yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Sparks from Falling Water: Kelvin's Thunderstorm


3m read
·Nov 10, 2024

So the people from the Hunger Games came to me and they asked me if I wanted to do an experiment that would be related to power generation. And strangely, there is this one idea that I've been thinking about for years, and now finally I have the chance to do it. Come check it out!

Positions... Here we go... Set... Yeah... Dolly... Lights! and... Action! We have a setup here with two rain shower heads, making two strings of water. Now each stream is gonna pass through a set of coils - right up by where they're released - and then it passes through this wire mesh down below.

Now these two sets of coils... So this set of coils is separate from this set of coils. And they're each connected to one of these bowls here. Once we get the water flowing, we should be able to generate a little electric spark right here. There it is...!

What's incredible is that we're generating a spark, which is probably five to ten thousand volts. It would give you a decent little shock. I mean it's not actually dangerous, because, although the voltage is high, there is not that much charge behind it. So you can't get that much current flowing. And current is what does really does damage.

Now the question is: 'how, just out of this setup where we have falling water and some pieces of metal, do we generate ten thousand volts?!' Well the way it works is that ... normally water is perfectly neutral; there's even numbers of positive ions and negative ions. But, as the water comes down of these two shower heads, sometimes there's gonna be a slight imbalance; maybe a little more negative in this stream and a little more positive in that stream.

Now normally that just kind of washes out over time... But not in this case...! Here's the ingenious part... The mesh on the left is connected to the ring on the right... So, if this mesh becomes negatively charged, then so does this ring... And now that ring will attract the positively-charged water. So this whole stream becomes positively charged.

Therefore, when it lands on this mesh, this mesh becomes positively charged as well. Which means this coil over here is positively charged, forcing the negative ions to be coming out of this stream more. And so, what we have is a clear separation of charge. There's a positively-charged stream on the right, and a negatively-charged stream on the left.

If you look closely at the streams, what you can actually see is they get more and more attracted to these top coils. And then the spark goes... and they reset. So basically, what's happening is we're building up charge on these coils. And then, when the charge gets big enough, it jumps across from the negative side to the positive side, and everything becomes neutral again, and the charging process can start afresh.

It's a pretty phenomenal piece of physics. I mean, it's such a basic setup ... and yet it produces this very impressive result. This was noticed over a hundred of years ago by a guy named Lord Kelvin. So it's often called 'Kelvin's Water Dropper', or 'Lord Kelvin's Rainstorm'. It's a really impressive phenomenon.

But you might be wondering 'how much energy could I really get out of this system?' Well, to put this in perspective, if you were to charge your phone on the energy generated by this setup, it would take six and a half years to reach full charge... So this is a very tiny amount of energy generation that we're talking about.

You know, an interesting thing to consider is 'where does this electrical energy come from?' All we really have is just falling water and metal pipes... I want you to leave me your answer in the comments below, or make me a video response.

More Articles

View All
Rule of 70 to approximate population doubling time | AP Environmental Science | Khan Academy
When we’re dealing with population growth rates, an interesting question is how long would it take for a given rate for the population to double. So we’re going to think about doubling time now. If you were to actually calculate it precisely, mathematica…
Khan Academy view of mastery learning
The terms mastery learning are used a lot these days, but I want to do a video on them because they can mean different things to different people. I want to talk about what it means, at least in a Khan Academy context. So to give us some perspective, let…
How Investors Think About Ideas - Wufoo Cofounder Kevin Hale
Hi, my name’s Kevin Hale. I’m a partner here at Y Combinator. A lot of founders ask me, “How do I know if my idea is going to be interesting to an investor?” So today I’m going to talk about how investors think about ideas. Every startup idea usually is …
The Stock Market Just Flipped
What’s up, you guys? It’s Graham here. So hold on one second, I’m going to invest some money really quick. [Applause] Oops! Well, that’s basically what investing felt like this week after the inflation data came out. That’s right, in the last week we’ve …
Allopatric and sympatric speciation | Biology | Khan Academy
[Voiceover] In any discussion of biology or discussion of evolution, the idea of a species will come up over and over again. And we have a whole separate video on species. But the general idea, or the mainstream definition of a species, is a group of orga…
Homeroom with Sal and Regina Ross - Tuesday, March 8
Hi everyone, Sal Khan here from Khan Academy. Happy International Women’s Day! In honor of International Women’s Day, we have a special guest, someone who I know quite well, Khan Academy’s Chief People Officer, Regina Ross. We’re going to talk about her j…