Hi Today we're going to take a look at what I think is one of the most misunderstood and misused terms in all of engineering. We're going to look at the difference between voltage, power, and energy because people mix these up all the time. Heck, I'm even guilty of it. Occasionally say an energy when I actually mean power or vice versa.

And if you're not careful and you don't know exactly what you're talking about, you can sound like an absolute twit. And this is actually really important. but just in engineering, but in broader when talking about technology because we both like a good lot of the world these days. It runs on electrical energy, and we're always talking about solar.

and we're talking about energy production. energy consumption. It's pretty much what makes the modern world go around. So it's important to understand the differences between these three words here.

Let's get to it. So you should be familiar with voltage. It's simply the electrical potential difference. the potential difference between two different points.

And you can have different sources of voltage. You can have a battery, for example, you can have a solar cell or some other Junction type device like a thermocouple or a Peltier effect device. We can have a generator where you've got a wire through a moving magnetic field. for example, all sources of voltage.

Now, voltage isn't that easy. It can actually also be expressed and often is, and probably more correctly. So as the difference in electrical potential energy between two points we've introduced the word energy. Does that mean voltage is the same of energy? No, it's not.

That's the whole point of this video. So let's dig a bit deeper. Now, if you talk to a physicist, they'll tell you that voltage is energy per unit charge, and their correct energy is in joules and charges in coulombs. So you might have seen voltage equals J on C.

It's a basic engineering, electrical engineering and physics formula, but that doesn't mean that voltage is energy because you can have voltage with practically no energy. How can you do that? Well, you might be familiar with our static electricity. For example, you rub your feet on the carpet and you generate a big charge and that can generate tens of thousands of volts and you can discharge it. But you're not going to kill yourself over yourself because there's practically no energy in that voltage.

You can also say that the energy here is actually the potential energy, not the energy that we're going to talk about over here different things. So you can go into the physics of this until the cows come home and all that you know. Physics experts will jump into the comments and no doubt you know, try and explain things better. but you don't need to know that.

Just suffice it to say that voltage is not energy and you can actually have voltage in the absence of energy. Essentially, Hmm, make sense. Let's move on to power. Now, the unit of power is what's as you most likely know, and the power is equal to the voltage times the current P equals V times I Basic Ohm's law stuff.

Now what you should understand in this context of power is power is instantaneous. Power is the amount of power dissipated at that one instant in time. Or is it? Hmm. Here's where we kind of dig a bit deeper like we did on voltage.

So having just said that, power in watts is instantaneous. I Now have to tell you that what is actually defined as joules per second or the rate of energy produced per second, or the rate of energy dissipated per second for example. So there is a time component to that that per second the joules per second component. But as you'll see, it's still not the same as energy.

Power is very different from energy. So we want to get at once. And trust me, once we get through the detail here, I'll then explain the overall concept difference between power and energy. We're getting there.

But suffice it to say that in engineering in electrical engineering, in a power terms, either circuit theory or power generation or something like that, power is instantaneous even though it is there rate of energy per second. So you've got to have a current flowing to produce power. That's why if you've got no current flowing, then you have no power, even though you might have a high voltage. But in terms of electrical energy, circuit theory, energy, production, all that sort of thing.

When you're talking about power, you're talking about the power that's dissipated in the circuit once current starts flowing. because P equals V times I If current doesn't flow. If you have a circuit like this with a battery and a resistor, your switches open, no current flows, You still got your voltage of voltage. Here is still being generated.

That potential energy is still there, but no current flowing. Therefore, no power is being dissipated in this load, or no power is being consumed from the battery. So although technically what's actually power has that second component in it, it's only for electrical flow. In terms of actually talking about power, you can basically assume that it's instantaneous.

That's the best way to look at it. It is the power dissipated or consumed or generated at that particular moment in time. Now let's take a look at energy. Energy in the electrical engineering world is the usage of power.

What over time. So it's derived units: kilowatt, hours, what hours could be, what seconds, whatever combination you want. So the energy equals power times time. And it goes back to how I said.

You can think of power as being instantaneous, whereas energy is power over time. That's the main difference and it's a huge, fundamental difference. Now, here's the big takeaway from this: You can generate power, but you can't generate energy and vice versa. You can't store power, but you can store energy.

So it's incorrect to say that this battery stores power. You can't store power. It can generate power by creating a circuit and having the current flow. But it's it's stores energy, not power.

And that's a huge mistake a lot of people make. And you're like often you'll just slip up. Even if you know the difference, you might see energy instead of power or vice versa sometimes. But you know, if you're trying to be serious and explain things to people, you need to get the terminology right.

Power is not. Energy is very different. Let's take the example of a familiar home solar power system. You might have, say, a three kilowatt power system.

It can generate three kilowatts of power in the ideal Sun for example. That's what it's rated at, That's its power rate. In In what three kilowatts, three thousand watts. But you can't Then go and say, well, my house consumed ten thousand watts of power today that that's ridiculous.

It's meaningless because you've introduced a the time element of a in this case, a day 24 hours. It's how much power that you take or use from your solar power system over a day or an hour. because you're charged on your electricity bill. You're charged for energy.

You're not charged for power. You're charged in kilowatt hours. You might pay 10 or 20 cents per kilowatt hour over time. And that is the big difference.

