Kettle noises

[edbenjohn]

What is the noise a kettle makes as soon as you turn it? It's obviously not the noise of the water boiling, coz it's not boiled!

[Isaacr]

It isn't the noise of water boiling but of the interaction of hot and cold water. When you turn a kettle on the element becomes hot very quickly, heating up the water immediately surrounding it. The water forms into bubbles that break off from the element and float into relatively cooler water, which causes them to collapse. It's this sudden implosion that you hear when you turn the kettle on at first, if you notice it dies down after a little while as the rest of the water in the kettle reaches a similar temperature and then gets noisier as the water nears boiling point.