parallel, and ignoring things like dimmer switches.) --- @skybrian

    Watts is power transfer which comes from the combination of voltage (motivation for electrons to move) and amps (how many electrons are flowing). --- @Englerdy

    Absurd example attempted as memory aid only : very little science is happening here

    Meet Watt-Person, a powerful superhero whose superpower is powerfully measured in Watts. Wherever they go, when their powers are activated, the crowd can't help but exclaim Waaaaaaat! from sheer disbelief at their powerful power. Put another way, their power leve can be expressed as the number of "Waaaaaaat!" you can hear from the crowds. But what is behind each "Waaaaaaat!", you ask?

    Watt-Person can consume, transfer, or convert energy. Let's zoom in on today when Watt-Person is demonstrating their power at a March For Democracy rally, where they are consuming energy at an unbelievable rate! Today's energy unit is Jellyrolls per second because that awful dictator recently got pelted by a jellyroll and then he slipped on that jellyroll and face planted and his pants fell off and everyone saw his diapers and laughed. So today, when Watt-Person is demonstrating their powers expressed in J/s, the crowd erupts into cheers of "Waaaaaaat!" proportional to Jellyrolls per second Watt-Person is consuming.

    Of course, like any superhero, there's some sort of Kryptonite limiting their powers. Watt-Person loves democracy, and they love the current culture of their beloved home planet. When fair and proportional democratic Volts are being suppressed, Watt-Person gets sad and their Power goes down a little. When the Current culture is being dismissed by the administration, Watt-Person feels a little less powerful as well. But don't worry! Watt-Person loves the entire planet, and when they fly to the next country where fair Volts and abundant Current culture is celebrated, their energy is multiplied and they fly back in to inspire "Waaaaaaat!" cheers from the crowd.

    (Watt-Person firmly believes that Democracy is achieved by Volts, so they don't personally depose dictators. According to them, we the people have actual power, they just convert that energy into a crowd pleasing visual format.)

    4 votes
  8. [2]
    Perryapsis
    (edited )
    Link
    In addition to the other analogies already given, it might help to think in terms of the apocryphal story of Isaac Newton discovering gravity by watching apples fall from a tree. Suppose he didn't...

    In addition to the other analogies already given, it might help to think in terms of the apocryphal story of Isaac Newton discovering gravity by watching apples fall from a tree. Suppose he didn't see apples falling in a gravitational field, but instead saw charges falling in an electric field:

    Newton reasons that there must be some energy that gets released when an apple falls from a tree and, being Newton, starts thinking about machines that could harness that energy and how much of that energy he could use. What kind of trees will give him the most energy? He notes two things:

    1. Taller trees give you more energy per apple. Tall trees don't necessarily have bigger or more apples, but they release more energy per apple when they drop them because of their great height. And

    2. Trees that drop a lot of apples quickly give you more energy quickly. A tree that drops an apple once every two weeks isn't going to give you much energy even if it's very tall. Meanwhile you can get a lot of energy out of a short tree if it's ripe and dropping an apple every five minutes.

    In electrical terms, we say that the trees with property 1 have high voltage, while the trees with property 2 have high current (amps). Taken together, a given tree's height and drop rate determine how quickly we can get energy out of it (watts).

    4 votes
    1. Pistos
      Link Parent
      Wow. This explanation is really sticking for me. Good job. Even this makes sense: becomes total_apple_energy_supply = tree_height * apple_drop_rate

      Wow. This explanation is really sticking for me. Good job. Even this makes sense:

      P = V x I

      becomes

      total_apple_energy_supply = tree_height * apple_drop_rate

      3 votes
  9. stewedrabbit
    Link
    If you want a really good analogy you can feel, and are happy to spend some money on it (and in return be able to build circuits eventually), I can really recommend Spintronics (from Upperstory)....

    If you want a really good analogy you can feel, and are happy to spend some money on it (and in return be able to build circuits eventually), I can really recommend Spintronics (from Upperstory). The focus seems more kids/youngsters, but I can attest adults also get their kick out of it.

    3 votes
  10. kovboydan
    Link
    I refreshed before posting so I’ll only leave this part: A watt is 1 J/s so it “is“ per second. It might help to look at the SI base units and cancel out various units like time (s) to see how V,...

    I refreshed before posting so I’ll only leave this part:

    A watt is 1 J/s so it “is“ per second.

    It might help to look at the SI base units and cancel out various units like time (s) to see how V, A, and W relate.

    2 votes
  11. kacey
    Link
    May I ask if there's a context in which this came up recently? Perhaps providing an answer in terms of something that you run into frequently would stick in your head better than something to do...

    May I ask if there's a context in which this came up recently? Perhaps providing an answer in terms of something that you run into frequently would stick in your head better than something to do with water?

    2 votes
  12. [2]
    FlappyFish
    Link
    I’ve seen a lot of explanations, but looking at something from more angles never hurts, so I’ll give one. I’ve always found that when explaining electricity people always start with current and...

    I’ve seen a lot of explanations, but looking at something from more angles never hurts, so I’ll give one. I’ve always found that when explaining electricity people always start with current and voltage, then use that to derive energy, power, charge, etc. But I find those quantities more “real” so I’ll start with them.

    Charge

    Charge is just a quantity particles have which causes them to repel particles of the like charge. In electrical circuits, the particle moving about is the electron, so you can just think of charge as some number of electrons. The usual unit for charge is the Coulomb (C) which is approximately 6 quintillion electrons worth of charge.

    Energy

    Energy is really hard to describe, so I’m just going to assume that you understand a typical idea of energy. Energy is measured in Joules

    Power

    Power is the amount of energy being used in a given time (the rate of energy usage). Power is measured in watts, which equals one Joule per second (1 J / s). I assume this is what you got confused with with “per time”. The quantity of power is measured as “energy per time” whereas the specific unit the Watt is given as “1 Joule per second”.