You're not paying For power, you're paying for how much power you consume per unit of time. So you don't want to go and say, well, my home has a three kilowatt hour solar system. You sound like an idiot. Now let's take the D cell alkaline battery again as a real good example incentive difference between voltage, power and energy.

Here, a d-cell alkaline battery generates a nominal electrical potential difference of 1.5 volts that will obviously drop when it discharges. But let's say 1.5 volts. And what power can this generate? Well, what power can this deliver to a load? Well, that actually depends on the internal resistance, the battery. You've got to get into the electrochemistry and all that sort of jazz and you know I'm not going to give you an answer.

but suffice it to say there will be a maximum power point Google that one where there will be depending upon the load resistance and the internal resistance of the battery that when the load is equal to the ESR that will be the maximum amount of power that this thing can deliver the instantaneous power. Now, the energy. The amount of energy stored in this battery. There is no power stored in this battery.

You remember, you can't store power, but you can store energy so there's energy in here and it has a nominal rating of approximately 25 watt hours for a typical D cell alkaline battery like this. Now you might see the more familiar you know milliamp-hour figure of say, 18000 for an alkaline D cell. That's actually strictly incorrect because energy is what's per hour per time power in what? So if you're talking in terms of milliamps, you're not actually correct and that's why I say take your mobile phone battery for example, it might have the what hour figure printed on There might say it's 5 watt hours and that is the correct energy capacity because it's taking into account the drop in voltage because the voltage is not constant and then suddenly dies it tapers off so it's more correct. In fact, it's 100% correct to say to give a what hour energy storage figure in a battery.

So with a 25 watt hour capacity battery, it could potentially deliver 25 watts for an hour or one watt for 25 hours. Simple. So I hope you found that interesting and useful. the difference between voltage, power, and energy.

The most common misconception, of course, is the difference between power and energy. One is instantaneous. One is a measurement over time. And just keep in mind these facts about our storage and non storage and generation and non generation.

But you know some people won't make the ridiculous claim that this has 1.5 volts of energy or 1.5 volts of power. It's like all, no, and that's what actually prompted this video. I Actually saw a video of a student actually say, well, how much energy can a particular system that he was measuring actually produced And the answer was point two volts like No So so what we'll do now is just quickly go to the bench and I'll show you an example of energy measurement. Now let me give you a quick a practical example of the difference between power and energy.

I've got my Gossin Metra head energy multimeter. Here it can measure power and energy. I've got just a 5 volt power supply hooked up to my dummy load here. So I've got five volts indoor constant current one amp load.

So voltage times current five volts times one amp is of course, five watts. That's our power. That's our instantaneous power at this moment in time. If I switch to say four volts R for example, then we'd get four watts.

So there is no time component to this. We're just reading out that instantaneous five watt value. Now, if I switch into energy mode by pushing the function button and I reset the timer, you will notice that we now have a timer in there counting from zero and you'll notice that the units have changed from what to milli watt hours. All watt hours basically.

so you can see it accumulating over time, but based on how much time we're running and this is exactly how the energy in your home is meted. For example, in kilowatt hours. So we've got an accumulation of power over time, it gives us energy and of course, the rate of this accumulation is going to depend on the instantaneous value value of the power at that point in time. So if we switch down to say back down to three volts instead of five, it's still building up.

but it's building up slower. If we go down to two volts, it'll go slower again. And of course, if we switch back, our timer's still accumulating in the background. But our instantaneous power in what is five watts.

but our energy is slowly building up over time. There you go. Most practical example: you can also do the example of battery capacity using the BK Precision 8601 electronic load here, which has a battery capacity discharge function. Now if we select the type of low, which is constant current.

Okay, if we set that to one end, then we can actually trigger. Now up, go into our battery mode. Here it let's say I've stopped voltage. Whatever.

Okay, we set our time and then we start it. You see that once we start accumulating over time, we've got five volts. It's drawn one amp from the battery site. So we've got a five volt battery and it's drawing one ampere.

You can see that the units are Amp hours. It's not what hours. It's amp hours. Because we're actually measuring a constant current load.

You can see that it accumulates. that amp hour capacity figure accumulates over time. But note that this is not an energy capacity. It's purely a amp hour capacity because it's not taking into account the voltage at all.

If you want that, if you want an energy capacity of a battery, you have to choose constant wattage. Now, if you're still having a little bit of trouble understanding this, let's try the standard water analogy for electrical circuits: The height of this dam. Here, We have a very nice-looking dam. It's Ker Dam, by the way.

In case you want to know the height of the dam like this, this is equivalent to the voltage due to the pressure given by the height of the dam. Now, the water flowing out here like this. the rate of flow of the water is the power. And if you actually narrow that gate there and control the amount of water flowing out, that's actually for the current.

But let's not go there, shall we? And you guessed it, the volume of water in the dam here is the energy. Get it. So this is why you can close off the gate to the dam here and have no water flowing. No power.

No current at all. But you have got the energy in the dam and you obviously can't store a rate of flow of water. You can't store power, but you can store energy. You can fill this dam up.

You can dam is like a rechargeable battery. You can fill it up and store energy in there, but you can't store the power like this. Get it? I Hope that's clear. So I hope you found that useful you need.

Please give it a big thumbs up and as always, discuss it down below. Catch you next. You.