Why are electric kettles so noisy?

Answer

Chris Smith - Ah, yes my kettle is no exception and the reason that kettles are noisy, they make that sort of thumping and bashing noise as they boil and then the noise intensifies as they warm up and then it goes silent as they boil. It is because of the way that the heat is being transferred into the water. So you have an electric element inside the kettle, a high current is passing through that element which makes it get hot. The heat from the element is therefore transferred by convection and conduction locally onto the water molecules around the element; they then get excited and get hot. So you have a bubble of hot water around the element which tries to expand and it also floats upwards away from the element because, of course, warm things rise but as it rises of course it loses its heat again to all of the surrounding water. So this bubble of water and water vapour collapses in on itself very quickly and that's cavitation and you get a shocking, sort of knocking noise. So those thumps that you hear and the sort of 'shhh' hissing that you hear, as the water vapour bubbles collapsing on themselves and emitting some sound waves, that's what the sound is.

Dave - Sounds of the bubbles, as the water is boiling, forming little bubbles of steam and as they rise up in the colder water they shrink and collapse and then smash into one another and make lots of noise. So it gets a lot quieter once bubbles get all the way up to the surface and they stop cavitating.

Helen Scales - It makes more noise I think when I have less water because I try and have as little as I need for a cup of tea, obviously covering the element but not lots more to save on energy and I think that's noisier.

Chris Smith - It could be there's a bigger resonant cavity inside the kettle because the bubble makes a sort of note inside the cattle and if you got lots of free space then the air will help to move around and bounce and sound around inside the kettle like an echo chamber. So that might be why you are hearing more sounds, probably what's going on.

Comments

Noisy Electric Kettle

Permalink Submitted by Anonymous (not verified) on Fri, 21/12/2018 - 08:12

Maybe there is a minor leak into the tube containing the element. That water would get very hot very quickly and cause the noise - until it had dried out from the tube.

No!

Permalink Submitted by chris on Fri, 21/12/2018 - 17:03

The supplied answer is the correct one. If there element were leaky there would probably be an explosion! It would certainly fuse the electrics.

Old type electric jug

Permalink Submitted by Richard (not verified) on Wed, 12/09/2018 - 08:54

I use a 50's 60's style electric jug and it hardly makes any noise at all. Just have to watch it as has no auto cut off on the one I have, It also boils that quick

Why when boiling on gas not so noisy?

Permalink Submitted by Emmanuil (not verified) on Sun, 18/02/2018 - 23:50

Then, why doesn't it make noise so loud when I boil with gas? Is it because water is heated more rapidly?

Because the heat is distributed over a larger area

Permalink Submitted by chris on Tue, 20/02/2018 - 22:40

I suspect that heating on a gas hob is quieter because the heat from the gas ring is applied over a larger area on the base of the kettle and also spreads out as it is conducted through the metal to make contact with the water. As a result the energy flow into the water is less focal, so there is probably a lower likelihood of bubbles of water vapour nucleating in few places around the element; this is what produces the cavitation sounds heard on an electric kettle.