Why does a kettle make noise?
Discussion
Making a cup of coffee there, I was listening to the kettle and got wondering. Obviously when it's boiling, and approaching boiling, the noise comes from steam being forced through the spout, as well as bubbles forming in the water.
However... even before the water is lukewarm, there's a hissing sound like white noise. This is quite loud, considering there are no moving parts in my electric kettle. What gives? Do I need a new kettle?
The element at the bottom reaches temperature very quickly, hence water in the vicinity of it will boil very quickly, forming small bubbles and making noise. If you keep the lid open at the start you should be able to see this. The kettle switches off once the entire volume of water reaches boiling point.
Or something...
Or something...
t, I almost did this earlier when pre-heating some water to cook rice.erdnase said:
Making a cup of coffee there, I was listening to the kettle and got wondering. Obviously when it's boiling, and approaching boiling, the noise comes from steam being forced through the spout, as well as bubbles forming in the water.
However... even before the water is lukewarm, there's a hissing sound like white noise. This is quite loud, considering there are no moving parts in my electric kettle. What gives? Do I need a new kettle?
More importantly, where do the bubbles come from?However... even before the water is lukewarm, there's a hissing sound like white noise. This is quite loud, considering there are no moving parts in my electric kettle. What gives? Do I need a new kettle?
Shaw Tarse said:
Ayahuasca said:
Most modern electric kettles are fitted with an alarm that emits a sound in the presence of urine - this could be what you are hearing.
I know many Daily Mail links make PHers piss boil, but who would wee in a kettle? 
NoNeed said:
erdnase said:
Making a cup of coffee there, I was listening to the kettle and got wondering. Obviously when it's boiling, and approaching boiling, the noise comes from steam being forced through the spout, as well as bubbles forming in the water.
However... even before the water is lukewarm, there's a hissing sound like white noise. This is quite loud, considering there are no moving parts in my electric kettle. What gives? Do I need a new kettle?
More importantly, where do the bubbles come from?However... even before the water is lukewarm, there's a hissing sound like white noise. This is quite loud, considering there are no moving parts in my electric kettle. What gives? Do I need a new kettle?
damn - too late.
Edited by Ayahuasca on Wednesday 29th September 20:18
Absolute rubbish, no electrolysis happens at all. The bubbles are steam (water vapour). Incidentally, the "steam" you see coming out of the spout is condensed vapour, steam itself is relatively invisible. I can see from your faces that this is news to you all!
The noise is caused because small bubbles of vapour are generated next to the hotplate/element. They then detach and attempt to rise. But, because the rest of the water is <100C the steam condenses and the bubble rapidly implodes, taking a tiny fraction of the gaseous volume. This sends a negative shock wave through the water, and it eventually hits the wall of the kettle causing a n audible 'pop'. Older lower power (and quieter) kettles generated more convection currents which moved the heating water out of the way before vapour could be generated.
As the water heats up, more and more vapour bubbles make it to the surface and escape. This is much more gradual and doesn't generate and sharp shock waves. Hence, a boiling kettle is quieter than a 'hissing' one that is just heating up.
ETA: Why do I know this crap....
The noise is caused because small bubbles of vapour are generated next to the hotplate/element. They then detach and attempt to rise. But, because the rest of the water is <100C the steam condenses and the bubble rapidly implodes, taking a tiny fraction of the gaseous volume. This sends a negative shock wave through the water, and it eventually hits the wall of the kettle causing a n audible 'pop'. Older lower power (and quieter) kettles generated more convection currents which moved the heating water out of the way before vapour could be generated.
As the water heats up, more and more vapour bubbles make it to the surface and escape. This is much more gradual and doesn't generate and sharp shock waves. Hence, a boiling kettle is quieter than a 'hissing' one that is just heating up.
ETA: Why do I know this crap....
Edited by Zad on Wednesday 29th September 20:33
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