    Current

    In an electric circuit, charges flow round the circuit. These charges are moving round at a constant speed, so through a point a set number of charges pass per unit time. Current measures this flow of charge and its unit is the Ampere (Amp) defined as one Coulomb per second (1 C / s)

    Voltage

    Voltage is the “strength” with which charges are pushed round the circuit. It’s defined as the energy per unit charge being pushed. A volt measures voltage and is defined as 1 Joule per Coulomb (1 J / C)

    It’s important to note that voltage is used to refer to two similar concepts that mean slightly different things.
    The first is the electromotive force (emf). This is what I defined earlier as the “strength” being used to push the electrons around. This comes from a battery or a generator.
    Second is the voltage “used” by components. When a current flows through a component in a circuit, the component uses some energy, and as voltage is the amount of energy per charge, it “uses” some voltage. Typically you wouldn’t say it like this, you’d usually say there’s a potential difference, which is just a synonym for voltage.
    Because voltage is energy per charge, it needs to be conserved, so the amount of voltage provided by a power supply is used up completely by all the components of the circuit. So if there is one component, the potential difference over the component is equal to the emf provided by the power supply. If there are multiple, then the emf provided is equal to the sum of the potential differences across all the components (how this is distributed is determined by their resistances)

    Bonus

    I doubt this will be useful to OP, but I like thinking in terms of equations, so here are the points I made earlier in equation form.

    V = E/Q
    I = Q/t
    P = E/t = IV
    E = IVt
    sum of V = 0
    Vcomponent/Vtotal = Rcomponent/Rtotal
    V = IR

    2 votes
    1. sparksbet
      Link Parent
      The existence of the unit "Watt hour", which includes a time word in the name but counterintuitively measures energy rather than energy over time (it's equal to 3600 Joules), probably doesn't help...

      I assume this is what you got confused with with “per time”.

      The existence of the unit "Watt hour", which includes a time word in the name but counterintuitively measures energy rather than energy over time (it's equal to 3600 Joules), probably doesn't help either. It makes sense that it exists irl for practical purposes but probably doesn't help with understanding how the units work.

      3 votes
  13. stu2b50
    Link
    It is. Watts are just j/s. It's just given a name since it's a common unit. This isn't even a particularly electrical unit, it's used everywhere. Volts: imagine if you invented a unit, say, P, and...

    Watt is the most confusing for me shouldn't it with some unit of time

    It is. Watts are just j/s. It's just given a name since it's a common unit. This isn't even a particularly electrical unit, it's used everywhere.

    Volts: imagine if you invented a unit, say, P, and say it's equal to g * h, that is, the gravitational acceleration at a specific field distance * the separation between the two objects. If you were to multiply this P by mass, you'd have energy. E = g * m * h. Similarly, if you multiply volts by coloumbs - that is, charge - you get energy. That's why it's usually called electric potential. IF there was charge, how much energy would there be? Or, per every unit of charge, how much energy is in the electromagnetic field?

    Amps: charge / second. That shouldn't be too hard to intuit. Maybe more useful, think of what is missing. Amps describes how much charge is going in; does that tell you how much energy is in the system? No, because you don't know how much energy each charge has. Charge is like mass in gravity. You don't know how much energy is in a gravitational system when I tell you just the masses. A car floating 100m in the sky has more energy than a car on the ground - that is evident by the fact that car will fall down and explode if it is 100m in the sky. The height and gravitational constant is required to tell you how much each unit of mass has how much energy.

    What tells you how much energy each charge has? Voltage.

    1 vote
  14. [5]
    Akir
    Link
    If I may take the wider perspective, I wonder how long it will be until AI completely supplants this kind of post? I’ve been using Claude to cram quiz questions and explain difficult concepts and...

    If I may take the wider perspective, I wonder how long it will be until AI completely supplants this kind of post? I’ve been using Claude to cram quiz questions and explain difficult concepts and it’s been going pretty well I think. It’s one of those things that is easy to forget that everyone isn’t doing after a while.

    1 vote
    1. [3]
      kovboydan
      Link Parent
      I flip flopped on whether or not this comment was worth posting, but I’ve decided to just throw it out there: I don’t use ChatGPT for anything more than “shit post images” with deep cut...

      I flip flopped on whether or not this comment was worth posting, but I’ve decided to just throw it out there:

      I don’t use ChatGPT for anything more than “shit post images” with deep cut references, but in doing so I recently had a reason to “argue” with it. It confidently asserted something that was wrong. If I didn’t know the subject, it would’ve been believable.

      I hope it keeps going well for you, but you know, maybe remember it can be wrong and sometimes the way it’s wrong is so subtle that you’d only recognize it if you have a mastery of the subject yourself.

      3 votes
      1. [2]
        kacey
        Link Parent
        (probably worth noting that this is also true of responses made by confident humans, too 😅 I tend to read LLM responses like I would a Redditor's post: it probably contains more truth than...

        [...] sometimes the way it’s wrong is so subtle that you’d only recognize it if you have a mastery of the subject yourself.

        (probably worth noting that this is also true of responses made by confident humans, too 😅 I tend to read LLM responses like I would a Redditor's post: it probably contains more truth than fiction, but only probably)

        1 vote
    2. chocobean
      Link Parent
      Supplant (A) the impulse to ask real humans and hence the need for this kind of post, or (B) supplant answers so all our human op would get is garbage AI answers? Hopefully neither and never here....

      Supplant (A) the impulse to ask real humans and hence the need for this kind of post, or (B) supplant answers so all our human op would get is garbage AI answers?

      Hopefully neither and never here. Out there, I think a lot of students already doing A, and Reddit is filled with B, soon to be bots asking bots

      2 votes