A regular kettle might make a little noise, (I’m actually not sure) but the electric kettle gets so loud before the water boils that I can’t hear the news. What’s making the noise?
In: Engineering
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Its the cavitation – water heated right next to the heating element boils and turns into steam bubbles, the bubbles rise away from the heating element, lose their heat and turn back into water, causing the bubbles to collapse.
These bubbles collapsing makes the noise – it also gets deeper the closer it is to boiling, because the bubbles are able to get bigger before they collapse!
An electric kettle has quite a quiet small heat source with high power, it will heat up the water just beside it a lot faster than most of the water in it.
When you heat water hot enough it can produce a vapour above the air and water pressure and the bubble will expand and can detach and flow to the surface. When the bubble gets in contact with cooler water above it cools down and the pressure drops, when it is below the air and water pressure the bubble get compressed back to a liquid. It is the shockwaves of water slamming together that cause the sound. This is called [https://en.wikipedia.org/wiki/Cavitation](https://en.wikipedia.org/wiki/Cavitation)
In a kettle on a stow, the heating is slower and more spread out so water has a chance to mix. The temperature is more uniform and you get less bubbles that collapse so less sound is produced.
[https://www.youtube.com/watch?v=CLtG85oS6Yk](https://www.youtube.com/watch?v=CLtG85oS6Yk)
When you turn on an electric kettle, the heating element inside starts to warm up. This heat transfers to the water, causing it to form tiny bubbles of steam at the bottom. These bubbles rapidly rise and collapse as they hit cooler water, making a lot of noise. Once the water gets hot enough, the bubbles rise smoothly to the top, and the noise decreases. So, the noise is mostly from those bubbles forming and collapsing before the water boils.
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